TA1钛合金单搭自冲铆接头微动磨损机理

Fretting Wear Mechanisms of Single Lap Self-piercing Riveted Joint in TA1 Titanium Alloy

对TA1钛合金单搭自冲铆接头进行疲劳实验研究接头失效形式;用扫描电子显微镜和X射线能谱线扫描研究铆钉各部位微动磨损程度的差异和接头微动磨损机理;采用威布尔分布验证数据有效性。结果表明:接头疲劳失效形式主要为上板断裂,高周疲劳均为上板断裂,低周疲劳为上下板混合断裂;微动磨屑包含氧、钛、锌和锡元素,铆钉头部微动磨损程度高于铆钉腿部。微动磨损区出现严重脱层、微动磨屑堆积和微裂纹萌生等现象,随着微动磨损及剪切力共同作用导致接头断口部位出现大量微裂纹并逐步沿深度和宽度方向扩展为宏观裂纹,最终导致接头疲劳失效。

The fatigue test of single lap self-piercing riveted joints in TA1 titanium alloy were performed to investigate the fai- lure mode of the joints. The difference of fretting wear on rivet surface and fretting wear mechanism of the joints were studied by scanning electron microscope （SEM） and energy dispersive X-ray （EDX） line scanning. The validity of fatigue data was verified by Weibull distribution. The results showed that the main failure mode of the joints was the upper sheet fracture, the failure mode of the joints with high fatigue cycle were the upper sheet fracture, the failure mode of the joints with low fatigue cycle were the upper sheet and bottom sheet fracture. Fretting debris included O, Ti, Zn and Sn elements, the degree of fretting wear on rivet head was severer than that of rivet shank. Severe delamination, fretting debris accumulation and micro cracks initiation occurred in fretting wear re- gion. Large amount of micro cracks near the fracture part initiated and propagated along depth and width directions during fretting wear process and shear force, finally caused the fatigue failure of the joints.