铝合金表面状态对搅拌摩擦焊接头组织和性能的影响

研究了铝合金表面状态对搅拌摩擦焊焊接接头组织和性能的影响。试验结果表明:试板表面油污的存在使得焊接接头强度下降为母材的60%左右,同时显著降低接头的塑性;试板表面的氧化膜和油污还会造成焊核区及焊缝前进侧的残余间混结合线缺陷。对焊接接头拉伸断口进行扫描电镜观察发现:拉伸试样的断口中存在油污和A l2O3的聚集物,这些聚集物会成为拉伸时的裂纹源。断口和力学性能综合分析表明:铝合金表面的油污和氧化膜都会降低搅拌摩擦焊接头的强度和塑性。

Effects of Surface State of Aluminum Alloy on Microstructure and Property of Friction Stir Welding Joint

The effects of the surface state of aluminum alloy on the microstructure and the property of the friction stir-welding joint are studied.The existence of greasy dirt on the base material surface may cause the descending of the joint property to 60% of the base material,and has obvious influence on the plastic property of the joint.In addition,the oxide layer and greasy dirt on the base material surface may cause JLR flaw in the stir zone and the weld advanced side.The SEM microstructure features are observed in weld tensile fractures.Results show that in the fractures of tensile samples,the greasy dirt and Al2O3 polymer become the crack source in the tensile test.The comprehensive analysis of fractures and properties shows that both greasy dirt and oxide layer on the surface of aluminum alloy can reduce the intensity and the plastic property of the friction stir welding joint.