A Study on Fatigue Strength Improvement of Aluminum Alloy Resistant Spot Welds by Cold Working
Resistance spot welds (RSW) have been widely used in the sheet metal joining process due to high productivity, low cost and convenience. The application of aluminum alloys in automobile manufacturing has resulted in the reduction of weight in vehicle, fuel economy and improvement of drivability and driving performance. Therefore, the resistance spot weld (RSW) process has attracted attention to fabrication of aluminum structures. However, applications of Al RSW are limited due to the unreliable durability of the weld-bonded joints. This study presents an experimental investigation on the use of a post-weld cold working process to improve the fatigue strength of Al RSW. The post-weld cold working process includes a pair of uniquely shaped indenters that are pressed or driven into the structure in order to induce the compressive residual stresses around the RSW. The mechanical properties of the post-weld cold worked Al RSW were investigated, including the experimental results of fatigue. The effect of the post-weld cold working process parameters on the fatigue strength of the Al RSW was also investigated. Comparisons of the mechanical properties and qualitative results between the as-welded RSW specimens and the post-weld cold worked RSW specimens of each post-cold working parameter have been carried out. Also, discussions on the experimental results using the finite element method (FEM) for the post-weld cold working parameters are performed.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
D. Kim et al., "A Study on Fatigue Strength Improvement of Aluminum Alloy Resistant Spot Welds by Cold Working", Materials Science Forum, Vols. 539-543, pp. 3961-3966, 2007