厚板铝合金FSW和MIG焊接接头疲劳性能

摘要

对厚度10 mm的6082-T6铝合金搅拌摩擦焊（FSW）和MIG焊接接头的疲劳强度进行了试验研究,并与6082-T6母材疲劳性能进行了对比分析.结果表明,6082-T6母材的疲劳S-N曲线最高、MIG焊接接头S-N曲线度最低,而FSW接头的疲劳S-N曲线近似位于两者之间;在高应力区FSW疲劳强度低于MIG焊接接头、而在低应力区高于MIG焊接接头.大部分FSW试样疲劳裂纹启始于焊缝根部的＂弱连接＂缺陷,采用机械加工去掉1.4 mm厚度焊缝根部材料后,FSW疲劳强度明显提高并接近母材数据.厚板6082-T6铝合金FSW焊缝根部质量控制是影响疲劳性能的关键因素.%The fatigue properties of FSW and MIG welded joints for AA6082-T6 aluminum alloy of 10 mm thickness were investigated by the fatigue S-N curves testing method,and these prperties were also compared to that of AA6082-T6 base material.It was shown that the fatigue S-N curve of AA6082-T6 base material was the highest,the S-N curve of MIG welded joints was the lowest,and the S-N curve of FSW joint was between the two curves.In high stress range,the fatigue strength of FSW was lower than that of MIG welded joints,while in low stress range,it was higher than the MIG welded joints.It indicated that most of the FSW specimens were initially fractured at the weld,caused by the ＂weak-bonding＂ defects and the fatigue strength of FSW joint increased apparently,which is close to the values of base material after removing one layer of weld root material with thickness of 1.4 mm.Thus it can be verified that the quality of the weld root sites for the single-side FSW welded joints of AA6082-T6 aluminum alloys thick plate should be the key factor to influence the fatigue properties of FSW joint.