TA1纯钛与1420铝锂合金异质薄板自冲铆接微动疲劳特性

基于自冲铆接技术研究TA1工业纯钛(TA1)与1420铝锂合金(AL1420)异质薄板组合的可铆性,并采用硬度≥44HRC和≥46HRC的铆钉分别制备TA1/AL1420 (TAF),AL1420/TA1(ATF)和TA1/AL1420(TAS) 3组接头。在拉伸-剪切实验的基础上进行了高周疲劳实验,拟合出各组接头的F-N曲线,进一步利用电子扫描显微镜和能谱仪分析了各组接头的微动磨损机理。结果表明:ATF接头的疲劳强度相对较优,TAS接头则在中高载荷水平下优于TAF接头;各组接头的疲劳失效均始于微动磨损区域,微动磨损导致疲劳裂纹的萌生;微动磨屑现象的剧烈程度是影响疲劳强度的重要因素。在不同疲劳载荷水平下,发生剧烈微动磨损的区域不同,使得疲劳裂纹的萌生区域存在差异,最终导致同种接头出现不同的失效模式。

Fretting fatigue characteristics of self-piercing riveting in dissimilar sheets of TA1 pure titanium and 1420 aluminum-lithium alloys

Using self-piercing riveting(SPR),the joinability of dissimilar sheet combinations in TA1 pure titanium(TA1)and 1420 aluminium-lithium(AL1420)alloy sheets were studied.SPR joints of TA1/AL1420(TAF),AL1420/TA1(ATF)and TA1/AL1420(TAS)were fabricated from different rivets in the hardness of≥44HRC and≥46HRC,correspondingly.High cycle fatigue tests were conducted based on tensile-shear tests.Then F-N curves of different joints were fitted.Furthermore,fretting wear mechanisms of SPR joints were analysed by scanning electron microscopy(SEM)and energy disperse spectroscopy(EDS).Results show that the fatigue strength of ATF joints is better than that of the other joints.And the fatigue strength of TAS joints is superior to TAF joints at middle and high load level.Fatigue failure of all joints initiates in fretting wear areas,and fatigue wear results in fatigue crack initiation.Fretting degree is an important factor for affecting fatigue strengths.The serious fretting wear areas are different at different load levels,and then the initiated areas of fatigue cracks are different.Finally,different failure modes occur in the same SPR joints.