搅拌头偏移对Ti/Al异种金属搅拌摩擦焊接头成形及拉伸强度的影响

Effect of Tool Offset on Weld Formation and Tensile Strength of Friction Stir Welded Ti/Al Dissimilar Metal Joints

摘要:

采用搅拌摩擦焊(FSW)完成了3 mm厚TC4钛合金和2A14-T14铝合金的连接,研究了搅拌头偏移对接头的成形及拉伸性能的影响。结果表明在搅拌头向铝合金侧的偏移对接头的最大抗拉强度有显著的影响。接头最大抗拉强度随搅拌头的偏移量的增加逐渐升高。在偏移量为2.0 mm、搅拌头转速从400 r/min增加到700 r/min时,接头的最大抗拉强度逐渐降低。在偏移量为2.5 mm、接头的最大抗拉强度随转速的增加逐渐升高。当在搅拌头转速为700 r/min, 焊接速度为60 mm/min时,所得接头强度最高,约347 MPa,为铝合金母材的83 %。接头的断裂位置和拉伸强度均取决于微观组织和金属间化合物。对于强度最高的接头,由于TiAl相的生成,接头于铝合金侧热影响区发生断裂。

Abstract:

3mm thick TC4 titanium alloy and 2A14-T4 aluminum alloy were well joined by friction stir welding (FSW), and the influence of tool offset on weld formation and tensile property of the joints was investigated. The results show that tool offset to the Al side has significant influence on ultimate tensile strength (UTS) of the joints. With the increase of tool offset, the UTS increases gradually. When the tool offset is 2.0mm, the UTS of the joint decreases with increasing tool rotation speed from 400r/min to 700r/min. However, when the tool offset is increased to 2.5mm, the UTS of the joint increase with the increase of tool rotation speed. A tool rotation speed of 700r/min and a welding speed of 60mm/min is matched, the highest UST of 347MPa of the joint is obtained, which reaches to about 83% of Al matrix. The tensile results prove that the fracture location and tensile strength of the joints mainly depend on microstructure and intermetallic phases. For the joint with the highest strength, the fracture occurs in the heat affected zone (HAZ) of Al matrix due to brittle TiAl phase formed in the joint.