Fatigue enhancement of post-weld cold-worked low-carbon steel resistance spot welds

Abstract

Automotive manufacturers typically use resistance spot welding (RSW) for their automotive body sheet metal assembly. RSW offers a number of advantages over other sheet-metal-joining techniques, including high speed, ease of automation, and energy efficiency. However, one of the major concerns of spot weld joints is fatigue. Recently, a fatigue enhancement process for resistance spot welds, namely a post-weld cold-working process, has been introduced and has given significant improvement in fatigue lives of resistance spot welds. The post-weld cold-working process imparts compressive residual stresses around the joint, which can benefit the fatigue strength. This paper presents experimental and numerical investigations on the use of the post-weld cold-working process to improve the fatigue strength of low-carbon steel resistance spot welds. The effect of the post-weld cold-working process parameters on fatigue strength is investigated and the optimum process condition is proposed. In addition, a finite element analysis is carried out to evaluate the residual stress distribution after cold working.