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AA6101 alloys
Materials Today: Proceedings xxx (xxxx) xxx
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Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys G. Swaminathan a,⇑, S. Sathiyamurthy b a b
Assistant professor, Department of Mechanical Engineering, SRMIST, Chennai 89, India Professor, Department of Automobile Engineering, Easwari Engineering College, Chennai 89, India
a r t i c l e
i n f o
Article history: Received 10 June 2019 Received in revised form 11 September 2019 Accepted 13 September 2019 Available online xxxx Keywords: Light-weight Process control variables Tensile properties Tool profile Microstructure Rupture behaviors
a b s t r a c t In this work, flaw free joints of AA7075 and AA6101 alloy 6 mm of plate’s thickness were butt jointed using FS welding. The FS welding has been done at various combinations of process parameters. The quality of the joints is influenced by process variables like tool rotational speed, axial force, welding speed and tool profile. The effect of these variables on tensile properties, microstructure structure and rupture behavior of the welded joints are discussed. Tool revolving speed and tool profile play key control on tensile properties and obtain the extensive requirements in the field of light-weight building construction. Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Materials Engineering and Characterization 2019.
1. Introduction The need for greater energy efficiency in today’s LEED (Leadership in Energy and Environmental Design) certified buildings are fueling the use of sustainable, corrosion-resistant materials from floor to ceiling. In commercial and residential buildings, we offer higher-strength specialty material solutions that can reduce overall project lifecycle costs. Friction stir welding offers the likelihood to deliver superior properties joints with short process durations and no extra joining components like filler rod, strap plates, etc., Main benefit of FS welding is that it permits to joining of non-ferrous alloys like aluminum alloys, copper alloys etc., that are considered to be not fusion weldable and of dissimilar material combinations. The quality of a FS welded joint depends on the process control variables of welding conditions, but is weaker than both the base materials. In Friction stir welding process a non consumable tool is to be plunged into the butt surface of the plates with rotation and also it moves along the butting line for weld consolidation and the schematic diagram of friction stir welding as shown in Fig. 1 The tool pin and shoulder are useful for heat generation and blending of materials by stirring and generating the
⇑ Corresponding author. E-mail address: [email protected] (G. Swaminathan).
joint. No melting happens in this phase and the heat generation takes place internally through friction between the material-tool interface and plastic deformation [1]. No cover gas of flux is used in friction stir welding, making the method eco-friendly, energy efficient and green technology. The joining does not require any use of filler metal and therefore any aluminum alloy can be joined without worrying about masterpiece compatibility, which is a problem in fusion welding [2]. In FSW parameters such as tool shape, material, tool rotational velocity, welding velocity and axial force are required to produce efficient friction stir welded joint and achieve a joint effectiveness of 60% [3]. Using different process parameters, joints are acquired in FSW. An ANN model is created using MATLAB and process parameter optimization is performed by comparing the results acquired by designing tests and experimental values of multiple tool pin profiles with distinct process parameters of welding performed on distinct components AA6061, AA6351 and AA6082 [4]. A systematic strategy to the development of the mathematical model to predict the ultimate strength, yield strength and proportion of AA6351 elongation commonly used in industry. The rise in rotational velocity, welding velocity and axial force led to an rise in the ultimate strength and its peak value and then decreased [5]. Effect of FSW process parameters on welded AA6061 aluminum alloy mechanical characteristics. It was found that the tensile strength initially increased with the increase in tool rotational
https://doi.org/10.1016/j.matpr.2019.09.034 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Materials Engineering and Characterization 2019.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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Fig. 1. Schematic Diagram of Friction Stir Welding (Courtesy: S. Sattari [14]).
speed, welding speed and axial force, but the tensile strength decreased after the maximum value was achieved with the further increase of these parameters [6]. Friction stir welding of very thin AA6016-T4 aluminum alloy plates, it was found that the distinction in instrument geometry and welding parameters included significant adjustments in the material flow route during welding as well as in the welding nugget microstructure [7]. Using 33 complete factorial experiment design, the tensile resistance of FSW aluminum alloy A319 was assessed under distinct handling circumstances. Dominant parameter for tensile strength was discovered for tool rotation velocity followed by welded velocity, axial force indicates minimal impact on tensile strength compared to other parameters. A nonlinear regression model that was established to correlate tensile strength was discovered to be helpful in predicting tensile strength [8]. To create the joints, five separate tool pin profiles were used with 3 distinct welding speeds. The straight pin profile with 63 mm/min was discovered to produce better tensile strength than other profile and welding velocity [9]. The FSW of the dissimilar aluminum alloy test was conducted using the cylindrical tool profile and the joint test and the outcome was compared with the base metals [10]. Compare the mechanical and metallurgical characteristics of the welded joints TIG, MIG and Friction dissimilar aluminum alloy AA5083-0 and AA6061-T6 affected by the parameters of the welding method and the
treatment of post-welding aging. Compared to MIG and TIG welded joints, FSW joints are welded. The FSW method therefore displayed superior mechanical and metallurgical characteristics [11–13]. The mechanical characteristics of the Dissimilar Friction stir welded samples have been evaluated and contrasted by optical microscopy with the parent’s base materials and microstructures and a welded specimen, and the welding parameters have a major impact on the mechanical and metallurgical characteristics of the weld [14–17]. Based on the above literature survey, there were a number of discrepancies in friction stir welding of AA7075/AA6101 dissimilar aluminum alloys. Few researchers have shown the effect of a limited level quantity of process control parameters on the FS welding of the above-mentioned aluminum alloy combination. Literature review reveals that almost all the work at a time varying one control parameter and performed weld by the researchers and no consideration was given to the effect of two or more parameters on interaction. In this study, the dissimilar aluminum alloy AA7075-T6 and AA6101 of 6 mm thick plates were welded by friction stir welding the following process parameters tool rotation speed (1000 rpm, 1100 rpm, 1200 rpm), axial force (4 kN, 5 kN, 6 kN), welding speed (30 mm/min, 45 mm/min, 60 mm/min) with help of four different tool pin profile shown in Fig. 2 made up of mild steel and the pin portion flame hardened. 2. Materials and methods The materials utilized for this examination are aluminum groups AA7075 and AA6101. With the help of a power hacksaw machine the rolled plates of 6 mm in thickness were sliced into the essential size (100 mm 50 mm 6 mm) and squaring the butting faces with the help of the milling process. Before the FS welding process butting edges of the weld specimens were cleaned by using a wire brush. Weld edges to be welded were additionally arranged with the goals that are completely parallel to one another. This is to ensure that between the plates there is no uneven hole that may not give good properties welded joints. In addition, surface arrangement was also performed in such a way that the surfaces of both plates are of equivalent size and balance. The compound structure in terms of weight rate tabulated in Table 1 and Mechanical properties of the base metals employed in this investigation at atmospheric condition is recorded in Table 2.
Fig. 2. FS welding Tool shapes.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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G. Swaminathan, S. Sathiyamurthy / Materials Today: Proceedings xxx (xxxx) xxx Table 1 Chemical Compounds (wt %) of parent metals. Element
Al
Si
Fe
Cu
Mg
Mn
Zn
Ti
Cr
AA6101 AA7075
95 87.5
0.8 0.4
0.7 0.5
0.4 2.0
1.2 2.9
0.15 0.3
0.25 6.1
0.15 0.2
0.35 0.28
Table 2 Mechanical behaviors of parent metals. Element
UTS (MPa)
YS (MPa)
% of Elongation
Hardness
AA6101 AA7075
135 622
118 573
19 10
70 195
Traditional procedures for investigational design are too elaborate and difficult to apply in complicate experiments. ‘‘Once the no of operation control variables are more simultaneously more no of trials must be performed”. Taguchi’s technique was used to design the no of trials. L9 orthogonal array has been selected for three parameters and three levels. The parameter levels were selected from Table 3 and conduct the experiments. To perform the welding process, a vertical milling machine is act as a friction stir welding machine. Both plates are clamped into the fixture equipped by the manufacture of the FS welding joint by means of mechanical fixtures so that the weld plates are not separated at the time of welding operation. Both grade aluminum plates of size 100 mm 50 mm 6 mm were perfectly clamped in the FS welding machine, work table with back up plate shown in Fig. 3. In the downward direction, the tool is penetrated into butting edges of the plate. Due to higher frictional heating, higher tool rotation generates temperature and the results are more intense mixing of the material. The stir zone temperature was measured it by thermo-couple and data logger. Thermocouple is inserted top of backing plate. Make a hole in the backing plate to take out the thermocouple and connect it with data accusation system and measure the temperature near weld zone. By adding additional the thermocouple between tool pin-workpiece interfaces to gain better insight into the temperature distribution in the weld zone. The tensile behavior of FS welded joints was determined using the UTM (Make: FIE & Model: UTN 40). Tension testing provided information on material strength and ductility under uniaxial tensile stress. Under certain circumstances, this information can be useful in comparing materials, alloy development, quality control, and design. The trail samples were sliced from the fabricated joints and according to ASTM E8 standard. Three identical specimens were tested to acquire the average tensile strength value. The graphic image of the FS welded joint specimens after tensile fracture is exposed in Fig. 4. This test method cover the tension testing of metallic materials at ambient temperature in any form, primarily
Table 3 Process control variables. Sl. No
TRS (rpm)
AF (kN)
WS (mm/min)
1 2 3 4 5 6 7 8 9
1000 1000 1000 1100 1100 1100 1200 1200 1200
4 5 6 4 5 6 4 5 6
30 45 60 45 60 30 60 30 45
Fig. 3. Photographic views of clamped specimen.
Fig. 4. Tensile Test specimens after rupture.
the methods used to calculate yield strength, tensile strength, percentage of extensible and decrease in area. 3. Results and discussions 3.1. Effect of process control variables on tensile strength of the joints Frictional heat produced among the tool shove and the top face of the flat plate to be joined depends on the friction coefficient that the axial force determines. The production of sound joints requires adequate frictional heat associated with adequate squeezing of mellowed substance. Less heat produced at (lower) 4 kN AF as well as caused the inappropriate combination of material also found micro cavities which lead to pitiable tensile strength. The revolution of the tool produces frictional heat, exhilarating and combination of material in the region of the tool pin. To produce superior property joints with fine re-crystallized grains, appropriate exhilarating and sufficient heat creation is mandatory. Lower heat generated prevails at 1100 rpm TRS. This is also linked to a lack of stirring. Extreme TRS direct to elevated heat creation
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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Table 4 Domination of process control variables on tensile strength of Joints. Tool Rotational Speed (rpm)
Axial Force (KN)
Welding Speed (mm/min)
Tensile Strength (Mpa)
1000 1000 1000 1100 1100 1100 1200 1200 1200
4 5 6 4 5 6 4 5 6
30 45 60 45 60 30 60 30 45
Straight Tool
Taper Tool
Triangle Tool
Square Tool
116.13 120.18 127.29 125.37 122.93 116.81 128.5 120.87 124.87
111.93 119.68 118.28 111.93 114.1 114.67 113.92 112.57 116.78
120.35 122.73 123.22 132.42 131.2 124.68 126.87 124.24 128.42
114.35 121.31 118.72 121.78 124.26 120.29 117.23 119.54 122.98
Table 5 Optimum Tensile Strength of Joints. TRS (rpm)
AF (kN)
WS (mm/min)
Tool pin Profile
Tensile Strength (MPa)
1200 1000 1000 1100
4 5 4 5
60 45 45 60
St.Cyd. Tool Tp.Cyd.Tool Tri. Tool Sqr. Tool
128.5 119.68 132.42 124.26
Fig. 5. Domination of process control variables on Tensile Strength.
Fig. 6. Optimum Tensile Strength of Joints.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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G. Swaminathan, S. Sathiyamurthy / Materials Today: Proceedings xxx (xxxx) xxx Table 6 Domination of process control variables on % of Elongation. Tool Rotational Speed (rpm)
Axial Force (KN)
Welding Speed (mm/min)
Elongation %
1000 1000 1000 1100 1100 1100 1200 1200 1200
4 5 6 4 5 6 4 5 6
30 45 60 45 60 30 60 30 45
Table 7 Domination of operating variables on rate of elongation. TRS (rpm)
AF (kN)
WS (mm/min)
Tool Profile
Elongation (%)
1100 1000 1200 1200
6 4 5 6
30 30 30 45
SCT TCT TT ST
15.34 18.00 15.78 14.72
than demand and undue agitated materials are released. Too much exhilarating of materials roots the plasticized materials to stream irregularly. Ultra fine cavities come into sight at a TRS of
Straight Tool
Taper Tool
Triangle Tool
Square Tool
13.65 14.2 14 15 11.46 15.34 17 14 16
18 16.28 13.68 13.97 15.21 11.75 15.25 14.68 17.34
11.28 13.62 12.42 13.85 11.46 12.54 12.42 15.78 12.62
10.68 12.08 11 13.12 11.43 14.28 11.42 13.76 14.72
1200 rpm. The weld velocity causes the tool to be translated, which in twist squeezes the agitated material from the forefront to the rear of the tool pin and accomplished the welding. The chafing with the joint plate’s shoulder of the tool and pin produces frictional heat. The WS governs the disclosure time of this frictional heat per unit weld length and results in good material consolidation with fine grain. The effect of various tool pin shape on tensile strength tabulated in Tables 4 & 5 the maximum value of tensile strength obtained shown is bold in Table 5 and graphical representation of tensile strength verse tool profile are exhibited in Figs. 5 & 6. The maximum tensile strength of 132.42 MPa was observed at TRS of 1000 rpm, AF of 4 kN and WS of 45 mm/min. For the dissim-
Fig. 7. Domination of process control variables on % of Elongation.
Fig. 8. Optimum % of Elongation of Joints.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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ilar aluminum alloys AA7075-AA6101, employing a triangular tool profile imparts extreme tensile strength than to other tool profiles. The triangular tool pin profile generates extensive exciting effects between plates and tool simultaneously both materials mixed exhaustively and fine grains were formed. This is the causes was obtained superior tensile strength at this state. 3.2. Effect of process control variables on % elongation of the joints The dissimilar aluminum alloys AA7075-AA6101, employing a Triangular tool profile gave a higher percentage of elongation than to other tool shapes. The triangular tool pin shapes dynamite large
pulsating effects which cause superior tensile properties and also fine grains were formed. This is because of enough frictional and plastic flow of material. The consequence of various tool pin shape on rate of expansion tabulated in Tables 6 & 7 the maximum value of expansion obtained shown is bold in Table 7 and graphical representation of the percentage of elongation verse tool profile is shown in Figs. 7 & 8. The maximum percentage of elongation 15.78% was noted at TRS of 1200 rpm, AF of 5 kN and WS of 30 mm/min. The revolution of the tool produces frictional heat, exhilarating and combination of material in the region of the tool pin. To produce superior property joints with fine re-crystallized grains, appropriate exhilarating and sufficient heat creation is
Fig. 9. Weld nugget zone microstructure of significant tensile strength obtained Specimens.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
G. Swaminathan, S. Sathiyamurthy / Materials Today: Proceedings xxx (xxxx) xxx
mandatory. Lower heat generated prevails at 1100 rpm TRS. This is also linked to a lack of stirring. Extreme TRS direct to elevated heat creation than demand and undue agitated materials are released. Too much exhilarating of materials roots the plasticized materials to stream irregularly. Ultra fine cavities come into sight at a TRS of 1200 rpm.
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3.3. Weld zone microstructure of significant tensile strength obtained specimens The microstructure images show typical grain structures of stir zone in FS welded AA7075/AA6101 with various operation control parameters exposed in Fig. 9. The Nugget Zone incorporates of
Fig. 10. Weld nugget zone microstructure of significant % of elongation obtained Specimens.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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magnificent equiaxed grains due to dynamic re-crystallization and the grains in NZ are much smaller than those in other regions. The experimental results also reveal that the microstructure exists of refined grains and intermetallic particles of Fe3SiAl12 and Mg2Si. It is observed that the fusion region incorporate fine grains with more concentration intermetallic compositions which are consistently scattered. This is mainly due to cooling rate, as it diminishes with the increasing of heat contribution. From Fig. 9 (e) the utmost tensile strength was found at TRS of 1100 rpm, WS of 45 mm/min using the triangular tool profile. It clearly showed very fine grains evenly distributed throughout the nugget zone. Similarly from Fig. 9 (h) very less tensile strength was observed at TRS of 1100 rpm, Ws of 45 mm/min when employ the taper
Fig. 11. Photographic views of (SCT-Maximum Tensile Strength).
AA7075/AA6101
Tensile
tested
specimen
Fig. 12. Photographic views of (TCT-Maximum Tensile Strength).
AA7075/AA6101
Tensile
tested
specimen
circular tool pin shape. This may happen due to overheat and flushing. Also the onion rings were found in the weld zone, all magnesium precipitates found streamed like rivers, this also is one of the reasons for obtaining low mechanical properties.
3.4. Weld zone microstructure of significant % of elongation obtained specimens Results recorded that there was a crucial influence of FSW process variables on % elongation of each joint. Elongation increased with the increasing TRS up to 1200 rpm–6 kN, and then it decreased with decreasing TRS, and AF to 1000 rpm–4 kN, due to
Fig. 13. Photographic views of (TT-Maximum Tensile Strength).
AA7075/AA6101
Tensile
tested
specimen
Fig. 14. Photographic views of (ST-Maximum Tensile Strength).
AA7075/AA6101
Tensile
tested
specimen
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
G. Swaminathan, S. Sathiyamurthy / Materials Today: Proceedings xxx (xxxx) xxx
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in Fig. 13 (b) an identical irregular surfaces can be perceived. In the fractured area image shown in Fig. 13 (c) there are extra fine dents facets and deformed edges noticed which is the root of ductile crash, which resulted obtain utmost tensile strength. The plate was welded with the help of a square tool at 1200 rpm TRS, WS of 30 mm/min and 5 kN AF. During the axial tensile test utmost tensile strength of 124.6 MPa was noted and all the samples fractured in the heat afflicted zone of soft metal AA6063 side due to low hardness. Fig. 14 (a) shows the fracture specimen picture. From the macroscopic observation of the ruptured surface showed in Fig. 14 (b) a consistent irregular surfaces can be recorded. The fractured surface image shown in Fig. 14 (c) there are more course dimples facets and deformed thick edges noticed which the origin of yield failure is and provide the elevated tensile strength. 3.6. Effect of inter-metallic’s on mechanical properties
Fig. 15. X-RAY Diffraction pattern of AA7075/AA6101 weld zone.
high heat generation grain growth which means increase in size of grains hence more elongation. Circumstance of 1200 rpm, 6 kN and circular taper profile tool achieved the maximum elongation value of 18%, while the minimum value 10.68% was at 1000 rpm, 4 kN and square tool profile. The axial force does not disturb the elongation of the welded joints. The percent of elongation for each joint is shown in Fig. 10 (a-h). 3.5. Fracture behaviors of tensile tested specimens SEM investigation was conducted on the tensile test specimen’s ruptured surface of the FSW joints. In order to perceive the microstructure alteration in the broken area of the FS welded aluminum alloy AA7075/AA6101, the SEM representation was captured at 200 lm for maximum and minimum tensile strength stage. The joint was made-up with the help of a straight cylindrical tool at 1200 rpm TRS, WS of 60 mm/min and 4 kN AF. During the tensile test utmost tensile strength of 128.50 MPa was found and almost all the samples fractured in the heat afflicted region of AA6101 side due to low hardness. Fig. 11 (a) shows the fracture specimen photograph. The macroscopic observation of the rupture surface showed in Fig. 11 (b) a regular rough surface can be perceived. The fractured area image is shown in Fig. 11 (c) there are more fine dents facade and deformed edges diagnosed which is the root for extensile breakdown, which resulted in utmost tensile strength. The plate was welded with the help of a taper cylindrical tool at 1000 rpm TRS, WS of 45 mm/min and 5 kN AF. During the axial load test utmost tensile strength of 119.68 MPa was recorded and all the test samples failed in the heat afflicted region of advancing side of weld due to low hardness. Fig. 12 (a) shows the break sample photograph. From the macroscopic view of the rupture face showed in Fig. 12 (b) a uniform rough surfaces can be observed. The fractured surface appearance showed in Fig. 12 (c) there are more fine dimples facets and few deformed edges noted, which is the origin of ductile rupture, resulted obtain moderate tensile strength. The joint was prepared with the help of a triangular tool at 1000 rpm tool revolving speed, welding peed of 30 mm/min and 5 kN axial forces. During the axial tensile test utmost tensile strength of 132.42 MPa was recorded and almost all the test samples ruptured in the heat afflicted region of the soft metal AA6063 side due to low hardness. Fig. 13 (a) shows the fracture specimen picture. From the macroscopic view of the fracture surface showed
The existence of intermetallic compounds in Al alloys is of a great concern to materials engineers due to their harmful effects on mechanical properties. Mechanical behaviors of Al-Si- alloys are significantly influenced by the structures of the intermetallic. Intermetallics compounds appear more in recycled Al-Si based alloys, however, cycling which is a secondary production process of Al and its alloys is cheaper than primary production process. Therefore, producing Al alloys devoid of deleterious intermetallic phases will positively affect Al and its alloys recycle market and decrease the use of primary method that requires high fabrication power consumption. The b-phase platelets are usually potential sites for crack initiation, where eventual breakup failure occurs. Iron-based intermetallics dominate Al-Si-X alloys’ intermetallics studies. Commercially available alloys contain Fe impurities in the form of Al and Si and other elements phases shown in Fig. 15. In conductive liquids, the presence of certain Fe-phases, Al3 Fe and a-AlFeSi, on the surface stimulates pitting attacks on the surface because a-AlFeSi is cathodic in the Al matrix. The greatest disadvantage of intermetallics is their low ductility, especially at low and transitional temperatures. 4. Conclusions The utmost tensile strength of 132.42 MPa was observed at TRS of 1000 rpm, AF of 4 kN and WS of 45 mm/min. For the dissimilar aluminum alloys AA7075-AA6101, employing a triangular tool profile imparts higher tensile strength than to other tool profiles. The triangular tool pin profile generates extensive exciting effects between both plates with the tool. Simultaneously both materials were mixed exhaustively and fine grains formed. These are the causes for obtaining superior tensile strength in this state. The maximum percentage of elongation 15.78% was noted at TRS of 1200 rpm, AF of 5 kN and WS of 30 mm/min. The triangular tool pin profile produces large pulsating effects which cause superior tensile properties that also formed fine grains. This is because of enough frictional and plastic flow of material which forms fine grains microstructure in the weld zone. The above results conclude that Triangular tool profile is suitable for joining AA7075/AA6101 for better mechanical and material properties. References [1] W.M. Thomas, E.D. Nichols, J.C. Needam, M.G. Murch, P. Temple Smith, C.J. Dawes. GB Patent Application No:9125978.8, December 1991 and US patent No:5460317, October 1995. [2] R.S. Mishra, Z.Y. Mab, Friction stir welding and processing, Mater. Sci. Eng. R50 (2005) 1–78.
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Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys G. Swaminathan a,⇑, S. Sathiyamurthy b a b
Assistant professor, Department of Mechanical Engineering, SRMIST, Chennai 89, India Professor, Department of Automobile Engineering, Easwari Engineering College, Chennai 89, India
a r t i c l e
i n f o
Article history: Received 10 June 2019 Received in revised form 11 September 2019 Accepted 13 September 2019 Available online xxxx Keywords: Light-weight Process control variables Tensile properties Tool profile Microstructure Rupture behaviors
a b s t r a c t In this work, flaw free joints of AA7075 and AA6101 alloy 6 mm of plate’s thickness were butt jointed using FS welding. The FS welding has been done at various combinations of process parameters. The quality of the joints is influenced by process variables like tool rotational speed, axial force, welding speed and tool profile. The effect of these variables on tensile properties, microstructure structure and rupture behavior of the welded joints are discussed. Tool revolving speed and tool profile play key control on tensile properties and obtain the extensive requirements in the field of light-weight building construction. Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Materials Engineering and Characterization 2019.
1. Introduction The need for greater energy efficiency in today’s LEED (Leadership in Energy and Environmental Design) certified buildings are fueling the use of sustainable, corrosion-resistant materials from floor to ceiling. In commercial and residential buildings, we offer higher-strength specialty material solutions that can reduce overall project lifecycle costs. Friction stir welding offers the likelihood to deliver superior properties joints with short process durations and no extra joining components like filler rod, strap plates, etc., Main benefit of FS welding is that it permits to joining of non-ferrous alloys like aluminum alloys, copper alloys etc., that are considered to be not fusion weldable and of dissimilar material combinations. The quality of a FS welded joint depends on the process control variables of welding conditions, but is weaker than both the base materials. In Friction stir welding process a non consumable tool is to be plunged into the butt surface of the plates with rotation and also it moves along the butting line for weld consolidation and the schematic diagram of friction stir welding as shown in Fig. 1 The tool pin and shoulder are useful for heat generation and blending of materials by stirring and generating the
⇑ Corresponding author. E-mail address: [email protected] (G. Swaminathan).
joint. No melting happens in this phase and the heat generation takes place internally through friction between the material-tool interface and plastic deformation [1]. No cover gas of flux is used in friction stir welding, making the method eco-friendly, energy efficient and green technology. The joining does not require any use of filler metal and therefore any aluminum alloy can be joined without worrying about masterpiece compatibility, which is a problem in fusion welding [2]. In FSW parameters such as tool shape, material, tool rotational velocity, welding velocity and axial force are required to produce efficient friction stir welded joint and achieve a joint effectiveness of 60% [3]. Using different process parameters, joints are acquired in FSW. An ANN model is created using MATLAB and process parameter optimization is performed by comparing the results acquired by designing tests and experimental values of multiple tool pin profiles with distinct process parameters of welding performed on distinct components AA6061, AA6351 and AA6082 [4]. A systematic strategy to the development of the mathematical model to predict the ultimate strength, yield strength and proportion of AA6351 elongation commonly used in industry. The rise in rotational velocity, welding velocity and axial force led to an rise in the ultimate strength and its peak value and then decreased [5]. Effect of FSW process parameters on welded AA6061 aluminum alloy mechanical characteristics. It was found that the tensile strength initially increased with the increase in tool rotational
https://doi.org/10.1016/j.matpr.2019.09.034 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Materials Engineering and Characterization 2019.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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G. Swaminathan, S. Sathiyamurthy / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 1. Schematic Diagram of Friction Stir Welding (Courtesy: S. Sattari [14]).
speed, welding speed and axial force, but the tensile strength decreased after the maximum value was achieved with the further increase of these parameters [6]. Friction stir welding of very thin AA6016-T4 aluminum alloy plates, it was found that the distinction in instrument geometry and welding parameters included significant adjustments in the material flow route during welding as well as in the welding nugget microstructure [7]. Using 33 complete factorial experiment design, the tensile resistance of FSW aluminum alloy A319 was assessed under distinct handling circumstances. Dominant parameter for tensile strength was discovered for tool rotation velocity followed by welded velocity, axial force indicates minimal impact on tensile strength compared to other parameters. A nonlinear regression model that was established to correlate tensile strength was discovered to be helpful in predicting tensile strength [8]. To create the joints, five separate tool pin profiles were used with 3 distinct welding speeds. The straight pin profile with 63 mm/min was discovered to produce better tensile strength than other profile and welding velocity [9]. The FSW of the dissimilar aluminum alloy test was conducted using the cylindrical tool profile and the joint test and the outcome was compared with the base metals [10]. Compare the mechanical and metallurgical characteristics of the welded joints TIG, MIG and Friction dissimilar aluminum alloy AA5083-0 and AA6061-T6 affected by the parameters of the welding method and the
treatment of post-welding aging. Compared to MIG and TIG welded joints, FSW joints are welded. The FSW method therefore displayed superior mechanical and metallurgical characteristics [11–13]. The mechanical characteristics of the Dissimilar Friction stir welded samples have been evaluated and contrasted by optical microscopy with the parent’s base materials and microstructures and a welded specimen, and the welding parameters have a major impact on the mechanical and metallurgical characteristics of the weld [14–17]. Based on the above literature survey, there were a number of discrepancies in friction stir welding of AA7075/AA6101 dissimilar aluminum alloys. Few researchers have shown the effect of a limited level quantity of process control parameters on the FS welding of the above-mentioned aluminum alloy combination. Literature review reveals that almost all the work at a time varying one control parameter and performed weld by the researchers and no consideration was given to the effect of two or more parameters on interaction. In this study, the dissimilar aluminum alloy AA7075-T6 and AA6101 of 6 mm thick plates were welded by friction stir welding the following process parameters tool rotation speed (1000 rpm, 1100 rpm, 1200 rpm), axial force (4 kN, 5 kN, 6 kN), welding speed (30 mm/min, 45 mm/min, 60 mm/min) with help of four different tool pin profile shown in Fig. 2 made up of mild steel and the pin portion flame hardened. 2. Materials and methods The materials utilized for this examination are aluminum groups AA7075 and AA6101. With the help of a power hacksaw machine the rolled plates of 6 mm in thickness were sliced into the essential size (100 mm 50 mm 6 mm) and squaring the butting faces with the help of the milling process. Before the FS welding process butting edges of the weld specimens were cleaned by using a wire brush. Weld edges to be welded were additionally arranged with the goals that are completely parallel to one another. This is to ensure that between the plates there is no uneven hole that may not give good properties welded joints. In addition, surface arrangement was also performed in such a way that the surfaces of both plates are of equivalent size and balance. The compound structure in terms of weight rate tabulated in Table 1 and Mechanical properties of the base metals employed in this investigation at atmospheric condition is recorded in Table 2.
Fig. 2. FS welding Tool shapes.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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G. Swaminathan, S. Sathiyamurthy / Materials Today: Proceedings xxx (xxxx) xxx Table 1 Chemical Compounds (wt %) of parent metals. Element
Al
Si
Fe
Cu
Mg
Mn
Zn
Ti
Cr
AA6101 AA7075
95 87.5
0.8 0.4
0.7 0.5
0.4 2.0
1.2 2.9
0.15 0.3
0.25 6.1
0.15 0.2
0.35 0.28
Table 2 Mechanical behaviors of parent metals. Element
UTS (MPa)
YS (MPa)
% of Elongation
Hardness
AA6101 AA7075
135 622
118 573
19 10
70 195
Traditional procedures for investigational design are too elaborate and difficult to apply in complicate experiments. ‘‘Once the no of operation control variables are more simultaneously more no of trials must be performed”. Taguchi’s technique was used to design the no of trials. L9 orthogonal array has been selected for three parameters and three levels. The parameter levels were selected from Table 3 and conduct the experiments. To perform the welding process, a vertical milling machine is act as a friction stir welding machine. Both plates are clamped into the fixture equipped by the manufacture of the FS welding joint by means of mechanical fixtures so that the weld plates are not separated at the time of welding operation. Both grade aluminum plates of size 100 mm 50 mm 6 mm were perfectly clamped in the FS welding machine, work table with back up plate shown in Fig. 3. In the downward direction, the tool is penetrated into butting edges of the plate. Due to higher frictional heating, higher tool rotation generates temperature and the results are more intense mixing of the material. The stir zone temperature was measured it by thermo-couple and data logger. Thermocouple is inserted top of backing plate. Make a hole in the backing plate to take out the thermocouple and connect it with data accusation system and measure the temperature near weld zone. By adding additional the thermocouple between tool pin-workpiece interfaces to gain better insight into the temperature distribution in the weld zone. The tensile behavior of FS welded joints was determined using the UTM (Make: FIE & Model: UTN 40). Tension testing provided information on material strength and ductility under uniaxial tensile stress. Under certain circumstances, this information can be useful in comparing materials, alloy development, quality control, and design. The trail samples were sliced from the fabricated joints and according to ASTM E8 standard. Three identical specimens were tested to acquire the average tensile strength value. The graphic image of the FS welded joint specimens after tensile fracture is exposed in Fig. 4. This test method cover the tension testing of metallic materials at ambient temperature in any form, primarily
Table 3 Process control variables. Sl. No
TRS (rpm)
AF (kN)
WS (mm/min)
1 2 3 4 5 6 7 8 9
1000 1000 1000 1100 1100 1100 1200 1200 1200
4 5 6 4 5 6 4 5 6
30 45 60 45 60 30 60 30 45
Fig. 3. Photographic views of clamped specimen.
Fig. 4. Tensile Test specimens after rupture.
the methods used to calculate yield strength, tensile strength, percentage of extensible and decrease in area. 3. Results and discussions 3.1. Effect of process control variables on tensile strength of the joints Frictional heat produced among the tool shove and the top face of the flat plate to be joined depends on the friction coefficient that the axial force determines. The production of sound joints requires adequate frictional heat associated with adequate squeezing of mellowed substance. Less heat produced at (lower) 4 kN AF as well as caused the inappropriate combination of material also found micro cavities which lead to pitiable tensile strength. The revolution of the tool produces frictional heat, exhilarating and combination of material in the region of the tool pin. To produce superior property joints with fine re-crystallized grains, appropriate exhilarating and sufficient heat creation is mandatory. Lower heat generated prevails at 1100 rpm TRS. This is also linked to a lack of stirring. Extreme TRS direct to elevated heat creation
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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Table 4 Domination of process control variables on tensile strength of Joints. Tool Rotational Speed (rpm)
Axial Force (KN)
Welding Speed (mm/min)
Tensile Strength (Mpa)
1000 1000 1000 1100 1100 1100 1200 1200 1200
4 5 6 4 5 6 4 5 6
30 45 60 45 60 30 60 30 45
Straight Tool
Taper Tool
Triangle Tool
Square Tool
116.13 120.18 127.29 125.37 122.93 116.81 128.5 120.87 124.87
111.93 119.68 118.28 111.93 114.1 114.67 113.92 112.57 116.78
120.35 122.73 123.22 132.42 131.2 124.68 126.87 124.24 128.42
114.35 121.31 118.72 121.78 124.26 120.29 117.23 119.54 122.98
Table 5 Optimum Tensile Strength of Joints. TRS (rpm)
AF (kN)
WS (mm/min)
Tool pin Profile
Tensile Strength (MPa)
1200 1000 1000 1100
4 5 4 5
60 45 45 60
St.Cyd. Tool Tp.Cyd.Tool Tri. Tool Sqr. Tool
128.5 119.68 132.42 124.26
Fig. 5. Domination of process control variables on Tensile Strength.
Fig. 6. Optimum Tensile Strength of Joints.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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G. Swaminathan, S. Sathiyamurthy / Materials Today: Proceedings xxx (xxxx) xxx Table 6 Domination of process control variables on % of Elongation. Tool Rotational Speed (rpm)
Axial Force (KN)
Welding Speed (mm/min)
Elongation %
1000 1000 1000 1100 1100 1100 1200 1200 1200
4 5 6 4 5 6 4 5 6
30 45 60 45 60 30 60 30 45
Table 7 Domination of operating variables on rate of elongation. TRS (rpm)
AF (kN)
WS (mm/min)
Tool Profile
Elongation (%)
1100 1000 1200 1200
6 4 5 6
30 30 30 45
SCT TCT TT ST
15.34 18.00 15.78 14.72
than demand and undue agitated materials are released. Too much exhilarating of materials roots the plasticized materials to stream irregularly. Ultra fine cavities come into sight at a TRS of
Straight Tool
Taper Tool
Triangle Tool
Square Tool
13.65 14.2 14 15 11.46 15.34 17 14 16
18 16.28 13.68 13.97 15.21 11.75 15.25 14.68 17.34
11.28 13.62 12.42 13.85 11.46 12.54 12.42 15.78 12.62
10.68 12.08 11 13.12 11.43 14.28 11.42 13.76 14.72
1200 rpm. The weld velocity causes the tool to be translated, which in twist squeezes the agitated material from the forefront to the rear of the tool pin and accomplished the welding. The chafing with the joint plate’s shoulder of the tool and pin produces frictional heat. The WS governs the disclosure time of this frictional heat per unit weld length and results in good material consolidation with fine grain. The effect of various tool pin shape on tensile strength tabulated in Tables 4 & 5 the maximum value of tensile strength obtained shown is bold in Table 5 and graphical representation of tensile strength verse tool profile are exhibited in Figs. 5 & 6. The maximum tensile strength of 132.42 MPa was observed at TRS of 1000 rpm, AF of 4 kN and WS of 45 mm/min. For the dissim-
Fig. 7. Domination of process control variables on % of Elongation.
Fig. 8. Optimum % of Elongation of Joints.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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ilar aluminum alloys AA7075-AA6101, employing a triangular tool profile imparts extreme tensile strength than to other tool profiles. The triangular tool pin profile generates extensive exciting effects between plates and tool simultaneously both materials mixed exhaustively and fine grains were formed. This is the causes was obtained superior tensile strength at this state. 3.2. Effect of process control variables on % elongation of the joints The dissimilar aluminum alloys AA7075-AA6101, employing a Triangular tool profile gave a higher percentage of elongation than to other tool shapes. The triangular tool pin shapes dynamite large
pulsating effects which cause superior tensile properties and also fine grains were formed. This is because of enough frictional and plastic flow of material. The consequence of various tool pin shape on rate of expansion tabulated in Tables 6 & 7 the maximum value of expansion obtained shown is bold in Table 7 and graphical representation of the percentage of elongation verse tool profile is shown in Figs. 7 & 8. The maximum percentage of elongation 15.78% was noted at TRS of 1200 rpm, AF of 5 kN and WS of 30 mm/min. The revolution of the tool produces frictional heat, exhilarating and combination of material in the region of the tool pin. To produce superior property joints with fine re-crystallized grains, appropriate exhilarating and sufficient heat creation is
Fig. 9. Weld nugget zone microstructure of significant tensile strength obtained Specimens.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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mandatory. Lower heat generated prevails at 1100 rpm TRS. This is also linked to a lack of stirring. Extreme TRS direct to elevated heat creation than demand and undue agitated materials are released. Too much exhilarating of materials roots the plasticized materials to stream irregularly. Ultra fine cavities come into sight at a TRS of 1200 rpm.
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3.3. Weld zone microstructure of significant tensile strength obtained specimens The microstructure images show typical grain structures of stir zone in FS welded AA7075/AA6101 with various operation control parameters exposed in Fig. 9. The Nugget Zone incorporates of
Fig. 10. Weld nugget zone microstructure of significant % of elongation obtained Specimens.
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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magnificent equiaxed grains due to dynamic re-crystallization and the grains in NZ are much smaller than those in other regions. The experimental results also reveal that the microstructure exists of refined grains and intermetallic particles of Fe3SiAl12 and Mg2Si. It is observed that the fusion region incorporate fine grains with more concentration intermetallic compositions which are consistently scattered. This is mainly due to cooling rate, as it diminishes with the increasing of heat contribution. From Fig. 9 (e) the utmost tensile strength was found at TRS of 1100 rpm, WS of 45 mm/min using the triangular tool profile. It clearly showed very fine grains evenly distributed throughout the nugget zone. Similarly from Fig. 9 (h) very less tensile strength was observed at TRS of 1100 rpm, Ws of 45 mm/min when employ the taper
Fig. 11. Photographic views of (SCT-Maximum Tensile Strength).
AA7075/AA6101
Tensile
tested
specimen
Fig. 12. Photographic views of (TCT-Maximum Tensile Strength).
AA7075/AA6101
Tensile
tested
specimen
circular tool pin shape. This may happen due to overheat and flushing. Also the onion rings were found in the weld zone, all magnesium precipitates found streamed like rivers, this also is one of the reasons for obtaining low mechanical properties.
3.4. Weld zone microstructure of significant % of elongation obtained specimens Results recorded that there was a crucial influence of FSW process variables on % elongation of each joint. Elongation increased with the increasing TRS up to 1200 rpm–6 kN, and then it decreased with decreasing TRS, and AF to 1000 rpm–4 kN, due to
Fig. 13. Photographic views of (TT-Maximum Tensile Strength).
AA7075/AA6101
Tensile
tested
specimen
Fig. 14. Photographic views of (ST-Maximum Tensile Strength).
AA7075/AA6101
Tensile
tested
specimen
Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034
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in Fig. 13 (b) an identical irregular surfaces can be perceived. In the fractured area image shown in Fig. 13 (c) there are extra fine dents facets and deformed edges noticed which is the root of ductile crash, which resulted obtain utmost tensile strength. The plate was welded with the help of a square tool at 1200 rpm TRS, WS of 30 mm/min and 5 kN AF. During the axial tensile test utmost tensile strength of 124.6 MPa was noted and all the samples fractured in the heat afflicted zone of soft metal AA6063 side due to low hardness. Fig. 14 (a) shows the fracture specimen picture. From the macroscopic observation of the ruptured surface showed in Fig. 14 (b) a consistent irregular surfaces can be recorded. The fractured surface image shown in Fig. 14 (c) there are more course dimples facets and deformed thick edges noticed which the origin of yield failure is and provide the elevated tensile strength. 3.6. Effect of inter-metallic’s on mechanical properties
Fig. 15. X-RAY Diffraction pattern of AA7075/AA6101 weld zone.
high heat generation grain growth which means increase in size of grains hence more elongation. Circumstance of 1200 rpm, 6 kN and circular taper profile tool achieved the maximum elongation value of 18%, while the minimum value 10.68% was at 1000 rpm, 4 kN and square tool profile. The axial force does not disturb the elongation of the welded joints. The percent of elongation for each joint is shown in Fig. 10 (a-h). 3.5. Fracture behaviors of tensile tested specimens SEM investigation was conducted on the tensile test specimen’s ruptured surface of the FSW joints. In order to perceive the microstructure alteration in the broken area of the FS welded aluminum alloy AA7075/AA6101, the SEM representation was captured at 200 lm for maximum and minimum tensile strength stage. The joint was made-up with the help of a straight cylindrical tool at 1200 rpm TRS, WS of 60 mm/min and 4 kN AF. During the tensile test utmost tensile strength of 128.50 MPa was found and almost all the samples fractured in the heat afflicted region of AA6101 side due to low hardness. Fig. 11 (a) shows the fracture specimen photograph. The macroscopic observation of the rupture surface showed in Fig. 11 (b) a regular rough surface can be perceived. The fractured area image is shown in Fig. 11 (c) there are more fine dents facade and deformed edges diagnosed which is the root for extensile breakdown, which resulted in utmost tensile strength. The plate was welded with the help of a taper cylindrical tool at 1000 rpm TRS, WS of 45 mm/min and 5 kN AF. During the axial load test utmost tensile strength of 119.68 MPa was recorded and all the test samples failed in the heat afflicted region of advancing side of weld due to low hardness. Fig. 12 (a) shows the break sample photograph. From the macroscopic view of the rupture face showed in Fig. 12 (b) a uniform rough surfaces can be observed. The fractured surface appearance showed in Fig. 12 (c) there are more fine dimples facets and few deformed edges noted, which is the origin of ductile rupture, resulted obtain moderate tensile strength. The joint was prepared with the help of a triangular tool at 1000 rpm tool revolving speed, welding peed of 30 mm/min and 5 kN axial forces. During the axial tensile test utmost tensile strength of 132.42 MPa was recorded and almost all the test samples ruptured in the heat afflicted region of the soft metal AA6063 side due to low hardness. Fig. 13 (a) shows the fracture specimen picture. From the macroscopic view of the fracture surface showed
The existence of intermetallic compounds in Al alloys is of a great concern to materials engineers due to their harmful effects on mechanical properties. Mechanical behaviors of Al-Si- alloys are significantly influenced by the structures of the intermetallic. Intermetallics compounds appear more in recycled Al-Si based alloys, however, cycling which is a secondary production process of Al and its alloys is cheaper than primary production process. Therefore, producing Al alloys devoid of deleterious intermetallic phases will positively affect Al and its alloys recycle market and decrease the use of primary method that requires high fabrication power consumption. The b-phase platelets are usually potential sites for crack initiation, where eventual breakup failure occurs. Iron-based intermetallics dominate Al-Si-X alloys’ intermetallics studies. Commercially available alloys contain Fe impurities in the form of Al and Si and other elements phases shown in Fig. 15. In conductive liquids, the presence of certain Fe-phases, Al3 Fe and a-AlFeSi, on the surface stimulates pitting attacks on the surface because a-AlFeSi is cathodic in the Al matrix. The greatest disadvantage of intermetallics is their low ductility, especially at low and transitional temperatures. 4. Conclusions The utmost tensile strength of 132.42 MPa was observed at TRS of 1000 rpm, AF of 4 kN and WS of 45 mm/min. For the dissimilar aluminum alloys AA7075-AA6101, employing a triangular tool profile imparts higher tensile strength than to other tool profiles. The triangular tool pin profile generates extensive exciting effects between both plates with the tool. Simultaneously both materials were mixed exhaustively and fine grains formed. These are the causes for obtaining superior tensile strength in this state. The maximum percentage of elongation 15.78% was noted at TRS of 1200 rpm, AF of 5 kN and WS of 30 mm/min. The triangular tool pin profile produces large pulsating effects which cause superior tensile properties that also formed fine grains. This is because of enough frictional and plastic flow of material which forms fine grains microstructure in the weld zone. The above results conclude that Triangular tool profile is suitable for joining AA7075/AA6101 for better mechanical and material properties. References [1] W.M. Thomas, E.D. Nichols, J.C. Needam, M.G. Murch, P. Temple Smith, C.J. Dawes. GB Patent Application No:9125978.8, December 1991 and US patent No:5460317, October 1995. [2] R.S. Mishra, Z.Y. Mab, Friction stir welding and processing, Mater. Sci. Eng. R50 (2005) 1–78.
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Please cite this article as: G. Swaminathan and S. Sathiyamurthy, Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.034