TA1异质自冲铆接头力学性能及失效机理

Mechanical Properties and Failure Mechanisms of Self-piercing Riveted Joints of Dissimilar Sheets for TA1 Titanium Alloy

通过自冲铆接对比试验获得接头最优铆接参数,并以此制备TA1钛合金板分别与Al5052铝合金板和H62铜合金板的异质自冲铆接头。通过静力学实验和疲劳实验研究异质接头的力学性能,并运用疲劳三参数经验公式拟合S-N曲线,最后利用扫描电镜和能谱仪进行断口分析和能谱分析进而研究接头的疲劳失效机理。结果表明,TA1-H62(STH)接头静失效载荷优于TA1-Al5052(STA)接头;且前者在低载荷下疲劳寿命优于后者,STA接头则在高载荷下优势明显。STA接头疲劳失效模式为下板断裂,STH接头则出现了两种失效模式;两板间及铆钉与上下板之间接触区域发生的剧烈微震磨损是导致疲劳裂纹萌生的主要原因。

The optimum riveting parameters were obtained through self-piercing riveting(SPR)contrast tests,and the SPR joints in dissimilar sheets about TA1 titanium alloys were fabricated with the optimum parameters.The mechanical properties were studied with the static tests and fatigue tests,and the S-N curves were fitted by the fatigue empirical formula of three parameters.Finally,the fracture analysis and spectrum analysis were conducted with scanning electron microscope and alpha ray spectrometer to study the fatigue failure mechanisms.The results showed that the peak load of STH joints was superior to that of STA joints.STH joints had a better fatigue life at low fatigue loads,but STA joints was better at high fatigue loads.The fatigue failure modes of STA joints were the locked sheet fracture,and two failure modes occurred in STH joints.The severe fretting wear taken place between the two sheets or the contact area of the rivet and sheets was the main cause of the fatigue crack initiation.