| 摘要: | 本研究探討了鹽霧環境對三個異種自衝鉚接（SPR, Self-Piercing Riveting）接頭的質量和強度影響。在鹽霧腐蝕條件下，對SPR試樣進行了機械測試和失效機制分析。基於SPR鉚接技術具有高強度、快速加工以及適合異材質的優勢，試片進行了以下測試。搭接剪切測試結果顯示，在經過1176小時的鹽霧腐蝕後，三個異種SPR接頭的峰值負載與能量吸收值變化如下：DP780分別下降了24.67%和16.48%，失效模式為模式A(ILF, Interlocking Failure)；DP980下降了15.55%和22.81%，失效模式為模式B(mixed ILF and TST, Top Shear Tearing)；1180MS下降了7.14%和27.11%，失效模式為模式B(mixed ILF and TST)。此外，疲勞測試結果顯示，在經過1176小時的鹽霧腐蝕後，在2.25 kN的疲勞負載下，DP780、DP980和1180MS的疲勞壽命分別下降了68.3%、61.3%和58.9%。此外，在無鹽霧（0小時）條件和高疲勞負載（4.5 kN）條件下，觸發了失效模式α，定義為「鉚釘孔周圍出現裂紋，導致基板失效」；相反，在長期鹽霧（1176小時）處理和低疲勞負載（1.75 kN）條件下，觸發了失效模式γ，定義為「基板重疊區域出現裂紋，導致基板失效」。在鹽霧和疲勞負載的混合條件下（0小時，1.75kN或1176小時，2.5kN），可能觸發模式β，定義為「鉚釘孔邊緣出現裂紋，導致基板失效」。本研究的主要貢獻包括提供有益的見解，分析在搭接剪切和疲勞負載及鹽霧環境暴露下，不同鋼鋁混合板材（DP780、DP980、1180MS）SPR接頭的失效機制。本研究闡明了不同接頭、鹽霧腐蝕、機械性能及失效機制之間的相互關係。這些研究結果為在汽車應用中選用不同板材進行SPR接頭設計提供了有價值的參考標準，從而降低汽車行業的成本。通過實際驗證，本研究闡明了異種接頭、鹽霧腐蝕、機械性能與失效機制之間的相互關係。;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. |
