摘要
研究了铝合金2024-T4搅拌摩擦焊(FSW)搭接接头的微观组织特征和疲劳性能。结果表明,搭接接头后退侧热力影响区晶粒变形程度较前进侧严重。疲劳试样断裂位置均位于弱连接缺陷向上"拉起"较严重的焊核区后退侧。当应力比为0.1时,铝合金搅拌摩擦焊搭接接头对应于95%存活率的疲劳强度特征值Δσk为18.25MPa,与铝合金熔焊搭接接头的Δσk为13.92MPa相比,增加了31.11%。与此同时,FSW搭接接头疲劳S-N曲线斜率m为5.39,大于熔焊接头所对应的S-N曲线斜率范围3.0～3.5,可见在长寿命区搭接接头的疲劳性能优于熔焊接头。搭接接头的裂纹源位于搭接接头上板底部位置的表面缺陷或者强化相颗粒处,对应于弱连接缺陷处。
Microstructures and the fatigue performances of AA6061-T6 friction-stir-welded overlap joints were investigated. It was shown that the grain deformation of TMAZ was more serious in the retreating side than that in the advancing side. All the fatigue fra ture sites of specimens were initiated at the more serious booking defect, in which the up-trend was larger. When R was equal to 0.1 , the fatigue strength △σk of Aluminum alloy FSW overlap joints was 18.25MPa for the 95% survival probability, which meant an increase of 31.11% as compared with the /△σk 13.92MPa of Aluminum alloy fusion overlap welded joints. Besides, it was observed that the slope value m for the S-N curve of the FSW joints was 5.39, which was higher than that of the fusion welded joint set to 3.0- 3.5. So the FSW joint had better fatigue strength than that of the fusion welded joints in the long life region of fatigue performance. Fatigue cracking was initiated at the surface defects or strengthening phase particles locating at the bottom of the upper plate, which were corresponded to the hooking position.
出处
《航空材料学报》
EI
CAS
CSCD
北大核心
2012年第3期51-56,共6页
Journal of Aeronautical Materials
基金
国家自然科学基金资助项目(50775159)
关键词
铝合金
搅拌摩擦焊
搭接接头
微观组织
疲劳性能
A1 alloys
friction stir welding
overlap joints
microstructures
fatigue properties
