| dc.description.abstract | This study investigates the effects of salt spray environments on the quality and strength of three different types of dissimilar Self-Piercing Riveting (SPR) joints. Mechanical testing and failure mechanism analysis were conducted on SPR specimens under salt spray corrosion conditions. Taking advantage of the high strength, rapid processing, and suitability for dissimilar materials offered by SPR technology, the specimens underwent the following tests. The lap shear test results showed that after 1176 hours of salt spray corrosion, the peak load and energy absorption values of the three dissimilar joints changed as follows: DP780 decreased by 24.67% and 16.48%, with failure mode identified as Mode A (ILF, interlocking failure); DP980 decreased by 15.55% and 22.81%, with failure mode identified as Mode B (mixed ILF and TST, top shear tearing); and 1180MS decreased by 7.14% and 27.11%, with failure mode identified as Mode B (mixed ILF and TST). In addition, the fatigue test results showed that after 1176 hours of salt spray corrosion, under a fatigue load of 2.25 kN, the fatigue life of DP780, DP980, and 1180MS decreased by 68.3%, 61.3%, and 58.9%, respectively. Furthermore, under no corrosion (0 hours) treatment and high fatigue load conditions (4.5 kN), failure mode α was triggered, defined as ＂cracks initiated around rivet holes causing base sheet failure.＂ In contrast, under long-term salt spray (1176 hours) treatment and low fatigue load conditions (1.75 kN), failure mode γ was triggered, defined as ＂cracks initiated at the substrate overlap area causing base sheet failure.＂ Under mixed conditions of salt spray and fatigue load (0 hours, 1.75 kN or 1176 hours, 2.5 kN), failure mode β may be triggered, defined as ＂cracks initiated at the edge of the rivet hole causing base sheet failure.＂ The main contributions of this study includes providing beneficial insights on the failure mechanisms of dissimilar steel-aluminum hybrid sheets (DP780, DP980, 1180MS) SPR joints under lap shear and fatigue loads with salt environment exposures. This study elucidates the interrelationships among dissimilar joints, salt spray corrosion, mechanical properties, and failure mechanisms. The findings offer valuable benchmarks for material selection process in implementing dissimilar sheets SPR joint for automotive applications, thereby reducing costs in the automotive industry. Through actual validation, this study elucidates the interrelationships among dissimilar joints, salt spray corrosion, mechanical properties, and failure mechanisms. | en_US |