- Email: [email protected]
Effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joint between pure aluminium and AISI 304 stainless steel
Journal of Manufacturing Processes 25 (2017) 116–125
Contents lists available at ScienceDirect
Journal of Manufacturing Processes journal homepage: www.elsevier.com/locate/manpro
Effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joint between pure aluminium and AISI 304 stainless steel M. Kimura a,∗ , K. Suzuki b,1 , M. Kusaka a , K. Kaizu a a b
Department of Mechanical Engineering, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan
a r t i c l e
i n f o
Article history: Received 26 September 2016 Received in revised form 22 November 2016 Accepted 3 December 2016 Keywords: Friction welding Aluminium Austenitic stainless steel Friction welding condition Joint efficiency Bend ductility
a b s t r a c t Aluminium (Al) and stainless steel have such some advantages as high functionalities for the industrial usage. However, the dissimilar joints have severe problems such as generating the intermediate layer consisting of a brittle intermetallic compound (IMC interlayer) during welding process. Friction welding is very useful for making of dissimilar joint. This paper described the effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joints between pure Al (CPAl) and austenitic stainless steel (AISI 304). The joining phenomena during the friction process such as joining behaviour, friction torque, temperature changes at the weld interface, and transitional changes of the weld interface were investigated. The effects of friction time and forge pressure on the tensile strength and bend ductility of joints were also investigated, and the metallurgical characteristics of those were observed. The joint, which had high joint efficiency, the fracture on the CP-Al side with no crack at the weld interface, and no IMC interlayer on the weld interface, could be successfully achieved. Then, the joint should be made with a high forge pressure of 150 MPa, the opportune friction time at which the temperature on the weld interface reached about 573 K or higher, and those friction welding conditions were suggested for obtaining good joints with high joint efficiency and the bend ductility of 90◦ . © 2016 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.
1. Introduction Aluminium (Al) and its alloys (referred to as Al-system material) are well-known materials that have highly attractive characteristics in terms of metallurgical and mechanical properties, e.g., high electrical and thermal conductivity, excellent corrosion resistance, light weight, and high specific strength. They are widely used for important structural components in automobiles, aerospace, and so on. On the other hand, fusion welding between Al-system material and such other materials as steel [1–3], copper (Cu) [1,4], and titanium (Ti) [5] has poor mechanical properties because of the brittle intermetallic compound (IMC) interlayer produced at the joint interface [6]. In addition, fusion welds between Al or its alloys and various steels have severe problems, e.g. generating of blowhole and crack at the joint interface [1–3]. However, a joining between Al-system materials and other materials has some superior inter-
∗ Corresponding author. E-mail address: [email protected] (M. Kimura). 1 Present: Mitsubishi Electric Corporation, Himeji Works, Japan.
est items, because joints of a combination with dissimilar materials have such some advantage points as the low cost solutions for the engineering requirements in the industrial usage. Therefore, a welding process for the joint between Al-system material and other material, which will result in less degradation of the mechanical and metallurgical properties, is urgently required. The solid state joining methods such as diffusion welding, friction welding, and friction stir welding, can be applied to join between Al-system material and other materials. Many researchers have reported that the mechanical and metallurgical properties of the friction welded joints of Al-system materials and various carbon steels [7–13] or stainless steels [16–23] show desirable characteristics. For example, the friction welding condition for the joint that had the good tensile strength of the joint between Al-system materials and various carbon steels was individually demonstrated as following combinations: various Al alloy and various steels by Elliott and Wallach [7], and Yilmaz et al. [8], pure Al and mild steel by Kumar et al. [9], AA5052 Al alloy and mild steel by Lee et al. [10] and Yamamoto et al. [11], and AA6061 Al alloy and mild carbon steel by Ochi et al. [12] and Taban et al. [13]. Additionally, the joint strength of friction stir spot welded joint between AA6061
http://dx.doi.org/10.1016/j.jmapro.2016.12.001 1526-6125/© 2016 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
117
Table 1 Chemical compositions and mechanical properties of materials used. (a) CP-Al Chemical compositions, wt.% Fe Si
Cu
Mg
V
Ti
Al
Mechanical properties UTS, MPa 0.2% YS, MPa
El., %
0.03
0.011
0.02
0.01
0.01
bal.
120
27
0.1
118
(b) 304SS Chemical compositions, wt.% C Mn Si
P
S
Ni
Cr
Fe
Mechanical properties UTS, MPa 0.2% YS, MPa
El., %
0.05 0.07
0.03 0.03
0.02 0.03
8.1 8.18
18.22 18.48
bal. bal.
680 670
47 57
1.54 1.5
0.46 0.49
Al alloy and mild steel by Sun et al. [14] as well as that of friction stir welded joint between AA5052 Al alloy and high strength low alloy steel by Ramachandran et al. [15] were also investigated. In those ways, some researchers have reported that the joining of Alsystem materials and various carbon steels could be successfully achieved and a relatively good joint was obtained. Furthermore, the characteristics of joints between Al-system materials and various stainless steels were investigated. For example, Sahin [16] and Sunay et al. [17] studied the joint strength and the characteristics of the IMC interlayer of the joint between pure Al and American Iron and Steel Institute (AISI) standard type 304 austenitic stainless steel. Shubhavardhan and Surendran [18] investigated the properties of the IMC interlayer of the joint for this combination, and Alves et al. [19] reported the measuring method of the weld interface of the joint for this combination. Fukumoto et al. [20] described the details microstructure at the adjacent region of the weld interface of the joint for this combination. Reddy et al. [21] and Ashfaq et al. [22] explained the joint strength and the characteristics of the IMC interlayer of the joint between AA6061 Al alloy and 304 stainless steel. Paventhan et al. [23] tried the optimization for the friction welding condition of the joint between AA6082 Al alloy and 304 stainless steel. Nevertheless, the joining mechanism of friction welding between Al-system materials and various stainless steels has not been fully clarified, so that the friction welding conditions for material combinations are determined by trial and error. That is, the joining mechanism of friction welding for dissimilar materials was not clarified, and the theoretical friction welding condition that the joint does not fracture from the weld interface was not presented. Moreover, the joining mechanism of friction welding for dissimilar materials differs from that of similar materials, since the mechanical properties such as the tensile strength and the thermal properties such as the thermal conductivity are different from the combinations of similar materials. Naturally, it is considered that the friction welding condition of the joint without the fracture from the weld interface will be differed with between the combination of Al-system materials on carbon steels and the combination of Alsystem materials on stainless steels. To determine the theoretical friction welding conditions, it is very essential to clarify the joining phenomena and the joint mechanical properties. In particular, the clarifications of the joining mechanism are strongly required concerning the weldability between the Al-system materials and various stainless steel, because an expansion in the use of the joint with those combination is expected and widely used in various component parts such as spacecraft parts. In previous works [24–26], the authors clarified the joining mechanism during the friction welding process of similar material combinations that were various carbon steels [24] or Al-system materials [25,26]. Furthermore, the authors also clarified the joining mechanism of some dissimilar material joints as following combinations: pure Al and pure Cu [27], Al-system materials and low carbon steel (LCS) [28,29], Cu-system materials and low carbon steel [30,31], pure Cu and pure Ti [32], and pure Ti and LCS [33]. If combinations of dissimilar materials between Al-system materials
475 435
and stainless steels can be joined using the same welding method as that shown in previous reports [24–33], the joining mechanism will be clarified. Then, it will be possible to clarify the difference of the friction welding condition of the joint between Al-system materials and LCS [28,29]. Therefore, to weld Al-system materials and stainless steels by the experiment is necessary for clarification of the joining mechanism. Based on the above background, the authors have been carrying out research to clarify the joining mechanism during the friction process of the dissimilar joint. The authors investigate the joining phenomena during the friction process of friction welds between pure Al and AISI 304 stainless steel of a typical austenitic stainless steel in the present work. The authors show the tensile strength and bend ductility of the friction welded joints under various friction welding conditions, especially the effects of friction time and forge pressure on those. Moreover, the authors show the theoretical friction welding condition for joints that had the bend ductility of 90◦ with no crack at the weld interface by bending test as well as the fracture on the CP-Al side by tensile test. 2. Experimental procedure 2.1. Materials and specimen shapes The materials used were commercially pure Al (type JIS A1070BD-F, referred to as CP-Al) and AISI 304 austenitic stainless steel (JIS SUS304, referred to as 304SS) in 16 mm diameter rods. The chemical compositions and the ultimate tensile strength (UTS), the 0.2% yield strength (YS), and the elongation (El.) for materials used were shown in Table 1. In this case, two kinds of 304SS having slightly different tensile properties were used for this experiment since they were purchased at different times. Both rods were used for this experiment as received condition. Those rods were machined to 12 mm in a diameter of the weld faying (contacting) surface. The temperature changes at the centreline, half radius, and periphery locations of 1.0 mm longitudinal direction from the weld faying surface were measured using the 304SS specimen for clarification of the temperature during the friction process, of which was shown in Fig. 1. In this connection, although the temperature
Fig. 1. Shape and dimensions of friction welding specimen of 304SS for measuring temperature change at weld interface.
118
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
Fig. 2. Schematic diagrams of bending test methods.
on the weld interface will be able to estimate as those measuring positions or higher, the sufficient data to the clarification of the joining phenomena could be obtained in order to understand the temperature distribution of the radius direction on the weld interface. The details of the specimen shape for measuring temperature changes have been described in a previous report [28]. All weld faying surfaces of the specimens were polished by a surface grinding machine before joining to eliminate the effect of surface roughness on the joint mechanical properties [32]. 2.2. Friction welding method A continuous (direct) drive friction welding machine was used for the joining. During the friction welding operations, the friction welding condition was set to the following combinations: a friction speed of 27.5 s−1 (1650 rpm), a friction pressure of 30 MPa, a range of friction times from 0.04 to 3.0 s, a range of forge pressures from 30 to 150 MPa, and a forge time of 6.0 s. To observe the joining phenomena during the friction process and to obtain the joint without the braking deformation, the authors carried out three experimental methods as follows. (1) A conventional friction welding method that have a brake system when the friction time expired. (2) The welding method that the fixed side specimen is simultaneously and forcibly separated from the rotating side specimen when the friction time expired. This welding method was performed for observation of the transitional changes of the weld interface. (3) The welding method that the relative speed on the weld interface between both specimens is simultaneously decreased to zero when the friction time expired. This welding method was used to prevent braking deformation during rotation stop. Then, this welding method was performed for measurement of the mechanical and metallurgical properties of joints. In this connection, the friction torque was measured with a load-cell, and the temperatures were measured with mineral insulated thermocouples composed with a chromel–alumel, those were inserted to holes of the 304SS specimen. Then, the friction torque and temperature were recorded with a personal computer through an A/D converter with a sampling time of 0.001 s. Furthermore, when joints were made by the experimental method of (1), i.e. the conventional friction welding method, the rotation of the specimen is not instantly stopping. That is, it was necessary of the braking time for rotation stop, because the rotation of the specimen is not stopped completely at setting friction time. Hence, the experimental method of (3) was carried out for making of the joint with setting friction time, and those joints were used for measurement
of the mechanical and metallurgical properties. The details of these methods have been also previously described [28]. 2.3. Tensile and bending test methods All joint tensile test specimens were machined to 12 mm in the diameter and 66 mm in the parallel length. That is, all flash (burr or collar), which was exhausted from the weld interface during the friction welding process, were removed from joints for joint tensile test specimens. Moreover, the joint bending test was carried out for clarification of the bend ductility of joint. The flash and the chucking part of both sides were removed and machined to a 12 mm diameter for a bending test. By the way, three-point or four-point bending could not be applied satisfactorily, because of the significant difference in strength between the CP-Al and 304SS base metals. Consequently, the 304SS side was held stationary in a vice and the CP-Al side was bent to a maximum angle of 90◦ as shown in Fig. 2a (referred to as a single direction bending test). Furthermore, the joint with the bend ductility of 90◦ was bent to the opposite direction to 90◦ as almost straight bar shape, and then this joint was bent to a maximum angle of 90◦ . That is, the joint with the bend ductility of 90◦ was also bent to the opposite direction with a maximum angle of 180◦ as shown in Fig. 2b (referred to as a reverse direction bending test). Then, the incidence of crack at the joint interface was observed in each case. The joint tensile and bending tests were performed with as-welded condition at room temperature. 2.4. Hardness test and SEM observation methods Vickers hardness test at low test force, i.e., the Vickers microhardness (referred to as Vickers hardness), was carried out at room temperature for clarification of the joint properties. Measuring load was 2.94 N (0.3 kgf), and the measuring range was about 10 mm from the weld interface to both sides. SEM observation via EDS analysis was performed to analyze the chemical composition on the adjacent region of the weld interface. The fractured surface of the joint after joint tensile testing was analyzed using X-ray diffraction analysis and SEM observation via EDS analysis. 3. Results 3.1. Observation of joining phenomena during friction process 3.1.1. Relationship between joining behaviour and friction torque Fig. 3 shows the relationship between the joining behaviour and the friction torque. Photos 1)–6) in Fig. 3a correspond to the friction torque of (1)–(6) in Fig. 3b, respectively. Photo 1) shows the state at the weld faying surfaces as they contacted each other,
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
119
Fig. 3. Joining behaviour and friction torque curve during friction process.
then the friction torque was increased. The CP-Al side was slightly upset (deformed) as shown in Photo 2), and then the friction torque reached the initial peak of (3) in Fig. 3b. In this instance, the initial peak torque was approximately 15 Nm, and the elapsed time for the initial peak was about 0.5 s. The numerical value of the initial peak torque was almost similar to that of the joint between CP-Al and LCS (referred to as CP-Al/LCS joint) at the same friction pressure [28] and this elapsed time for the initial peak was shorter than that of its joint. Thereafter, the upsetting and the flash of CP-Al increased with friction time though the 304SS side was not upset, as shown in photos (4) and (5) in Fig. 3a. 3.1.2. Temperature change during friction process Fig. 4 shows the temperature changes with the friction torque during the friction process. All measured temperatures increased with friction time. Although all measured temperatures were almost the same before the friction torque reached the initial peak, the temperature after this friction time was high in the order of the periphery, half radius, and centreline locations. However, the difference in each temperature was about 50 K or less at a friction time of about 1.0 s or longer, and the temperature of the half radius location at this friction time was about 573 K (300 ◦ C). Then, when a
Fig. 4. Relationship between friction time and temperature changes at various measured locations of 304SS side during friction process, in relation to friction torque curve.
Fig. 5. Appearances of weld interfaces after welding at various friction times.
120
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
Fig. 6. Relationship between friction time and joint efficiency of joints, in relation to friction torque; forge pressure of 30 MPa.
friction time was 2.0 s, those temperatures reached to about 723 K (450 ◦ C). Thereafter, the temperature of the periphery location was a little higher than that of others, and then those reached to about 750 K (477 ◦ C) at a friction time of 3.0 s. 3.1.3. Transitional changes of weld interface Fig. 5 shows the examples of the appearances of the weld interfaces after welding at various friction times. When a friction time was 0.04 s, i.e. both specimens had been rotated once, the concentric rubbing marks were observed at the half radius portion of the weld interface of both sides. CP-Al transferred to the weld interface on the 304SS side. When a friction time was 0.2 s, the concentric rubbing marks on the CP-Al side were extended to the central and peripheral portions, and the transferred CP-Al on the 304SS side increased. Then, almost whole weld interface on the 304SS side had the transferred CP-Al at a friction time of 0.5 s, i.e. the friction torque close to the initial peak, and the flash on the CP-Al side was increased. The transferred CP-Al on the peripheral portion of the weld interface was less than that of other portions. Thereafter, the weld interface on the 304SS side was almost similar although the flash on the CP-Al side was increased with friction time. Also, the 304SS flash was hardly observed at all friction times. Based on these results, it was clarified that the entire weld interface of the 304SS side had the transferred CP-Al when the friction torque reached the initial peak. 3.2. Investigation of mechanical and metallurgical characteristics 3.2.1. Relationship between tensile strength of joint and friction time Fig. 6 shows the relationship between the friction time and the joint efficiency of joints, and those were plotted alongside the friction torque curve. The joint efficiency was defined as the ratio of joint tensile strength to the ultimate tensile strength of the CPAl base metal. Fig. 7 shows examples of the appearances of the joint tensile tested specimens. In this instance, forge pressure was applied at an identical friction pressure, i.e. 30 MPa. The joint efficiency at a friction time of 0.2 s was approximately 15%. The joint fractured at the weld interface as shown in Fig. 7a, although it had a little CP-Al adhering on the weld interface of the 304SS side. Incidentally, the CP-Al and 304SS were not joined before a friction time of 0.2 s because a sufficient quantity of friction heat for welding could not be produced. The joint efficiency increased with increasing friction time, and then it was approximately 63% efficiency at a friction time of 0.5 s, i.e. the friction torque close to the initial peak.
Fig. 7. Examples of appearances of joint tensile tested specimens.
However, the joint efficiency had a scattering. Then, the joint efficiency maintained approximately 70% after this friction time. Some joints, which were made with a friction time of 2.0 s or longer, fractured between the weld interface and the CP-Al side (referred to as mixed mode fracture) as shown in Fig. 7b. Thereafter, when joints were made a friction time of 2.5 s or longer, some joints fractured from the CP-Al side as shown in Fig. 7c. The fracture was produced at the near part of the weld interface in the CP-Al side. However, all joints, which had the fracture in the CP-Al side with 100% joint efficiency, were not obtained at a forge pressure of 30 MPa. In contrast, CP-Al/LCS joint fractured on the CP-Al side after the friction time that the friction torque reaches the initial peak [28]. Therefore, it was clarified that the friction welding condition of the joint without the fracture on the weld interface differed between the joint in this study and CP-Al/LCS joint [29]. To clarify the joint characteristics, the joint was performed to SEM observation. Fig. 8 shows the SEM image and EDS analysis result at the peripheral portion of the adjacent region of the weld interface for the joint. In this instance, the joint was made with a friction time of 3.0 s, and the SEM–EDS analysis was performed at the peripheral portion of the weld interface since this portion reached to such a high temperature condition as about 750 K during the friction process as shown in Fig. 4. The distribution lines corresponding to Al, Si, Fe, Cr, and Ni by EDS analysis had no plateau part at the weld interface, i.e., this joint did not have the IMC interlayer, although the weld interface was slightly unclear. The joints with other friction times as well as the other portions of these joints did also not have the IMC interlayer, although the temperature of the radius direction in the weld interface or the reached temperature at the weld interface differed as shown in Fig. 4 (data not shown due to space limitations). In addition, it is considered that the IMC interlayer will be not generated for the joint with a short friction time, since the joint with a long friction time of 3.0 s did not have IMC interlayer. It was able to estimate that the IMC interlayer at the weld interface is not generated this friction time (3.0 s) with the temperature of about 723 K. This thought was also able to estimate from the result, which the IMC interlayer was observed in the friction stir welded joint between AA3003 Al alloy and 304SS with post-weld heat treated at a holding time of about 60 s or longer [34]. Hence, it was clarified that the cause of the joint with the mixed mode fracture was not due to the IMC interlayer at the weld interface, and it was based on the SEM observation level.
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
121
Fig. 8. SEM image and EDS analysis result at peripheral portion of adjacent region of weld interface for joint; friction time of 3.0 s and forge pressure of 30 MPa.
Fig. 9 shows the SEM photographs and analysis results of chemical compositions for the fractured surfaces on CP-Al and 304SS sides of joint tensile tested specimens, respectively. This joint was made with a friction time of 1.5 s and a forge pressure of 30 MPa. Then, the peripheral portion of the fractured surface was observed. Only Al was detected on the fractured surface of the CP-Al side, and that was shown in Fig. 9a. On the other hand, Fe, Cr and Ni of which were corresponded to 304SS, and Al was detected on the fractured surface of the 304SS side (see Fig. 9b). Additionally, other portions on the fractured surfaces of this joint as well as that with another friction times had similar chemical compositions. Thus, the IMC interlayer was not observed in the joint, and it was clarified that the CP-Al and 304SS sides were not completely joined under this forge pressure (30 MPa). 3.2.2. Relationship between tensile strength of joint and forge pressure To improve the joint efficiency, the effect of forge pressure on joint efficiency was investigated. Fig. 10 shows the relationship between the forge pressure and the joint efficiency of joints at various friction times. When joints were made with a friction time of 0.6 s as shown in Fig. 10a, the joint efficiency at a forge pressure of 30 MPa was approximately 70% although it had scattering, and those fractured at the weld interface as shown in Fig. 7a. The joint efficiency slightly increased to approximately 80% with increasing forge pressure. The fractured point of the joint changed from the mixed mode fracture to the CP-Al side fracture. Then, when joints were made with a forge pressure of 150 MPa, all joints fractured on the CP-Al side, of which was shown in Fig. 11. In addition, the fractured point of this joint occurred in the position of the CP-Al side with about 10 mm longitudinal distance from the weld interface, and the weld interface had no defect such as cracks (compare Fig. 7c and Fig. 11).
Fig. 9. SEM–EDS analysis results at peripheral portion of fractured surfaces of joint tensile tested specimens; friction time of 1.5 s, and forge pressure of 30 MPa.
That is, the fractured point of this joint differed in comparison with that of a forge pressure of 30 MPa, although joints also fractured from the CP-Al side. The similar results were also obtained when the joint was made with friction times of 1.0 and 1.5 s as shown in Fig. 10b and c, although the joint efficiency differed. Furthermore, all joints at those friction times with a forge pressure of 135 MPa or higher fractured from the CP-Al side as shown in Fig. 11. Fig. 12 shows the appearance of the cross-section for the tensile tested specimen, which fractured in the CP-Al side. In this instance, the joint was made with a friction time of 1.0 s and a forge pressure of 150 MPa. The weld interface of the joint after tensile testing had neither a not-joined region nor defects such as cracks, and the fracture was produced at the part of the longitudinal direction over about 10 mm distance from the weld interface in the CP-Al side. That is, CP-Al and 304SS were tightly joined. Therefore, it was clarified that the joint with the CP-Al side fracture was obtained with such a high forge pressure as 150 MPa.
122
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
Fig. 12. Appearance of cross-section for tensile tested specimen with CP-Al side fracture; friction time of 1.0 s and forge pressure of 150 MPa.
Fig. 13. Vickers hardness distributions across weld interface of joints; friction time of 1.0 s and forge pressure of 30 and 150 MPa.
Fig. 10. Relationship between forge pressure and joint efficiency of joints at various friction times.
Fig. 11. Appearance of joint tensile tested specimen with CP-Al side fracture.
Fig. 13 shows the Vickers hardness distributions across the weld interface on the periphery location of joints with a friction time of 1.0 s. The joint with a forge pressure of 30 MPa had a softened area that extended about 4.0 mm in the longitudinal direction of the CPAl side. However, the joint with a forge pressure of 150 MPa did not have a softened area. The joints with the CP-Al side fracture
at other friction times as well as the other measuring locations of this joint did also not have the softened area. Hence, it was clarified that the joint had the fracture on the CP-Al side without 100% joint efficiency although it did not have the softened area on the adjacent region of the weld interface. The cause of the joint with the CP-Al side, of which did not have 100% joint efficiency, will be described later. Incidentally, the hardness of the 304SS base metal differed since used 304SS had different mechanical properties as shown in Table 1. 3.2.3. Relationship between joint bend ductility and forge pressure Based on the above results, the joint that was made with a friction time of 0.6 s or longer and a forge pressure of 150 MPa had the fracture in the CP-Al side as shown in Fig. 11. To clarify the joint properties in details, the joints were bent to a maximum angle of 90 ◦ by a single direction bending test as shown in Fig. 2a. Fig. 14 shows examples of the appearances of joint bending tested specimens by a single direction bending test. In this case, the joints were made with friction times of 0.6, 1.0, and 1.5 s, and a forge pressure of 120 MPa or higher, since those joints had the CP-Al side fracture as shown in Fig. 10. When joints were made with forge pressures of 120 and 135 MPa, some of those had the bend ductility of 90◦ with no crack at the weld interface regardless of friction time, and that was shown in Fig. 14b. However, some joints had cracks at the
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
123
friction heat, although the joint had the fracture on the CP-Al side by tensile test. However, the joint at a friction time of 1.0 s had the bend ductility of 90◦ in reverse direction with no crack at the weld interface as shown in Fig. 15b. That is, the sound joint was successfully achieved. Additionally, it was clarified that this joint was satisfied with the superlative grade of the classification of quality for friction welded joints on dissimilar metallic materials in JIS Z 3175 [35]. On the other hand, when the joint was made at a friction time of 1.5 s, it also had cracks at the weld interface. Hence, a friction time should be set to 1.0 s, because the softened area on the adjacent region of the weld interface of the joint will be expanded due to long friction time.
4. Discussion
Fig. 14. Appearances of joint bending tested specimens by single direction bending test.
Fig. 15. Appearances of joint bending tested specimens by reverse direction bending test; forge pressure of 150 MPa.
weld interface as shown in Fig. 14a. Hence, the joint with those forge pressures was not a sound joint. On the other hand, all joints, which were made with a forge pressure of 150 MPa, had the bend ductility of 90◦ with no crack at the weld interface (Fig. 14b). That is, the joints that were made with this forge pressure (150 MPa) had the fracture in the CP-Al side and the bend ductility of 90◦ . Furthermore, the joint bending test specimens by a single direction bending testing were bent with 180◦ of a reverse side as shown in Fig. 2b, for clarification of the joint properties under the more rigorous bending condition. Fig. 15 shows examples of the appearances of joint bending tested specimens by a reverse direction bending test. In this case, those joints were made with a forge pressure of 150 MPa. When the joint was made at a friction time of 0.6 s, it had cracks at the weld interface (Fig. 15a). Therefore, it was considered that the joint with this friction time did not have enough
Based on the above consequences, the joint that was made with a friction time of 1.0 s and a forge pressure of 150 MPa, had the fracture in the CP-Al side and the bend ductility of 90◦ . In addition, the joint had scarcely a softened area of the CP-Al side (see Fig. 13). Nevertheless, the joint efficiency of 100% was not obtained. Incidentally, the joining phenomena during the friction process of CP-Al/LCS joint [28] resembled those of the combination of the joint in this study. In other words, only the CP-Al side upset but 304SS side in this study hardly upset, which was showed in Fig. 3a. Therefore, the joint that did not have 100% joint efficiency was considered the change of the mechanical properties of the CP-Al base metal, because the fractured point of the joint occurred at the CP-Al side with about 10 mm longitudinal distance from the weld interface (see Fig. 11). That is, the cause of the joint, which was not obtained the joint efficiency of 100%, is able to consider the Bauschinger effect of the CP-Al base metal [28], and the difference of the anisotropic properties for as-manufactured condition [26] of the CP-Al base metal. First, CP-Al/LCS joint had the result of the joint efficiency decreased with increasing forge pressure in a previous report [28]. When the compressive stress was higher than the yield stress of the CP-Al base metal, the tensile strength of the CP-Al base metal with a high compressive load was lower than the yield strength with no compressive load. Moreover, the decreasing of the tensile rate of the CP-Al base metal could estimate at other temperature [28], as well as the Bauschinger effect in Al-system materials was affected at various temperatures [36,37]. Hence, one of the causes for decreasing joint efficiency of CP-Al/304SS joint was due to the change of the properties for the CP-Al base metal like the Bauschinger effect. Second, it was considered the difference of the tensile strength for the CP-Al base metal at the longitudinal and radial directions, since the flash of the CP-Al of the joint was exhausted to the radial directions from the longitudinal directions at the adjacent region to the weld interface (Figs. 3 and 5), and the fractured point of the joint was not the softened area of the CP-Al side (Fig. 12). Fig. 16 shows the cross-sectional appearances of the adjacent region of the weld interface of joints at various forge pressures. Those joints were made with a friction time of 1.0 s. The CP-Al side was pressed towards the longitudinal direction with increasing forge pressure although the quantity of flash of CP-Al almost maintained in spite of that increasing. Then, the fibre structure of the CP-Al base metal with corresponding to the longitudinal direction flowed to the radius (outer surface) direction from the longitudinal direction. That is, that fibre structure of the CP-Al base metal changed towards the radius direction at the adjacent region of the weld interface on the CP-Al side. Actually, the tensile strength of the radial direction of the Al alloy and pure Cu rods were slightly lower than that of the longitudinal direction, and that was described in previous reports [26,32]. Hence, it was considered that the joint was not obtained the joint efficiency of 100%, and one of the causes was also the difference of the anisotropic
124
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
Fig. 16. Cross-sectional appearances of adjacent region of weld interface for joints at various forge pressures; friction time of 1.0 s.
properties with as-manufactured condition of the CP-Al base metal. Incidentally, similar results of both the change of the properties for the CP-Al base metal like the Bauschinger effect and the difference of the anisotropic properties were also obtained in pure Cu/pure Ti joint [32] as well as CP-Al/LCS joint [28]. The fact that the joint did not have 100% joint efficiency was due to the decrease in the tensile strength of the CP-Al base metal by the Bauschinger effect as well as the difference of the anisotropic properties, although further investigation is necessary to elucidate the detailed mechanical properties of joints. However, a high forge pressure such as 150 MPa is necessary for the joint since it had cracks at the weld interface when it was made with such a forge pressure of 90 MPa (see Figs. 10, 14 and 15). Therefore, to obtain good joint for higher joint efficiency and bend ductility, the joint should be made with a high forge pressure of 150 MPa, and with the opportune friction time that the temperature on the weld interface reached to about 573 K or higher. This friction welding condition differed with CP-Al/LCS joint [28]. Hence, it is necessary to note in the selection of the friction welding condition for making good joint between Al-system materials and various steels.
5. Conclusions This report described the effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joint between pure aluminium (CP-Al) and austenitic stainless steel (JIS SUS304, 304SS). The following conclusions are provided.
(1) When joints were made at a friction pressure of 30 MPa with a friction speed of 27.5 s−1 , the upsetting (deformation) occurred at the CP-Al base metal. CP-Al transferred to the half radius region of the weld interface on the 304SS side, and then it transferred towards the entire weld interface. The temperature on the weld interface increased with friction time, and it reached to 573 K or over at a friction time of 0.6 s or longer. (2) When joints were made at a friction time of 0.6 s, i.e. the friction torque close to the initial peak, it had the joint efficiency of approximately 70% and fractured at the weld interface. Some joints, that were made at a friction time of 2.0 s or longer, had the mixed mode fracture (between the CP-Al side and the 304SS side) and the CP-Al side fracture. However, the joint efficiency of 100% was not obtained because the CP-Al side at the adjacent region of the weld interface softened. (3) When joints were made with a forge pressure of 150 MPa, all joints fractured from the CP-Al side, although those had the joint efficiency of approximately 80%. Nevertheless, the joint had hardly a softened area at the adjacent region to the weld
interface of the CP-Al side. Those joints did also not have the intermetallic compound (IMC) interlayer on the weld interface. (4) The joints, which were made at a friction time of 1.0 s with a forge pressure of 150 MPa, had the bend ductility of 90◦ in a single direction with no crack at the weld interface. This joint had also the bend ductility of 90◦ in reverse direction with no crack. (5) The fact that the joint did not have 100% joint efficiency was due to the decrease in the tensile strength of the CP-Al base metal that was occurred by the Bauschinger effect as well as the difference of the anisotropic properties. In conclusion, to obtain good joint for higher joint efficiency and bend ductility, the joint should be made with such a high forge pressure as 150 MPa, and with the opportune friction time that the temperature on the weld interface reached to about 573 K or higher. Acknowledgements The authors wish to thank the staff members of the Machine and Workshop Engineering at the Graduate School of Engineering, University of Hyogo. Also, the authors wish to thank Emeritus Prof. Dr Akiyoshi Fuji and technical officer Mr Harumi Hashimoto in Kitami Institute of Technology for their kind and aggressive assisting to this study. References [1] Technical Committee on Structural Transition Joint. Studies on the properties of aluminium alloy-steel transition pieces for structural transition joint (STJ) of ship superstructure. J Light Met Weld Constr 1978;16(8):345–64 [in Japanese]. [2] Ueda Y, Niinomi M. On the alloy layers formed by the reaction. J Jpn Inst Met 1978;42(6):543–9 [in Japanese]. [3] Sasabe S, Matsumoto T, Iwase T, Hattori Y, Miono T. Study on the factors in creating the IMC free region—dissimilar metal joining of aluminum alloys to steel in MIG-braze welding by using the advanced hot-dip aluminized steel sheet. Q J Jpn Weld Soc 2010;28(1):54–60 [in Japanese]. [4] Dawson RJC. Welding of copper and copper-base alloys. Weld Res Counc Bull 1983;287:1–17. [5] The Japan Titanium Society. Titanium. Tokyo: Kogyo Chosakai Publishing; 2007. p. 268–9 [in Japanese]. [6] American Welding Society. Welding handbook, vol. 4, 7th ed. American Welding Society: Miami. FL; 1982. p. 537–8. [7] Elliott S, Wallach ER. Joining aluminium to steel part 2—friction welding. Met Constr 1981;13(4):221–5. [8] Yilmaz M, C¸öl M, Acet M. Interface properties of aluminum/steel frictionwelded components. Mater Charact 2003;49:421–9. [9] Kumar S, Kumar R, Singla YK. To study the mechanical behaviour of friction welding of aluminium alloy and mild steel. Int J Mech Eng Rob Res 2012;1(3):43–50. [10] Lee WB, Yeon YM, Kim DU, Jung SB. Effect of friction welding parameters on mechanical and metallurgical properties of aluminium alloy 5052-A36 steel joint. Mater Sci Technol 2003;19:773–8. [11] Yamamoto N, Takahashi M, Aritoshi M, Ikeuchi K. Effect of intermetallic compound layer on bond strength of friction-welded interface of Al-Mg 5052 alloy to mild steel. Q J Jpn Weld Soc 2005;23(2):352–8 [in Japanese].
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125 [12] Ochi H, Ogawa K, Yamamoto Y, Suga Y. Bending tensile torsional strength of friction welded joint of 6061 aluminum alloy and S45C carbon steel. J Jpn Soc Fract Strength Mater 1994;28(4):143–54 [in Japanese]. [13] Taban E, Gould JE, Lippold JC. Dissimilar friction welding of 6061-T6 aluminum and AISI 1018 steel: properties and microstructural characterization. Mater Des 2010;31:2305–11. [14] Sun YF, Fujii H, Takaki N, Okitsu Y. Microstructure and mechanical properties of dissimilar Al alloy/steel joints prepared by a flat spot friction stir welding technique. Mater Des 2013;47:350–7. [15] Ramachandran KK, Murugan N, Kumar SS. Friction stir welding of aluminum alloy AA5052 and HSLA steel. Weld J 2015;94(9):291s–300s. [16] Sahin M. Joining of stainless-steel and aluminium materials by friction welding. Int J Adv Manuf Technol 2009;41:487–97. [17] Sunay TY, Sahin M, Altintas S. The effects of casting and forging processes on joint properties in friction-welded AISI 1050 and AISI 304 steels. Int J Adv Manuf Technol 2009;44:68–79. [18] Shubhavardhan RN, Surendran S. Friction welding to join dissimilar metals. Int J Emerg Technol Adv Eng 2012;2(7):200–10. [19] Alves EP, Neto FP, An CY, da Silva EC. Experimental determination of temperature during rotary rriction welding of AA1050 aluminum with AISI 304 stainless steel. J Aerosp Technol Manag 2012;4(1):61–7. [20] Fukumoto S, Tsubakino H, Aritoshi M, Tomita T, Okita K. Dynamic recrystallisation phenomena of commercial purity aluminium during friction welding. Mater Sci Technol 2002;18(2):219–25. [21] Reddy GM, Rao AS, Mohandas T. Role of electroplated interlayer in continuous drive friction welding of AA6061 to AISI 304 dissimilar metals. Sci Technol Weld Joining 2008;13(7):619–28. [22] Ashfaq M, Sajja N, Rafi HK, Rao KP. Improving strength of stainless steel/aluminum alloy friction welds by modifying faying surface design. J Mater Eng Perform 2013;22(2):376–83. [23] Paventhan R, Lakshminarayanan PR, Balasubramanian V. Prediction and optimization of friction welding parameters for joining aluminium alloy and stainless steel. Trans Nonferrous Met Soc China 2011;21:1480–5. [24] Kimura M, Kusaka M, Seo K, Fuji A. Observation of joining phenomena in friction stage and improving friction welding method. JSME Int J Ser A 2003;46(3):384–90. [25] Kimura M, Kusaka M, Seo K, Fuji A. Joining phenomena during friction stage of A7075-T6 aluminium alloy friction weld. Sci Technol Weld Joining 2005;10(3):378–83.
125
[26] Kimura M, Choji M, Kusaka M, Seo K, Fuji A. Effect of friction welding conditions on mechanical properties of A5052 aluminium alloy friction welded joint. Sci Technol Weld Joining 2006;11(2):209–15. [27] Kimura M, Inui Y, Kusaka M, Kaizu K, Fuji A. Joining phenomena and tensile strength of friction welded joint between pure aluminum and pure copper. Mech Eng J 2015;2(1). No. 14-00328. [28] Kimura M, Ishii H, Kusaka M, Kaizu K, Fuji A. Joining phenomena and joint strength of friction welded joint between pure aluminium and low carbon steel. Sci Technol Weld Joining 2009;14(5):388–95. [29] Kimura M, Ishii H, Kusaka M, Kaizu K, Fuji A. Joining phenomena and joint strength of friction welded joint between aluminium-magnesium alloy (AA5052) and low carbon steel. Sci Technol Weld Joining 2009;14(7):655–61. [30] Kimura M, Kusaka M, Kaizu K, Fuji A. Effect of friction welding condition on joining phenomena and tensile strength of friction welded joint between pure copper and low carbon steel. J Solid Mech Mater Eng 2009;3(2):187–98. [31] Kimura M, Kasuya K, Kusaka M, Kaizu K, Fuji A. Effect of friction welding condition on joining phenomena and joint strength of friction welded joint between brass and low carbon steel. Sci Technol Weld Joining 2009;14(5):404–12. [32] Kimura M, Saitoh Y, Kusaka M, Kaizu K, Fuji A. Effect of friction welding condition and weld faying surface properties on tensile strength of friction welded joint between pure titanium and pure copper. J Solid Mech Mater Eng 2011;5(12):849–65. [33] Kimura M, Iijima T, Kusaka M, Kaizu K, Fuji A. Joining phenomena and tensile strength of friction welded joint between pure titanium and low carbon steel. Mater Des 2014;55:152–64. [34] Nishida H, Ogura T, Hatano R, Hirose A. Effects of thermal history on the interface of A3003/SUS304 FSWed lap joints. J Light Met Weld 2015;53(12):510–5 [in Japanese]. [35] Japanese Industrial Standards Committee. JIS Z 3175 Methods of test and classification of quality evaluations for friction welded joints on dissimilar metallic materials. Tokyo: Japanese Industrial Standards Committee; 2016 [in Japanese]. [36] Hasegawa T, Yakou T, Shimizu M, Karashima S. The effect of deformation temperature on the Bauschinger effect in polycrystalline aluminium. Trans Jpn Inst Met 1976;17(7):414–8. [37] Hidayetoglu TK, Pica PN, Haworth WL. Aging dependence of the Bauschinger effect in aluminum alloy 2024. Mater Sci Eng 1985;73:65–76.
Contents lists available at ScienceDirect
Journal of Manufacturing Processes journal homepage: www.elsevier.com/locate/manpro
Effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joint between pure aluminium and AISI 304 stainless steel M. Kimura a,∗ , K. Suzuki b,1 , M. Kusaka a , K. Kaizu a a b
Department of Mechanical Engineering, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan
a r t i c l e
i n f o
Article history: Received 26 September 2016 Received in revised form 22 November 2016 Accepted 3 December 2016 Keywords: Friction welding Aluminium Austenitic stainless steel Friction welding condition Joint efficiency Bend ductility
a b s t r a c t Aluminium (Al) and stainless steel have such some advantages as high functionalities for the industrial usage. However, the dissimilar joints have severe problems such as generating the intermediate layer consisting of a brittle intermetallic compound (IMC interlayer) during welding process. Friction welding is very useful for making of dissimilar joint. This paper described the effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joints between pure Al (CPAl) and austenitic stainless steel (AISI 304). The joining phenomena during the friction process such as joining behaviour, friction torque, temperature changes at the weld interface, and transitional changes of the weld interface were investigated. The effects of friction time and forge pressure on the tensile strength and bend ductility of joints were also investigated, and the metallurgical characteristics of those were observed. The joint, which had high joint efficiency, the fracture on the CP-Al side with no crack at the weld interface, and no IMC interlayer on the weld interface, could be successfully achieved. Then, the joint should be made with a high forge pressure of 150 MPa, the opportune friction time at which the temperature on the weld interface reached about 573 K or higher, and those friction welding conditions were suggested for obtaining good joints with high joint efficiency and the bend ductility of 90◦ . © 2016 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.
1. Introduction Aluminium (Al) and its alloys (referred to as Al-system material) are well-known materials that have highly attractive characteristics in terms of metallurgical and mechanical properties, e.g., high electrical and thermal conductivity, excellent corrosion resistance, light weight, and high specific strength. They are widely used for important structural components in automobiles, aerospace, and so on. On the other hand, fusion welding between Al-system material and such other materials as steel [1–3], copper (Cu) [1,4], and titanium (Ti) [5] has poor mechanical properties because of the brittle intermetallic compound (IMC) interlayer produced at the joint interface [6]. In addition, fusion welds between Al or its alloys and various steels have severe problems, e.g. generating of blowhole and crack at the joint interface [1–3]. However, a joining between Al-system materials and other materials has some superior inter-
∗ Corresponding author. E-mail address: [email protected] (M. Kimura). 1 Present: Mitsubishi Electric Corporation, Himeji Works, Japan.
est items, because joints of a combination with dissimilar materials have such some advantage points as the low cost solutions for the engineering requirements in the industrial usage. Therefore, a welding process for the joint between Al-system material and other material, which will result in less degradation of the mechanical and metallurgical properties, is urgently required. The solid state joining methods such as diffusion welding, friction welding, and friction stir welding, can be applied to join between Al-system material and other materials. Many researchers have reported that the mechanical and metallurgical properties of the friction welded joints of Al-system materials and various carbon steels [7–13] or stainless steels [16–23] show desirable characteristics. For example, the friction welding condition for the joint that had the good tensile strength of the joint between Al-system materials and various carbon steels was individually demonstrated as following combinations: various Al alloy and various steels by Elliott and Wallach [7], and Yilmaz et al. [8], pure Al and mild steel by Kumar et al. [9], AA5052 Al alloy and mild steel by Lee et al. [10] and Yamamoto et al. [11], and AA6061 Al alloy and mild carbon steel by Ochi et al. [12] and Taban et al. [13]. Additionally, the joint strength of friction stir spot welded joint between AA6061
http://dx.doi.org/10.1016/j.jmapro.2016.12.001 1526-6125/© 2016 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
117
Table 1 Chemical compositions and mechanical properties of materials used. (a) CP-Al Chemical compositions, wt.% Fe Si
Cu
Mg
V
Ti
Al
Mechanical properties UTS, MPa 0.2% YS, MPa
El., %
0.03
0.011
0.02
0.01
0.01
bal.
120
27
0.1
118
(b) 304SS Chemical compositions, wt.% C Mn Si
P
S
Ni
Cr
Fe
Mechanical properties UTS, MPa 0.2% YS, MPa
El., %
0.05 0.07
0.03 0.03
0.02 0.03
8.1 8.18
18.22 18.48
bal. bal.
680 670
47 57
1.54 1.5
0.46 0.49
Al alloy and mild steel by Sun et al. [14] as well as that of friction stir welded joint between AA5052 Al alloy and high strength low alloy steel by Ramachandran et al. [15] were also investigated. In those ways, some researchers have reported that the joining of Alsystem materials and various carbon steels could be successfully achieved and a relatively good joint was obtained. Furthermore, the characteristics of joints between Al-system materials and various stainless steels were investigated. For example, Sahin [16] and Sunay et al. [17] studied the joint strength and the characteristics of the IMC interlayer of the joint between pure Al and American Iron and Steel Institute (AISI) standard type 304 austenitic stainless steel. Shubhavardhan and Surendran [18] investigated the properties of the IMC interlayer of the joint for this combination, and Alves et al. [19] reported the measuring method of the weld interface of the joint for this combination. Fukumoto et al. [20] described the details microstructure at the adjacent region of the weld interface of the joint for this combination. Reddy et al. [21] and Ashfaq et al. [22] explained the joint strength and the characteristics of the IMC interlayer of the joint between AA6061 Al alloy and 304 stainless steel. Paventhan et al. [23] tried the optimization for the friction welding condition of the joint between AA6082 Al alloy and 304 stainless steel. Nevertheless, the joining mechanism of friction welding between Al-system materials and various stainless steels has not been fully clarified, so that the friction welding conditions for material combinations are determined by trial and error. That is, the joining mechanism of friction welding for dissimilar materials was not clarified, and the theoretical friction welding condition that the joint does not fracture from the weld interface was not presented. Moreover, the joining mechanism of friction welding for dissimilar materials differs from that of similar materials, since the mechanical properties such as the tensile strength and the thermal properties such as the thermal conductivity are different from the combinations of similar materials. Naturally, it is considered that the friction welding condition of the joint without the fracture from the weld interface will be differed with between the combination of Al-system materials on carbon steels and the combination of Alsystem materials on stainless steels. To determine the theoretical friction welding conditions, it is very essential to clarify the joining phenomena and the joint mechanical properties. In particular, the clarifications of the joining mechanism are strongly required concerning the weldability between the Al-system materials and various stainless steel, because an expansion in the use of the joint with those combination is expected and widely used in various component parts such as spacecraft parts. In previous works [24–26], the authors clarified the joining mechanism during the friction welding process of similar material combinations that were various carbon steels [24] or Al-system materials [25,26]. Furthermore, the authors also clarified the joining mechanism of some dissimilar material joints as following combinations: pure Al and pure Cu [27], Al-system materials and low carbon steel (LCS) [28,29], Cu-system materials and low carbon steel [30,31], pure Cu and pure Ti [32], and pure Ti and LCS [33]. If combinations of dissimilar materials between Al-system materials
475 435
and stainless steels can be joined using the same welding method as that shown in previous reports [24–33], the joining mechanism will be clarified. Then, it will be possible to clarify the difference of the friction welding condition of the joint between Al-system materials and LCS [28,29]. Therefore, to weld Al-system materials and stainless steels by the experiment is necessary for clarification of the joining mechanism. Based on the above background, the authors have been carrying out research to clarify the joining mechanism during the friction process of the dissimilar joint. The authors investigate the joining phenomena during the friction process of friction welds between pure Al and AISI 304 stainless steel of a typical austenitic stainless steel in the present work. The authors show the tensile strength and bend ductility of the friction welded joints under various friction welding conditions, especially the effects of friction time and forge pressure on those. Moreover, the authors show the theoretical friction welding condition for joints that had the bend ductility of 90◦ with no crack at the weld interface by bending test as well as the fracture on the CP-Al side by tensile test. 2. Experimental procedure 2.1. Materials and specimen shapes The materials used were commercially pure Al (type JIS A1070BD-F, referred to as CP-Al) and AISI 304 austenitic stainless steel (JIS SUS304, referred to as 304SS) in 16 mm diameter rods. The chemical compositions and the ultimate tensile strength (UTS), the 0.2% yield strength (YS), and the elongation (El.) for materials used were shown in Table 1. In this case, two kinds of 304SS having slightly different tensile properties were used for this experiment since they were purchased at different times. Both rods were used for this experiment as received condition. Those rods were machined to 12 mm in a diameter of the weld faying (contacting) surface. The temperature changes at the centreline, half radius, and periphery locations of 1.0 mm longitudinal direction from the weld faying surface were measured using the 304SS specimen for clarification of the temperature during the friction process, of which was shown in Fig. 1. In this connection, although the temperature
Fig. 1. Shape and dimensions of friction welding specimen of 304SS for measuring temperature change at weld interface.
118
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
Fig. 2. Schematic diagrams of bending test methods.
on the weld interface will be able to estimate as those measuring positions or higher, the sufficient data to the clarification of the joining phenomena could be obtained in order to understand the temperature distribution of the radius direction on the weld interface. The details of the specimen shape for measuring temperature changes have been described in a previous report [28]. All weld faying surfaces of the specimens were polished by a surface grinding machine before joining to eliminate the effect of surface roughness on the joint mechanical properties [32]. 2.2. Friction welding method A continuous (direct) drive friction welding machine was used for the joining. During the friction welding operations, the friction welding condition was set to the following combinations: a friction speed of 27.5 s−1 (1650 rpm), a friction pressure of 30 MPa, a range of friction times from 0.04 to 3.0 s, a range of forge pressures from 30 to 150 MPa, and a forge time of 6.0 s. To observe the joining phenomena during the friction process and to obtain the joint without the braking deformation, the authors carried out three experimental methods as follows. (1) A conventional friction welding method that have a brake system when the friction time expired. (2) The welding method that the fixed side specimen is simultaneously and forcibly separated from the rotating side specimen when the friction time expired. This welding method was performed for observation of the transitional changes of the weld interface. (3) The welding method that the relative speed on the weld interface between both specimens is simultaneously decreased to zero when the friction time expired. This welding method was used to prevent braking deformation during rotation stop. Then, this welding method was performed for measurement of the mechanical and metallurgical properties of joints. In this connection, the friction torque was measured with a load-cell, and the temperatures were measured with mineral insulated thermocouples composed with a chromel–alumel, those were inserted to holes of the 304SS specimen. Then, the friction torque and temperature were recorded with a personal computer through an A/D converter with a sampling time of 0.001 s. Furthermore, when joints were made by the experimental method of (1), i.e. the conventional friction welding method, the rotation of the specimen is not instantly stopping. That is, it was necessary of the braking time for rotation stop, because the rotation of the specimen is not stopped completely at setting friction time. Hence, the experimental method of (3) was carried out for making of the joint with setting friction time, and those joints were used for measurement
of the mechanical and metallurgical properties. The details of these methods have been also previously described [28]. 2.3. Tensile and bending test methods All joint tensile test specimens were machined to 12 mm in the diameter and 66 mm in the parallel length. That is, all flash (burr or collar), which was exhausted from the weld interface during the friction welding process, were removed from joints for joint tensile test specimens. Moreover, the joint bending test was carried out for clarification of the bend ductility of joint. The flash and the chucking part of both sides were removed and machined to a 12 mm diameter for a bending test. By the way, three-point or four-point bending could not be applied satisfactorily, because of the significant difference in strength between the CP-Al and 304SS base metals. Consequently, the 304SS side was held stationary in a vice and the CP-Al side was bent to a maximum angle of 90◦ as shown in Fig. 2a (referred to as a single direction bending test). Furthermore, the joint with the bend ductility of 90◦ was bent to the opposite direction to 90◦ as almost straight bar shape, and then this joint was bent to a maximum angle of 90◦ . That is, the joint with the bend ductility of 90◦ was also bent to the opposite direction with a maximum angle of 180◦ as shown in Fig. 2b (referred to as a reverse direction bending test). Then, the incidence of crack at the joint interface was observed in each case. The joint tensile and bending tests were performed with as-welded condition at room temperature. 2.4. Hardness test and SEM observation methods Vickers hardness test at low test force, i.e., the Vickers microhardness (referred to as Vickers hardness), was carried out at room temperature for clarification of the joint properties. Measuring load was 2.94 N (0.3 kgf), and the measuring range was about 10 mm from the weld interface to both sides. SEM observation via EDS analysis was performed to analyze the chemical composition on the adjacent region of the weld interface. The fractured surface of the joint after joint tensile testing was analyzed using X-ray diffraction analysis and SEM observation via EDS analysis. 3. Results 3.1. Observation of joining phenomena during friction process 3.1.1. Relationship between joining behaviour and friction torque Fig. 3 shows the relationship between the joining behaviour and the friction torque. Photos 1)–6) in Fig. 3a correspond to the friction torque of (1)–(6) in Fig. 3b, respectively. Photo 1) shows the state at the weld faying surfaces as they contacted each other,
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
119
Fig. 3. Joining behaviour and friction torque curve during friction process.
then the friction torque was increased. The CP-Al side was slightly upset (deformed) as shown in Photo 2), and then the friction torque reached the initial peak of (3) in Fig. 3b. In this instance, the initial peak torque was approximately 15 Nm, and the elapsed time for the initial peak was about 0.5 s. The numerical value of the initial peak torque was almost similar to that of the joint between CP-Al and LCS (referred to as CP-Al/LCS joint) at the same friction pressure [28] and this elapsed time for the initial peak was shorter than that of its joint. Thereafter, the upsetting and the flash of CP-Al increased with friction time though the 304SS side was not upset, as shown in photos (4) and (5) in Fig. 3a. 3.1.2. Temperature change during friction process Fig. 4 shows the temperature changes with the friction torque during the friction process. All measured temperatures increased with friction time. Although all measured temperatures were almost the same before the friction torque reached the initial peak, the temperature after this friction time was high in the order of the periphery, half radius, and centreline locations. However, the difference in each temperature was about 50 K or less at a friction time of about 1.0 s or longer, and the temperature of the half radius location at this friction time was about 573 K (300 ◦ C). Then, when a
Fig. 4. Relationship between friction time and temperature changes at various measured locations of 304SS side during friction process, in relation to friction torque curve.
Fig. 5. Appearances of weld interfaces after welding at various friction times.
120
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
Fig. 6. Relationship between friction time and joint efficiency of joints, in relation to friction torque; forge pressure of 30 MPa.
friction time was 2.0 s, those temperatures reached to about 723 K (450 ◦ C). Thereafter, the temperature of the periphery location was a little higher than that of others, and then those reached to about 750 K (477 ◦ C) at a friction time of 3.0 s. 3.1.3. Transitional changes of weld interface Fig. 5 shows the examples of the appearances of the weld interfaces after welding at various friction times. When a friction time was 0.04 s, i.e. both specimens had been rotated once, the concentric rubbing marks were observed at the half radius portion of the weld interface of both sides. CP-Al transferred to the weld interface on the 304SS side. When a friction time was 0.2 s, the concentric rubbing marks on the CP-Al side were extended to the central and peripheral portions, and the transferred CP-Al on the 304SS side increased. Then, almost whole weld interface on the 304SS side had the transferred CP-Al at a friction time of 0.5 s, i.e. the friction torque close to the initial peak, and the flash on the CP-Al side was increased. The transferred CP-Al on the peripheral portion of the weld interface was less than that of other portions. Thereafter, the weld interface on the 304SS side was almost similar although the flash on the CP-Al side was increased with friction time. Also, the 304SS flash was hardly observed at all friction times. Based on these results, it was clarified that the entire weld interface of the 304SS side had the transferred CP-Al when the friction torque reached the initial peak. 3.2. Investigation of mechanical and metallurgical characteristics 3.2.1. Relationship between tensile strength of joint and friction time Fig. 6 shows the relationship between the friction time and the joint efficiency of joints, and those were plotted alongside the friction torque curve. The joint efficiency was defined as the ratio of joint tensile strength to the ultimate tensile strength of the CPAl base metal. Fig. 7 shows examples of the appearances of the joint tensile tested specimens. In this instance, forge pressure was applied at an identical friction pressure, i.e. 30 MPa. The joint efficiency at a friction time of 0.2 s was approximately 15%. The joint fractured at the weld interface as shown in Fig. 7a, although it had a little CP-Al adhering on the weld interface of the 304SS side. Incidentally, the CP-Al and 304SS were not joined before a friction time of 0.2 s because a sufficient quantity of friction heat for welding could not be produced. The joint efficiency increased with increasing friction time, and then it was approximately 63% efficiency at a friction time of 0.5 s, i.e. the friction torque close to the initial peak.
Fig. 7. Examples of appearances of joint tensile tested specimens.
However, the joint efficiency had a scattering. Then, the joint efficiency maintained approximately 70% after this friction time. Some joints, which were made with a friction time of 2.0 s or longer, fractured between the weld interface and the CP-Al side (referred to as mixed mode fracture) as shown in Fig. 7b. Thereafter, when joints were made a friction time of 2.5 s or longer, some joints fractured from the CP-Al side as shown in Fig. 7c. The fracture was produced at the near part of the weld interface in the CP-Al side. However, all joints, which had the fracture in the CP-Al side with 100% joint efficiency, were not obtained at a forge pressure of 30 MPa. In contrast, CP-Al/LCS joint fractured on the CP-Al side after the friction time that the friction torque reaches the initial peak [28]. Therefore, it was clarified that the friction welding condition of the joint without the fracture on the weld interface differed between the joint in this study and CP-Al/LCS joint [29]. To clarify the joint characteristics, the joint was performed to SEM observation. Fig. 8 shows the SEM image and EDS analysis result at the peripheral portion of the adjacent region of the weld interface for the joint. In this instance, the joint was made with a friction time of 3.0 s, and the SEM–EDS analysis was performed at the peripheral portion of the weld interface since this portion reached to such a high temperature condition as about 750 K during the friction process as shown in Fig. 4. The distribution lines corresponding to Al, Si, Fe, Cr, and Ni by EDS analysis had no plateau part at the weld interface, i.e., this joint did not have the IMC interlayer, although the weld interface was slightly unclear. The joints with other friction times as well as the other portions of these joints did also not have the IMC interlayer, although the temperature of the radius direction in the weld interface or the reached temperature at the weld interface differed as shown in Fig. 4 (data not shown due to space limitations). In addition, it is considered that the IMC interlayer will be not generated for the joint with a short friction time, since the joint with a long friction time of 3.0 s did not have IMC interlayer. It was able to estimate that the IMC interlayer at the weld interface is not generated this friction time (3.0 s) with the temperature of about 723 K. This thought was also able to estimate from the result, which the IMC interlayer was observed in the friction stir welded joint between AA3003 Al alloy and 304SS with post-weld heat treated at a holding time of about 60 s or longer [34]. Hence, it was clarified that the cause of the joint with the mixed mode fracture was not due to the IMC interlayer at the weld interface, and it was based on the SEM observation level.
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
121
Fig. 8. SEM image and EDS analysis result at peripheral portion of adjacent region of weld interface for joint; friction time of 3.0 s and forge pressure of 30 MPa.
Fig. 9 shows the SEM photographs and analysis results of chemical compositions for the fractured surfaces on CP-Al and 304SS sides of joint tensile tested specimens, respectively. This joint was made with a friction time of 1.5 s and a forge pressure of 30 MPa. Then, the peripheral portion of the fractured surface was observed. Only Al was detected on the fractured surface of the CP-Al side, and that was shown in Fig. 9a. On the other hand, Fe, Cr and Ni of which were corresponded to 304SS, and Al was detected on the fractured surface of the 304SS side (see Fig. 9b). Additionally, other portions on the fractured surfaces of this joint as well as that with another friction times had similar chemical compositions. Thus, the IMC interlayer was not observed in the joint, and it was clarified that the CP-Al and 304SS sides were not completely joined under this forge pressure (30 MPa). 3.2.2. Relationship between tensile strength of joint and forge pressure To improve the joint efficiency, the effect of forge pressure on joint efficiency was investigated. Fig. 10 shows the relationship between the forge pressure and the joint efficiency of joints at various friction times. When joints were made with a friction time of 0.6 s as shown in Fig. 10a, the joint efficiency at a forge pressure of 30 MPa was approximately 70% although it had scattering, and those fractured at the weld interface as shown in Fig. 7a. The joint efficiency slightly increased to approximately 80% with increasing forge pressure. The fractured point of the joint changed from the mixed mode fracture to the CP-Al side fracture. Then, when joints were made with a forge pressure of 150 MPa, all joints fractured on the CP-Al side, of which was shown in Fig. 11. In addition, the fractured point of this joint occurred in the position of the CP-Al side with about 10 mm longitudinal distance from the weld interface, and the weld interface had no defect such as cracks (compare Fig. 7c and Fig. 11).
Fig. 9. SEM–EDS analysis results at peripheral portion of fractured surfaces of joint tensile tested specimens; friction time of 1.5 s, and forge pressure of 30 MPa.
That is, the fractured point of this joint differed in comparison with that of a forge pressure of 30 MPa, although joints also fractured from the CP-Al side. The similar results were also obtained when the joint was made with friction times of 1.0 and 1.5 s as shown in Fig. 10b and c, although the joint efficiency differed. Furthermore, all joints at those friction times with a forge pressure of 135 MPa or higher fractured from the CP-Al side as shown in Fig. 11. Fig. 12 shows the appearance of the cross-section for the tensile tested specimen, which fractured in the CP-Al side. In this instance, the joint was made with a friction time of 1.0 s and a forge pressure of 150 MPa. The weld interface of the joint after tensile testing had neither a not-joined region nor defects such as cracks, and the fracture was produced at the part of the longitudinal direction over about 10 mm distance from the weld interface in the CP-Al side. That is, CP-Al and 304SS were tightly joined. Therefore, it was clarified that the joint with the CP-Al side fracture was obtained with such a high forge pressure as 150 MPa.
122
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
Fig. 12. Appearance of cross-section for tensile tested specimen with CP-Al side fracture; friction time of 1.0 s and forge pressure of 150 MPa.
Fig. 13. Vickers hardness distributions across weld interface of joints; friction time of 1.0 s and forge pressure of 30 and 150 MPa.
Fig. 10. Relationship between forge pressure and joint efficiency of joints at various friction times.
Fig. 11. Appearance of joint tensile tested specimen with CP-Al side fracture.
Fig. 13 shows the Vickers hardness distributions across the weld interface on the periphery location of joints with a friction time of 1.0 s. The joint with a forge pressure of 30 MPa had a softened area that extended about 4.0 mm in the longitudinal direction of the CPAl side. However, the joint with a forge pressure of 150 MPa did not have a softened area. The joints with the CP-Al side fracture
at other friction times as well as the other measuring locations of this joint did also not have the softened area. Hence, it was clarified that the joint had the fracture on the CP-Al side without 100% joint efficiency although it did not have the softened area on the adjacent region of the weld interface. The cause of the joint with the CP-Al side, of which did not have 100% joint efficiency, will be described later. Incidentally, the hardness of the 304SS base metal differed since used 304SS had different mechanical properties as shown in Table 1. 3.2.3. Relationship between joint bend ductility and forge pressure Based on the above results, the joint that was made with a friction time of 0.6 s or longer and a forge pressure of 150 MPa had the fracture in the CP-Al side as shown in Fig. 11. To clarify the joint properties in details, the joints were bent to a maximum angle of 90 ◦ by a single direction bending test as shown in Fig. 2a. Fig. 14 shows examples of the appearances of joint bending tested specimens by a single direction bending test. In this case, the joints were made with friction times of 0.6, 1.0, and 1.5 s, and a forge pressure of 120 MPa or higher, since those joints had the CP-Al side fracture as shown in Fig. 10. When joints were made with forge pressures of 120 and 135 MPa, some of those had the bend ductility of 90◦ with no crack at the weld interface regardless of friction time, and that was shown in Fig. 14b. However, some joints had cracks at the
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
123
friction heat, although the joint had the fracture on the CP-Al side by tensile test. However, the joint at a friction time of 1.0 s had the bend ductility of 90◦ in reverse direction with no crack at the weld interface as shown in Fig. 15b. That is, the sound joint was successfully achieved. Additionally, it was clarified that this joint was satisfied with the superlative grade of the classification of quality for friction welded joints on dissimilar metallic materials in JIS Z 3175 [35]. On the other hand, when the joint was made at a friction time of 1.5 s, it also had cracks at the weld interface. Hence, a friction time should be set to 1.0 s, because the softened area on the adjacent region of the weld interface of the joint will be expanded due to long friction time.
4. Discussion
Fig. 14. Appearances of joint bending tested specimens by single direction bending test.
Fig. 15. Appearances of joint bending tested specimens by reverse direction bending test; forge pressure of 150 MPa.
weld interface as shown in Fig. 14a. Hence, the joint with those forge pressures was not a sound joint. On the other hand, all joints, which were made with a forge pressure of 150 MPa, had the bend ductility of 90◦ with no crack at the weld interface (Fig. 14b). That is, the joints that were made with this forge pressure (150 MPa) had the fracture in the CP-Al side and the bend ductility of 90◦ . Furthermore, the joint bending test specimens by a single direction bending testing were bent with 180◦ of a reverse side as shown in Fig. 2b, for clarification of the joint properties under the more rigorous bending condition. Fig. 15 shows examples of the appearances of joint bending tested specimens by a reverse direction bending test. In this case, those joints were made with a forge pressure of 150 MPa. When the joint was made at a friction time of 0.6 s, it had cracks at the weld interface (Fig. 15a). Therefore, it was considered that the joint with this friction time did not have enough
Based on the above consequences, the joint that was made with a friction time of 1.0 s and a forge pressure of 150 MPa, had the fracture in the CP-Al side and the bend ductility of 90◦ . In addition, the joint had scarcely a softened area of the CP-Al side (see Fig. 13). Nevertheless, the joint efficiency of 100% was not obtained. Incidentally, the joining phenomena during the friction process of CP-Al/LCS joint [28] resembled those of the combination of the joint in this study. In other words, only the CP-Al side upset but 304SS side in this study hardly upset, which was showed in Fig. 3a. Therefore, the joint that did not have 100% joint efficiency was considered the change of the mechanical properties of the CP-Al base metal, because the fractured point of the joint occurred at the CP-Al side with about 10 mm longitudinal distance from the weld interface (see Fig. 11). That is, the cause of the joint, which was not obtained the joint efficiency of 100%, is able to consider the Bauschinger effect of the CP-Al base metal [28], and the difference of the anisotropic properties for as-manufactured condition [26] of the CP-Al base metal. First, CP-Al/LCS joint had the result of the joint efficiency decreased with increasing forge pressure in a previous report [28]. When the compressive stress was higher than the yield stress of the CP-Al base metal, the tensile strength of the CP-Al base metal with a high compressive load was lower than the yield strength with no compressive load. Moreover, the decreasing of the tensile rate of the CP-Al base metal could estimate at other temperature [28], as well as the Bauschinger effect in Al-system materials was affected at various temperatures [36,37]. Hence, one of the causes for decreasing joint efficiency of CP-Al/304SS joint was due to the change of the properties for the CP-Al base metal like the Bauschinger effect. Second, it was considered the difference of the tensile strength for the CP-Al base metal at the longitudinal and radial directions, since the flash of the CP-Al of the joint was exhausted to the radial directions from the longitudinal directions at the adjacent region to the weld interface (Figs. 3 and 5), and the fractured point of the joint was not the softened area of the CP-Al side (Fig. 12). Fig. 16 shows the cross-sectional appearances of the adjacent region of the weld interface of joints at various forge pressures. Those joints were made with a friction time of 1.0 s. The CP-Al side was pressed towards the longitudinal direction with increasing forge pressure although the quantity of flash of CP-Al almost maintained in spite of that increasing. Then, the fibre structure of the CP-Al base metal with corresponding to the longitudinal direction flowed to the radius (outer surface) direction from the longitudinal direction. That is, that fibre structure of the CP-Al base metal changed towards the radius direction at the adjacent region of the weld interface on the CP-Al side. Actually, the tensile strength of the radial direction of the Al alloy and pure Cu rods were slightly lower than that of the longitudinal direction, and that was described in previous reports [26,32]. Hence, it was considered that the joint was not obtained the joint efficiency of 100%, and one of the causes was also the difference of the anisotropic
124
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125
Fig. 16. Cross-sectional appearances of adjacent region of weld interface for joints at various forge pressures; friction time of 1.0 s.
properties with as-manufactured condition of the CP-Al base metal. Incidentally, similar results of both the change of the properties for the CP-Al base metal like the Bauschinger effect and the difference of the anisotropic properties were also obtained in pure Cu/pure Ti joint [32] as well as CP-Al/LCS joint [28]. The fact that the joint did not have 100% joint efficiency was due to the decrease in the tensile strength of the CP-Al base metal by the Bauschinger effect as well as the difference of the anisotropic properties, although further investigation is necessary to elucidate the detailed mechanical properties of joints. However, a high forge pressure such as 150 MPa is necessary for the joint since it had cracks at the weld interface when it was made with such a forge pressure of 90 MPa (see Figs. 10, 14 and 15). Therefore, to obtain good joint for higher joint efficiency and bend ductility, the joint should be made with a high forge pressure of 150 MPa, and with the opportune friction time that the temperature on the weld interface reached to about 573 K or higher. This friction welding condition differed with CP-Al/LCS joint [28]. Hence, it is necessary to note in the selection of the friction welding condition for making good joint between Al-system materials and various steels.
5. Conclusions This report described the effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joint between pure aluminium (CP-Al) and austenitic stainless steel (JIS SUS304, 304SS). The following conclusions are provided.
(1) When joints were made at a friction pressure of 30 MPa with a friction speed of 27.5 s−1 , the upsetting (deformation) occurred at the CP-Al base metal. CP-Al transferred to the half radius region of the weld interface on the 304SS side, and then it transferred towards the entire weld interface. The temperature on the weld interface increased with friction time, and it reached to 573 K or over at a friction time of 0.6 s or longer. (2) When joints were made at a friction time of 0.6 s, i.e. the friction torque close to the initial peak, it had the joint efficiency of approximately 70% and fractured at the weld interface. Some joints, that were made at a friction time of 2.0 s or longer, had the mixed mode fracture (between the CP-Al side and the 304SS side) and the CP-Al side fracture. However, the joint efficiency of 100% was not obtained because the CP-Al side at the adjacent region of the weld interface softened. (3) When joints were made with a forge pressure of 150 MPa, all joints fractured from the CP-Al side, although those had the joint efficiency of approximately 80%. Nevertheless, the joint had hardly a softened area at the adjacent region to the weld
interface of the CP-Al side. Those joints did also not have the intermetallic compound (IMC) interlayer on the weld interface. (4) The joints, which were made at a friction time of 1.0 s with a forge pressure of 150 MPa, had the bend ductility of 90◦ in a single direction with no crack at the weld interface. This joint had also the bend ductility of 90◦ in reverse direction with no crack. (5) The fact that the joint did not have 100% joint efficiency was due to the decrease in the tensile strength of the CP-Al base metal that was occurred by the Bauschinger effect as well as the difference of the anisotropic properties. In conclusion, to obtain good joint for higher joint efficiency and bend ductility, the joint should be made with such a high forge pressure as 150 MPa, and with the opportune friction time that the temperature on the weld interface reached to about 573 K or higher. Acknowledgements The authors wish to thank the staff members of the Machine and Workshop Engineering at the Graduate School of Engineering, University of Hyogo. Also, the authors wish to thank Emeritus Prof. Dr Akiyoshi Fuji and technical officer Mr Harumi Hashimoto in Kitami Institute of Technology for their kind and aggressive assisting to this study. References [1] Technical Committee on Structural Transition Joint. Studies on the properties of aluminium alloy-steel transition pieces for structural transition joint (STJ) of ship superstructure. J Light Met Weld Constr 1978;16(8):345–64 [in Japanese]. [2] Ueda Y, Niinomi M. On the alloy layers formed by the reaction. J Jpn Inst Met 1978;42(6):543–9 [in Japanese]. [3] Sasabe S, Matsumoto T, Iwase T, Hattori Y, Miono T. Study on the factors in creating the IMC free region—dissimilar metal joining of aluminum alloys to steel in MIG-braze welding by using the advanced hot-dip aluminized steel sheet. Q J Jpn Weld Soc 2010;28(1):54–60 [in Japanese]. [4] Dawson RJC. Welding of copper and copper-base alloys. Weld Res Counc Bull 1983;287:1–17. [5] The Japan Titanium Society. Titanium. Tokyo: Kogyo Chosakai Publishing; 2007. p. 268–9 [in Japanese]. [6] American Welding Society. Welding handbook, vol. 4, 7th ed. American Welding Society: Miami. FL; 1982. p. 537–8. [7] Elliott S, Wallach ER. Joining aluminium to steel part 2—friction welding. Met Constr 1981;13(4):221–5. [8] Yilmaz M, C¸öl M, Acet M. Interface properties of aluminum/steel frictionwelded components. Mater Charact 2003;49:421–9. [9] Kumar S, Kumar R, Singla YK. To study the mechanical behaviour of friction welding of aluminium alloy and mild steel. Int J Mech Eng Rob Res 2012;1(3):43–50. [10] Lee WB, Yeon YM, Kim DU, Jung SB. Effect of friction welding parameters on mechanical and metallurgical properties of aluminium alloy 5052-A36 steel joint. Mater Sci Technol 2003;19:773–8. [11] Yamamoto N, Takahashi M, Aritoshi M, Ikeuchi K. Effect of intermetallic compound layer on bond strength of friction-welded interface of Al-Mg 5052 alloy to mild steel. Q J Jpn Weld Soc 2005;23(2):352–8 [in Japanese].
M. Kimura et al. / Journal of Manufacturing Processes 25 (2017) 116–125 [12] Ochi H, Ogawa K, Yamamoto Y, Suga Y. Bending tensile torsional strength of friction welded joint of 6061 aluminum alloy and S45C carbon steel. J Jpn Soc Fract Strength Mater 1994;28(4):143–54 [in Japanese]. [13] Taban E, Gould JE, Lippold JC. Dissimilar friction welding of 6061-T6 aluminum and AISI 1018 steel: properties and microstructural characterization. Mater Des 2010;31:2305–11. [14] Sun YF, Fujii H, Takaki N, Okitsu Y. Microstructure and mechanical properties of dissimilar Al alloy/steel joints prepared by a flat spot friction stir welding technique. Mater Des 2013;47:350–7. [15] Ramachandran KK, Murugan N, Kumar SS. Friction stir welding of aluminum alloy AA5052 and HSLA steel. Weld J 2015;94(9):291s–300s. [16] Sahin M. Joining of stainless-steel and aluminium materials by friction welding. Int J Adv Manuf Technol 2009;41:487–97. [17] Sunay TY, Sahin M, Altintas S. The effects of casting and forging processes on joint properties in friction-welded AISI 1050 and AISI 304 steels. Int J Adv Manuf Technol 2009;44:68–79. [18] Shubhavardhan RN, Surendran S. Friction welding to join dissimilar metals. Int J Emerg Technol Adv Eng 2012;2(7):200–10. [19] Alves EP, Neto FP, An CY, da Silva EC. Experimental determination of temperature during rotary rriction welding of AA1050 aluminum with AISI 304 stainless steel. J Aerosp Technol Manag 2012;4(1):61–7. [20] Fukumoto S, Tsubakino H, Aritoshi M, Tomita T, Okita K. Dynamic recrystallisation phenomena of commercial purity aluminium during friction welding. Mater Sci Technol 2002;18(2):219–25. [21] Reddy GM, Rao AS, Mohandas T. Role of electroplated interlayer in continuous drive friction welding of AA6061 to AISI 304 dissimilar metals. Sci Technol Weld Joining 2008;13(7):619–28. [22] Ashfaq M, Sajja N, Rafi HK, Rao KP. Improving strength of stainless steel/aluminum alloy friction welds by modifying faying surface design. J Mater Eng Perform 2013;22(2):376–83. [23] Paventhan R, Lakshminarayanan PR, Balasubramanian V. Prediction and optimization of friction welding parameters for joining aluminium alloy and stainless steel. Trans Nonferrous Met Soc China 2011;21:1480–5. [24] Kimura M, Kusaka M, Seo K, Fuji A. Observation of joining phenomena in friction stage and improving friction welding method. JSME Int J Ser A 2003;46(3):384–90. [25] Kimura M, Kusaka M, Seo K, Fuji A. Joining phenomena during friction stage of A7075-T6 aluminium alloy friction weld. Sci Technol Weld Joining 2005;10(3):378–83.
125
[26] Kimura M, Choji M, Kusaka M, Seo K, Fuji A. Effect of friction welding conditions on mechanical properties of A5052 aluminium alloy friction welded joint. Sci Technol Weld Joining 2006;11(2):209–15. [27] Kimura M, Inui Y, Kusaka M, Kaizu K, Fuji A. Joining phenomena and tensile strength of friction welded joint between pure aluminum and pure copper. Mech Eng J 2015;2(1). No. 14-00328. [28] Kimura M, Ishii H, Kusaka M, Kaizu K, Fuji A. Joining phenomena and joint strength of friction welded joint between pure aluminium and low carbon steel. Sci Technol Weld Joining 2009;14(5):388–95. [29] Kimura M, Ishii H, Kusaka M, Kaizu K, Fuji A. Joining phenomena and joint strength of friction welded joint between aluminium-magnesium alloy (AA5052) and low carbon steel. Sci Technol Weld Joining 2009;14(7):655–61. [30] Kimura M, Kusaka M, Kaizu K, Fuji A. Effect of friction welding condition on joining phenomena and tensile strength of friction welded joint between pure copper and low carbon steel. J Solid Mech Mater Eng 2009;3(2):187–98. [31] Kimura M, Kasuya K, Kusaka M, Kaizu K, Fuji A. Effect of friction welding condition on joining phenomena and joint strength of friction welded joint between brass and low carbon steel. Sci Technol Weld Joining 2009;14(5):404–12. [32] Kimura M, Saitoh Y, Kusaka M, Kaizu K, Fuji A. Effect of friction welding condition and weld faying surface properties on tensile strength of friction welded joint between pure titanium and pure copper. J Solid Mech Mater Eng 2011;5(12):849–65. [33] Kimura M, Iijima T, Kusaka M, Kaizu K, Fuji A. Joining phenomena and tensile strength of friction welded joint between pure titanium and low carbon steel. Mater Des 2014;55:152–64. [34] Nishida H, Ogura T, Hatano R, Hirose A. Effects of thermal history on the interface of A3003/SUS304 FSWed lap joints. J Light Met Weld 2015;53(12):510–5 [in Japanese]. [35] Japanese Industrial Standards Committee. JIS Z 3175 Methods of test and classification of quality evaluations for friction welded joints on dissimilar metallic materials. Tokyo: Japanese Industrial Standards Committee; 2016 [in Japanese]. [36] Hasegawa T, Yakou T, Shimizu M, Karashima S. The effect of deformation temperature on the Bauschinger effect in polycrystalline aluminium. Trans Jpn Inst Met 1976;17(7):414–8. [37] Hidayetoglu TK, Pica PN, Haworth WL. Aging dependence of the Bauschinger effect in aluminum alloy 2024. Mater Sci Eng 1985;73:65–76.