- Email: [email protected]
Failure analysis of the balance ball pin in the car steering system
Engineering Failure Analysis 94 (2018) 232–238
Contents lists available at ScienceDirect
Engineering Failure Analysis journal homepage: www.elsevier.com/locate/engfailanal
Failure analysis of the balance ball pin in the car steering system ⁎
Ruidong Guo, Song Xue , Ailin Deng
T
College of Manufacturing Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
A R T IC LE I N F O
ABS TRA CT
Keywords: Failure analysis Balance ball pin Microcracks Fatigue fracture
A balance ball pin used in the car steering system was found broken into two pieces. An evaluation of the failed part was investigated to determine the cause of failure and assess its integrity. Mechanical properties tests of the material are conducted first. Macroscopic examinations, scanning electronic microscopy(SEM) examination, metallographic examination,hardness measurement and chemical composition analysis were all conducted. The results indicated that fatigue fracture is the main fracture mode, and the uneven quench treatment led to the inhomogeneous thickness of quench-hardened case. As a result, in the fluctuations load, microcracks along the circumferential direction emerged on the subsurface of the quench-hardened case. Moreover, due to poor assembly, the stabilizer bar didn't turn smoothly in the working and fitting surface was worn badly, where produced the large resistance, which is the main torque to the ball pin.
1. Introduction With the wider application of steering system in cars, the reliability and stability of it make a difference in the driving safety. The steering equilibrium units, including balance ball pin, transverse stabilizer bar and link rod and so on, play a key role in the process of driving. The balance ball pin, which is widely used in the steering system, is the most important connector among the transverse stabilizer bar constituting the link rod [1]. The balance ball pin transmits force from the transverse stabilizer bar to link rod. In the processing of working, balance ball pin bounce up and down or turns, and its angle has a larger swing. Therefore, the balance ball pin is subjected to great shear stress and easy to damage, which occurs frequently in driving. The processing technology of the balance ball pin is already mature. However, failure occurs particularly due to the manufacturing errors and misuse in working. The general types of car steering system failure include fatigue failure, impact fracture, wear and stress rupture [2]. In addition, there are several other factors that influence failure which include poor assembly, material defects, processing technology, improper heat treatment and subsurface defects in critical areas. Fatigue is one of the most commons automotive components failures [3]. Due to rubbing and wearing, a large torque is generated in the process of working. If the balance ball rubbing and wearing is serious, it is necessary to replace it. The failed balance ball pin prevents the steering system from functioning properly and causes the critical issues in driving safety [4]. The manufacturer received nearly 10 reports about the balance ball pin early fracture in one year, in order to prevent the similar case, investigate the early fracture cause in the automobile steering system is very important. Seung K. Koh [5] investigated a fatigue failure analysis of an automotive link. The analysis indicated the steering link rod occurred low-cycle fatigue failure at the middle region and the fracture crack is initiated at the highly stressed region. The fracture is taken place after a fatigue procedure under a combined bending and torsional stresses. Wassim Maktouf et al. [6] presented a fracture
⁎
Corresponding author. E-mail address: [email protected] (S. Xue).
https://doi.org/10.1016/j.engfailanal.2018.08.015 Received 7 March 2018; Received in revised form 4 May 2018; Accepted 13 August 2018 Available online 15 August 2018 1350-6307/ © 2018 Elsevier Ltd. All rights reserved.
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 1. Fractured balance ball pin.
analysis of automobile anti-roll bar. They found that the fractured of anti-roll bar in a ductile manner, caused a combined bending and torsional stress. The above analysis and investigations provide the probable root failure causes of different parts of the steering system. This will provide guidance for the study of this article. The cracked balance ball pin is shown in Fig. 1. The global assembly relation of the transverse stabilizer bar, the link rod and the balance ball pin is shown in Fig. 2(a) and (b). A ball pin consists of a threaded part and a fitting part. The balance ball pin is mainly subject to fluctuations load. Failure took place in the middle part which is made of 40Cr steel with a diameter of 18 mm. And this material is a mature material, which is widely used in automotive connectors. After quenching on the ball pin surface, the surface has higher hardness [7]. This paper presents a failure analysis case on a balance ball pin in the car steering system. Based on the factors influencing the failure of a ball pin, some suggestions for preventing these kinds of failures are proposed for subsequent production of this kind of balance ball pin. 2. Equipment and procedures The chemical composition of balance ball pin was determined by Energy Dispersive Spectrometer(EDS) chemical analysis. The mechanical properties were conducted. Micro-hardness profiles from surface to interior in various regions were made. The fracture surface was observed by visual examination and scanning electronic microscopy (SEM). The microstructure was observed by optical metallography. 3. Results 3.1. Visual inspection Failed balance ball pin is shown in Fig. 3. Multiple parallel scratches existing on the outer surface indicated the balance ball pin was worn. The fracture surface character is shown in Fig. 4, which is covered with corrosion. Three different feature zones of the fracture surface are designated as initial zone, expansion zone and final fracture zone, respectively. The extend zone shows the fine fatigue striation, which is a typical characteristic of fatigue failure. The final fracture zone which is near the fracture edge appears the shear lips. 3.2. Micro-fracture examination The examination around the ball pin surface revealed that there are a lot of parallel cracks, shown in Fig. 5(a). A lot of debris can be seen under high magnification, shown in Fig. 5(b). EDS result of the cracks is shown in Fig. 6,which indicates that crack surface is covered with the principal elements O and Fe. With the above analysis, it can be identified that the parallel cracks belong to fatigue cracks, and the debris on the cracks is mainly composed of iron oxides. The micromorphology of initial area, which indicates that there is no obvious crack source, lots of cracks propagating along the circumference and the river pattern, shown in Fig. 7(a) and (b). The outer surface exists the dense and uneven quench-hardened case, shown in Fig.7(c). There are lots of irregular cracks on the subsurface where the fatigue source is located and the cracks initiate,
Fig. 2. Macroscopic assembly: (a) Global assembly; (b) Local assembly. 233
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 3. Macro morphology of surface: (a) The surface is worn; (b) Multiple parallel scratchs.
Fig. 4. Macro morphology of the two matched fractures: (a)Fracture surface ‘A’; (b) Fracture surface ‘B’
Fig. 5. Multiple parallel cracks in the surface distribution near the starting crack area: (a) parallel cracks; (b) debris in cracks.
shown in Fig.7(d). There are many dead wood cracks in the expansion zone, shown in Fig.8. The secondary cracks where the white lump inclusions distribute are perpendicular to the radial distribution, shown in Fig.8(a) and (b). Moreover, the irregular holes appear around the tip of cracks, shown in Fig.8(c). The micromorphology of the final fracture zone indicates that the fracture is smooth and has the clear shear lips, shown in Fig.9(a). Besides, there is the typical dimple morphology with ductile tearing shape, shown in Fig.9(b). 3.3. Metallography The metallography of the microstructure of balance ball pin based on experimental study is shown in Fig.10. The results reveal the material microstructure of failure balance ball pin consisting of homogeneous tempered sorbate +small amount of granular carbide, which are based on GB/T13320-2007 standard assessment for level 1. 234
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 6. EDS: (a)Micro morphology of cracks; (b) EDS analysis.
Fig. 7. Microstructure of cracks initial area: (a) the circumferential cracks (b) the river pattern (c) the quench-hardened case (d) microstructure of subsurface.
3.4. Mechanical properties Table 1 shows the chemical composition of the failed balance ball pin and the requirement on the compositions content of these kinds of balance ball pin. It displayed that the chemical compositions of the failed ring gear meet the standard requirement. Specimen for tensile was machined from the failed balance ball pin according to SY/T5561-2008 standard. Table 2 shows the testing results, which indicates that mechanical properties of balance ball pin meet SY/T5561-2008 standard requirements.
3.5. Hardness measurement Hardness measurement of the 1/2 radius of the balance ball pin and the surface of the balance ball pin were implemented to verify if manufacture process meets the requirements. The hardness of quench influence layer is required in the range of 45 HRC–52 HRC. The core hardness of balance ball pin is specified in the range of 32–36 HRC. The hardness of the 1/2 radius of the balance ball pin 235
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 8. Microstructure of extend zone 4: (a) dead wood cracks, (b) secondary cracks and inclusions, (c) the irregular holes.
Fig. 9. Microstructure of the final fracture zone: (a) shear lips (b) dimples.
and the surface of the balance ball pin were measured in Rockwell Hardness Tester in ‘C' scale and found to be 32.4 HRC and 50.5 HRC respectively, shown in Table 3.
4. Discussion On the outer surface of balance ball pin, there are multiple parallel scratches. On the expansion zone, it can be seen that the fatigue striations distribute along the circumference [8], which indicates that the balance ball pin was subjected to alternating shear stress and torque during the working process. Micro-fracture analysis shows that the outer surface exists the dense and uneven quench-hardened case. It can be deduced that during the quenching process, due to the large deformation rate and residual stress, cracks along circumference appeared on the surface of the hardened layer. When the balance ball pin was subjected to torque, the cracks expanded to the thick hardened layer, which resulted in stress concentration [9]. Finally, the cracks expanded towards the weak hardened layer. On the subsurface, with the alternating shear stress and torque, there were many holes sharpening, expanding and forming river patterns [10]. Stress 236
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 10. Sample metallographic tissue microstructures. Table 1 Chemical component of the balance ball pin. Samples
C
Si
Mn
P
S
Cr
Specification Composition
0.37–0.44 0.41
0.17–0.37 0.19
0.50–0.80 0.68
≤0.035 0. 015
≤0.035 0.005
0.80–1.10 0.96
Table 2 Results of mechanical tests. Tensile strength(MPa)
Yield strength(MPa)
Maximum elongation(%)
Reduction of area(%)
Elasticity modulus(GPa)
852
509
60.5
35.4
211
Table 3 Hardness test data. Test location
Measurement value/HRC
Average value/HRC
1/2 radius zone Surface zone
33.2/32.3/31.7 50.6/51.0/50.0
32.4 50.5
concentration points are concentrated around holes, which are easy to conduct the crack sources. Therefore, in the expansion zone, cracks formed around the holes. EDS result of the cracks on the outer surface showing the high oxygen content indicated that the oxidation improved after the outer surface worn, which led to the decrease of fatigue strength on the surface and improve wearing [11].
5. Conclusion and suggestion (1) (1)Balance ball pin failure belongs to early fatigue failure. The reason of fatigue failure is that uneven quench-hardened case on the balance ball pin's outer surface causes fatigue cracks initiation with the alternating shear stress and torque in the working process, and led to balance ball pin failure, finally. In order to prevent similar failure, reasonable heating frequency, heating time and cooling time should be controlled, and proper quenching liquid should be chosen to improve the quality of balance ball pin's surface. (2) (2)In order to reduce wearing of balance ball pin's surface, it is necessary to check the assembly of the connecting rod at regular intervals and replace the worn balance ball pin.
Acknowledgement This work was partially supported by doctoral fund of Southwest University of Science and Technology (Grant ID:13zx7153), PR China. 237
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
References [1] [2] [3] [4] [5] [6] [7] [8]
Q.H. Meng, Y.Z. Deng, L. Zhang, Fracture analysis on pins of loader, J. Fail. Anal. Prev. 4 (2009) 156–160. G.L. Sheldon, Unusual Failure of an automobile steering component, Failure Prevention and Reliability Conference, Dearborn, Mich. USA, 1983, pp. 27–31. Y.L.J. Lee, R. Hathaway, M. Barkey, Fatigue Testing and Analysis, Theory and Practice, Elsevier, New York, 2005. R.I. Stephens, A. Fatemi, R.R. Stephens, H.O. Fuchs, Metal Fatigue in Engineering, Wiley, New York, 2002. K. Koh, Seung, Fatigue failure analysis of an automotive link, J. Eng. Fail. Anal. 16 (2009) 914–922. H. Bayrakceken, S. Tasgetiren, K. Aslantas, Fracture of an automobile anti-roll bar, J. Eng. Fail. Anal. 13 (2006) 732–738. A.M. Heyes, Automotive component failures, J. Eng. Fail. Anal. 2 (1998) 129–141. N.W. Sachs, Understanding the surface features of fatigue fractures: how they describe the failure cause and the failure history, J. Fail. Anal. Prev. 5 (2) (2005) 11–15. [9] J.Y. Liao, Failure Analysis Of Metal Components, Chemical Industry Press, Beijing, 2010, pp. 73–74 (China). [10] Fractography, ASM Handbook, 12 ASM International, Materials Park, 2009. [11] B. Lonyuk, I. Apachitei, J. Duszczyk, The effect of oxide coatings on fatigue properties of 7475-T6 aluminium alloy, J. Surf. Coat. Technol. 201 (2007) 8688–8694.
238
Contents lists available at ScienceDirect
Engineering Failure Analysis journal homepage: www.elsevier.com/locate/engfailanal
Failure analysis of the balance ball pin in the car steering system ⁎
Ruidong Guo, Song Xue , Ailin Deng
T
College of Manufacturing Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
A R T IC LE I N F O
ABS TRA CT
Keywords: Failure analysis Balance ball pin Microcracks Fatigue fracture
A balance ball pin used in the car steering system was found broken into two pieces. An evaluation of the failed part was investigated to determine the cause of failure and assess its integrity. Mechanical properties tests of the material are conducted first. Macroscopic examinations, scanning electronic microscopy(SEM) examination, metallographic examination,hardness measurement and chemical composition analysis were all conducted. The results indicated that fatigue fracture is the main fracture mode, and the uneven quench treatment led to the inhomogeneous thickness of quench-hardened case. As a result, in the fluctuations load, microcracks along the circumferential direction emerged on the subsurface of the quench-hardened case. Moreover, due to poor assembly, the stabilizer bar didn't turn smoothly in the working and fitting surface was worn badly, where produced the large resistance, which is the main torque to the ball pin.
1. Introduction With the wider application of steering system in cars, the reliability and stability of it make a difference in the driving safety. The steering equilibrium units, including balance ball pin, transverse stabilizer bar and link rod and so on, play a key role in the process of driving. The balance ball pin, which is widely used in the steering system, is the most important connector among the transverse stabilizer bar constituting the link rod [1]. The balance ball pin transmits force from the transverse stabilizer bar to link rod. In the processing of working, balance ball pin bounce up and down or turns, and its angle has a larger swing. Therefore, the balance ball pin is subjected to great shear stress and easy to damage, which occurs frequently in driving. The processing technology of the balance ball pin is already mature. However, failure occurs particularly due to the manufacturing errors and misuse in working. The general types of car steering system failure include fatigue failure, impact fracture, wear and stress rupture [2]. In addition, there are several other factors that influence failure which include poor assembly, material defects, processing technology, improper heat treatment and subsurface defects in critical areas. Fatigue is one of the most commons automotive components failures [3]. Due to rubbing and wearing, a large torque is generated in the process of working. If the balance ball rubbing and wearing is serious, it is necessary to replace it. The failed balance ball pin prevents the steering system from functioning properly and causes the critical issues in driving safety [4]. The manufacturer received nearly 10 reports about the balance ball pin early fracture in one year, in order to prevent the similar case, investigate the early fracture cause in the automobile steering system is very important. Seung K. Koh [5] investigated a fatigue failure analysis of an automotive link. The analysis indicated the steering link rod occurred low-cycle fatigue failure at the middle region and the fracture crack is initiated at the highly stressed region. The fracture is taken place after a fatigue procedure under a combined bending and torsional stresses. Wassim Maktouf et al. [6] presented a fracture
⁎
Corresponding author. E-mail address: [email protected] (S. Xue).
https://doi.org/10.1016/j.engfailanal.2018.08.015 Received 7 March 2018; Received in revised form 4 May 2018; Accepted 13 August 2018 Available online 15 August 2018 1350-6307/ © 2018 Elsevier Ltd. All rights reserved.
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 1. Fractured balance ball pin.
analysis of automobile anti-roll bar. They found that the fractured of anti-roll bar in a ductile manner, caused a combined bending and torsional stress. The above analysis and investigations provide the probable root failure causes of different parts of the steering system. This will provide guidance for the study of this article. The cracked balance ball pin is shown in Fig. 1. The global assembly relation of the transverse stabilizer bar, the link rod and the balance ball pin is shown in Fig. 2(a) and (b). A ball pin consists of a threaded part and a fitting part. The balance ball pin is mainly subject to fluctuations load. Failure took place in the middle part which is made of 40Cr steel with a diameter of 18 mm. And this material is a mature material, which is widely used in automotive connectors. After quenching on the ball pin surface, the surface has higher hardness [7]. This paper presents a failure analysis case on a balance ball pin in the car steering system. Based on the factors influencing the failure of a ball pin, some suggestions for preventing these kinds of failures are proposed for subsequent production of this kind of balance ball pin. 2. Equipment and procedures The chemical composition of balance ball pin was determined by Energy Dispersive Spectrometer(EDS) chemical analysis. The mechanical properties were conducted. Micro-hardness profiles from surface to interior in various regions were made. The fracture surface was observed by visual examination and scanning electronic microscopy (SEM). The microstructure was observed by optical metallography. 3. Results 3.1. Visual inspection Failed balance ball pin is shown in Fig. 3. Multiple parallel scratches existing on the outer surface indicated the balance ball pin was worn. The fracture surface character is shown in Fig. 4, which is covered with corrosion. Three different feature zones of the fracture surface are designated as initial zone, expansion zone and final fracture zone, respectively. The extend zone shows the fine fatigue striation, which is a typical characteristic of fatigue failure. The final fracture zone which is near the fracture edge appears the shear lips. 3.2. Micro-fracture examination The examination around the ball pin surface revealed that there are a lot of parallel cracks, shown in Fig. 5(a). A lot of debris can be seen under high magnification, shown in Fig. 5(b). EDS result of the cracks is shown in Fig. 6,which indicates that crack surface is covered with the principal elements O and Fe. With the above analysis, it can be identified that the parallel cracks belong to fatigue cracks, and the debris on the cracks is mainly composed of iron oxides. The micromorphology of initial area, which indicates that there is no obvious crack source, lots of cracks propagating along the circumference and the river pattern, shown in Fig. 7(a) and (b). The outer surface exists the dense and uneven quench-hardened case, shown in Fig.7(c). There are lots of irregular cracks on the subsurface where the fatigue source is located and the cracks initiate,
Fig. 2. Macroscopic assembly: (a) Global assembly; (b) Local assembly. 233
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 3. Macro morphology of surface: (a) The surface is worn; (b) Multiple parallel scratchs.
Fig. 4. Macro morphology of the two matched fractures: (a)Fracture surface ‘A’; (b) Fracture surface ‘B’
Fig. 5. Multiple parallel cracks in the surface distribution near the starting crack area: (a) parallel cracks; (b) debris in cracks.
shown in Fig.7(d). There are many dead wood cracks in the expansion zone, shown in Fig.8. The secondary cracks where the white lump inclusions distribute are perpendicular to the radial distribution, shown in Fig.8(a) and (b). Moreover, the irregular holes appear around the tip of cracks, shown in Fig.8(c). The micromorphology of the final fracture zone indicates that the fracture is smooth and has the clear shear lips, shown in Fig.9(a). Besides, there is the typical dimple morphology with ductile tearing shape, shown in Fig.9(b). 3.3. Metallography The metallography of the microstructure of balance ball pin based on experimental study is shown in Fig.10. The results reveal the material microstructure of failure balance ball pin consisting of homogeneous tempered sorbate +small amount of granular carbide, which are based on GB/T13320-2007 standard assessment for level 1. 234
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 6. EDS: (a)Micro morphology of cracks; (b) EDS analysis.
Fig. 7. Microstructure of cracks initial area: (a) the circumferential cracks (b) the river pattern (c) the quench-hardened case (d) microstructure of subsurface.
3.4. Mechanical properties Table 1 shows the chemical composition of the failed balance ball pin and the requirement on the compositions content of these kinds of balance ball pin. It displayed that the chemical compositions of the failed ring gear meet the standard requirement. Specimen for tensile was machined from the failed balance ball pin according to SY/T5561-2008 standard. Table 2 shows the testing results, which indicates that mechanical properties of balance ball pin meet SY/T5561-2008 standard requirements.
3.5. Hardness measurement Hardness measurement of the 1/2 radius of the balance ball pin and the surface of the balance ball pin were implemented to verify if manufacture process meets the requirements. The hardness of quench influence layer is required in the range of 45 HRC–52 HRC. The core hardness of balance ball pin is specified in the range of 32–36 HRC. The hardness of the 1/2 radius of the balance ball pin 235
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 8. Microstructure of extend zone 4: (a) dead wood cracks, (b) secondary cracks and inclusions, (c) the irregular holes.
Fig. 9. Microstructure of the final fracture zone: (a) shear lips (b) dimples.
and the surface of the balance ball pin were measured in Rockwell Hardness Tester in ‘C' scale and found to be 32.4 HRC and 50.5 HRC respectively, shown in Table 3.
4. Discussion On the outer surface of balance ball pin, there are multiple parallel scratches. On the expansion zone, it can be seen that the fatigue striations distribute along the circumference [8], which indicates that the balance ball pin was subjected to alternating shear stress and torque during the working process. Micro-fracture analysis shows that the outer surface exists the dense and uneven quench-hardened case. It can be deduced that during the quenching process, due to the large deformation rate and residual stress, cracks along circumference appeared on the surface of the hardened layer. When the balance ball pin was subjected to torque, the cracks expanded to the thick hardened layer, which resulted in stress concentration [9]. Finally, the cracks expanded towards the weak hardened layer. On the subsurface, with the alternating shear stress and torque, there were many holes sharpening, expanding and forming river patterns [10]. Stress 236
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
Fig. 10. Sample metallographic tissue microstructures. Table 1 Chemical component of the balance ball pin. Samples
C
Si
Mn
P
S
Cr
Specification Composition
0.37–0.44 0.41
0.17–0.37 0.19
0.50–0.80 0.68
≤0.035 0. 015
≤0.035 0.005
0.80–1.10 0.96
Table 2 Results of mechanical tests. Tensile strength(MPa)
Yield strength(MPa)
Maximum elongation(%)
Reduction of area(%)
Elasticity modulus(GPa)
852
509
60.5
35.4
211
Table 3 Hardness test data. Test location
Measurement value/HRC
Average value/HRC
1/2 radius zone Surface zone
33.2/32.3/31.7 50.6/51.0/50.0
32.4 50.5
concentration points are concentrated around holes, which are easy to conduct the crack sources. Therefore, in the expansion zone, cracks formed around the holes. EDS result of the cracks on the outer surface showing the high oxygen content indicated that the oxidation improved after the outer surface worn, which led to the decrease of fatigue strength on the surface and improve wearing [11].
5. Conclusion and suggestion (1) (1)Balance ball pin failure belongs to early fatigue failure. The reason of fatigue failure is that uneven quench-hardened case on the balance ball pin's outer surface causes fatigue cracks initiation with the alternating shear stress and torque in the working process, and led to balance ball pin failure, finally. In order to prevent similar failure, reasonable heating frequency, heating time and cooling time should be controlled, and proper quenching liquid should be chosen to improve the quality of balance ball pin's surface. (2) (2)In order to reduce wearing of balance ball pin's surface, it is necessary to check the assembly of the connecting rod at regular intervals and replace the worn balance ball pin.
Acknowledgement This work was partially supported by doctoral fund of Southwest University of Science and Technology (Grant ID:13zx7153), PR China. 237
Engineering Failure Analysis 94 (2018) 232–238
R. Guo et al.
References [1] [2] [3] [4] [5] [6] [7] [8]
Q.H. Meng, Y.Z. Deng, L. Zhang, Fracture analysis on pins of loader, J. Fail. Anal. Prev. 4 (2009) 156–160. G.L. Sheldon, Unusual Failure of an automobile steering component, Failure Prevention and Reliability Conference, Dearborn, Mich. USA, 1983, pp. 27–31. Y.L.J. Lee, R. Hathaway, M. Barkey, Fatigue Testing and Analysis, Theory and Practice, Elsevier, New York, 2005. R.I. Stephens, A. Fatemi, R.R. Stephens, H.O. Fuchs, Metal Fatigue in Engineering, Wiley, New York, 2002. K. Koh, Seung, Fatigue failure analysis of an automotive link, J. Eng. Fail. Anal. 16 (2009) 914–922. H. Bayrakceken, S. Tasgetiren, K. Aslantas, Fracture of an automobile anti-roll bar, J. Eng. Fail. Anal. 13 (2006) 732–738. A.M. Heyes, Automotive component failures, J. Eng. Fail. Anal. 2 (1998) 129–141. N.W. Sachs, Understanding the surface features of fatigue fractures: how they describe the failure cause and the failure history, J. Fail. Anal. Prev. 5 (2) (2005) 11–15. [9] J.Y. Liao, Failure Analysis Of Metal Components, Chemical Industry Press, Beijing, 2010, pp. 73–74 (China). [10] Fractography, ASM Handbook, 12 ASM International, Materials Park, 2009. [11] B. Lonyuk, I. Apachitei, J. Duszczyk, The effect of oxide coatings on fatigue properties of 7475-T6 aluminium alloy, J. Surf. Coat. Technol. 201 (2007) 8688–8694.
238