Microstructure and properties of bobbin-tool FSW for the 7075 aluminum alloy

XIE Li; WANG Jiangtao; LU Yalin; SUN Lingyan; YANG Xiaohong

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Microstructure and properties of bobbin-tool FSW for the 7075 aluminum alloy
Vol. 49, Issue 2, Pages: 55-59(2019)
Published：2019
DOI：
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DOI：

XIE Li, WANG Jiangtao, LU Yalin, et al. Microstructure and properties of bobbin-tool FSW for the 7075 aluminum alloy[J]. Eletric Welding Machine2019, 49(2): 55-59. DOI：

摘要

对7075铝合金双轴肩搅拌摩擦焊(Friction Stir Welding

FSW)焊缝的组织、力学性能和电化学腐蚀性能进行研究。结果表明:焊缝区从内到外依次为焊核区、热机影响区、热影响区和母材区

焊核区为细小的等轴晶组织

热机影响区为粗大的变形组织

热影响区为粗化的母材条带组织;由于晶粒的细化和机械加工硬化作用

整个区域硬度明显提高

但由于焊核后退侧存在不均匀的"混晶"组织

导致焊缝强度无明显提高

抗拉强度仅为267.84 MPa;垂直于焊缝方向表面的耐腐蚀性能优于平行于焊缝方向的表面

但焊缝区的耐腐蚀性能比母材差。

Abstract

Microstructure

mechanical properties and electrochemical corrosion properties of bobbin-tool friction stir welding（FSW）for the 7075 aluminum alloy were studied. The results show that

the welding zone is composed of weld nugget

thermo-mechanically affected zone

heat affected zone and base metal. The weld nugget is composed of fine equiaxed grains

the heat affected zone is composed of coarse deformed grains and the heat affected zone is coarse microstructure of base metal. Due to grain refinement and mechanical work hardening

the hardness of welding zone is markedly improved. However

the tensile strength has no significant increase

which is only 267.84 MPa. The boundary of retreating side and base metal is fuzzy

consisted of inhomogeneous mixed-grain microstructure

which is responsible for the low strength. The corrosion resistance of the surface perpendicular is better than that of the parallel to the weld joint

but the corrosion resistance of the welding zone is worse than that of the base metal.