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采用光纤激光-变极性TIG复合填丝焊接4mm厚的A7N01铝合金,研究了焊接电流、焊接速度对焊缝成形及气孔的影响规律,同时分析了优化工艺参数条件下焊接接头的显微组织和力学性能。结果表明,随着焊接电流的增加,焊缝正面熔宽增加,背面熔宽基本不变;而焊接速度降低,焊缝正面和背面熔宽均增加,焊缝内部气孔减少;且在激光功率为6kW、焊接电流为180A、焊接速度为4m/min、送丝速度为4m/min时,获得成形良好内部无缺陷的焊接接头;焊缝横截面呈典型的上宽下窄的特征,从熔合线至焊缝中心,焊缝显微组织依次为细小等轴晶、柱状晶、等轴树枝晶形态,且焊缝中心的等轴树枝晶晶粒尺寸自上而下逐渐减小,二次枝晶逐渐弱化;焊缝区的硬度值低于母材,存在接头软化现象,其接头抗拉强度均值为369.8 MPa,约为母材的83%,延伸率约为4.0%,拉伸断裂于焊缝区,拉伸断口呈典型的韧性断裂特征。
A7N01 aluminum alloy with 4mm thickness was welded by fiber laser - variable polarity TIG composite filler wire. The influence of welding current and welding speed on the formation of weld and porosity was studied. The microstructure of welded joint under optimized process parameters was analyzed. And mechanical properties. The results show that with the increase of welding current, the front weld width increases and the back weld width remains unchanged. However, the welding speed decreases, the weld front and back weld width increase, and the internal porosity of the weld decreases. When the laser power is 6kW, the welding current is 180A, the welding speed is 4m / min and the wire feeding speed is 4m / min, the well-formed internal weld- To the weld center, the weld microstructure followed by fine equiaxed, columnar, equiaxed dendritic morphology, and weld center equiaxed dendritic grain size decreases from top to bottom, the secondary dendrite The hardness value of the weld zone is lower than the base metal, there is softening of the joint, the average tensile strength of the joints is 369.8 MPa, about 83% of the base metal, the elongation rate of about 4.0%, tensile fracture in the weld Zone, tensile fracture showed a typical ductile fracture characteristics.