TA1钛合金自冲铆接头力学性能及微动行为

Mechanical Performance and Fretting Behavior of Self-piercing Riveted Joint of TA1 Titanium Alloy

本工作以TA1自冲铆接头为研究对象,基于拉伸-剪切和疲劳试验分析了接头的力学性能,并采用扫描电镜从微观层面研究了接头的拉伸-剪切失效机理、疲劳失效机理及微动行为。结果表明:拉伸-剪切失效模式为铆钉腿部从下板拉脱,铆钉颈部存在不同程度的断裂。疲劳失效模式主要为上板断裂失效,其疲劳极限约为1.18kN。疲劳裂纹从上板与铆钉头接触部位萌生,在持续微动磨损及疲劳循环应力作用下,沿板厚和板宽方向不断扩展,直至接头疲劳断裂。微动磨损的剧烈程度直接影响接头疲劳失效模式。上板与铆钉头接触区的微动磨损源于板宽W区域,随着微动过程的不断进行,逐步向板长L区域扩展。

The present work mainly focused on the self-piercing riveted(SPR)joint of TA1 titanium alloy.The tensile-shear test and fatigue test were conducted to analyze the mechanical performance of the joints,and the tensile-shear failure mechanism,fatigue failure mechanism and fretting behavior of the joints were investigated at a microscopic level by scanning electron microscope.The results exhibited that the tensile-shear failure mode assumed rivet shank pull-out from the bottom sheet and some degree of fracture located at the rivet neck,while the main fatigue failure mode was fracture of the upper sheet whose fatigue limit was approximately 1.18 kN.Fatigue cracks initiated at pierced sheet surface’s contact site with rivet head,and were propagated along the sheet thickness direction and sheet width direction under continuous fretting wear and fatigue cyclic stress,and finally resulted in joint break.The severity of fretting wear could influence fatigue failure mode of the joints.Fretting wear of the upper sheet initiated from W direction of sheet width,and spread gradually to L direction of sheet length with fretting wear process.