Characteristics of Fretting Damage in Hybrid DP780/AA6061 Self-piercing Riveted Joints

doi:10.3901/JME.2020.06.169

Abstract

Abstract: The self-piercing riveting (SPR) processes between the high strength steel DP780 and aluminum alloy AA6061 sheet are studied. The DP780/AA6061(SA) and AA6061/DP780(AS) joints with different combinations are fabricated respectively. The high-cycle fatigue tests are carried out and then comparative analysis about the fatigue properties and failure behaviors are conducted. Further, the fretting damage mechanism of the corresponding joints are discussed systematically using the micro detective methods. The results show that the fatigue strength of the AS joints is significantly better than that of the SA joints. The SA joints fail in locked sheet and the AS joints fail due to the rivet fractured. The fretting wear mainly exists in the contact surfaces between the proximal end of pierced sheet and the distal end of locked sheet, the proximal end of pierced sheet and the far end of locked sheet, as well as the rivet and the proximal end of locked sheet. The fretting wear can result in the fatigue cracks to initiate in both the rivet and the locked sheet of the SA and AS joints. However, due to the different material properties between the high strength steel and the aluminium sheet, the propagation path and rate of the fatigue crack on the rivet and the proximal end of locked sheet are affected, which finally bring the different fatigue failure modes.

Key words: self-piercing riveting, aluminium alloy, high strength steel, fatigue property, fretting damage

CLC Number:

TG938

WEI Wenjie, HE Xiaocong, ZHANG Xianlian, LU Jiawei. Characteristics of Fretting Damage in Hybrid DP780/AA6061 Self-piercing Riveted Joints[J]. Journal of Mechanical Engineering, 2020, 56(6): 169-175.

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