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<p>Joining dissimilar metal sheets with contrast mechanical properties is in high demand nowadays in the automotive industry. Self-piercing riveting (SPR) is a joining technology which is very efficient for dissimilar metal and different sheet thickness joining. This study investigated the performance of advance high strength steels (AHSS) used as the top sheet and AA6061 as the bottom sheet. High-strength steels include DP780, DP980, and 1180MS, which are increasingly available on the market, but very rarely discussed. The study focused on investigating the failure modes and mechanisms in AHSS-aluminum sheet joints under tensile and fatigue lap-shear loads. The effects of corrosion that commonly occur in AHSS are involved through salt spray treatment with an exposure duration of 168 to 1176&#xa0;h. The lap shear test results showed that after 1176&#xa0;h 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 (interlocking failure); DP980 decreased by 15.55% and 22.81%, with failure mode identified as Mode B (top sheet tearing); and 1180MS decreased by 7.14% and 27.11%, with failure mode identified as Mode C (combination of interlocking failure and top sheet tearing). In short-term corrosion (168&#xa0;h), the fatigue test results showed that under high fatigue load, the mean fatigue life decreased 10.34%, 8.77%, and 1.54% for DP780-AA6061, DP980-AA6061, and 1180MS-AA6061 joints respectively, but decreased 4.08%, 15.22%, and 16.24% respectively under low fatigue load. Meanwhile for long-term corrosion (1176&#xa0;h), the percentage of mean fatigue life reductions were relatively similar for the three material joint combinations. Two different failure modes were observed during lap-shear fatigue tests. The first mode is a failure initiated by a crack in the center of the rivet hole in the bottom sheet, and the second is induced by a crack in the rivet hole close to the rivet leg. In addition, the microstructure examinations of failed bottom sheets were provided to explain the failure mechanisms through the morphology characteristics. 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.</p>

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Failure mechanisms of self-piercing riveting joints under salt spray corrosion of three dissimilar steel-aluminum hybrid sheets

  • 期刊论文

  • 发表日期：

    2026年2月25日

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  • Po-Chin Hsu,
  • Imang Eko Saputro,
  • Intan Mardiono,
  • Yu-Chieh Wang,
  • Hao-Han Zhang,
  • Yiin-Kuen Fuh,
  • Teng-Shih Shih

摘要

Joining dissimilar metal sheets with contrast mechanical properties is in high demand nowadays in the automotive industry. Self-piercing riveting (SPR) is a joining technology which is very efficient for dissimilar metal and different sheet thickness joining. This study investigated the performance of advance high strength steels (AHSS) used as the top sheet and AA6061 as the bottom sheet. High-strength steels include DP780, DP980, and 1180MS, which are increasingly available on the market, but very rarely discussed. The study focused on investigating the failure modes and mechanisms in AHSS-aluminum sheet joints under tensile and fatigue lap-shear loads. The effects of corrosion that commonly occur in AHSS are involved through salt spray treatment with an exposure duration of 168 to 1176 h. The lap shear test results showed that after 1176 h 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 (interlocking failure); DP980 decreased by 15.55% and 22.81%, with failure mode identified as Mode B (top sheet tearing); and 1180MS decreased by 7.14% and 27.11%, with failure mode identified as Mode C (combination of interlocking failure and top sheet tearing). In short-term corrosion (168 h), the fatigue test results showed that under high fatigue load, the mean fatigue life decreased 10.34%, 8.77%, and 1.54% for DP780-AA6061, DP980-AA6061, and 1180MS-AA6061 joints respectively, but decreased 4.08%, 15.22%, and 16.24% respectively under low fatigue load. Meanwhile for long-term corrosion (1176 h), the percentage of mean fatigue life reductions were relatively similar for the three material joint combinations. Two different failure modes were observed during lap-shear fatigue tests. The first mode is a failure initiated by a crack in the center of the rivet hole in the bottom sheet, and the second is induced by a crack in the rivet hole close to the rivet leg. In addition, the microstructure examinations of failed bottom sheets were provided to explain the failure mechanisms through the morphology characteristics. 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.