厚板镁合金冷金属过渡焊工艺及接头力学性能

Cold metal transition welding technology and mechnical properties of weded joint of thick plate magnesium alloy

采用CMT焊对厚6 mm的AZ31B镁合金板材进行对接焊,优化后的焊接工艺参数为:焊接电流169 A,送丝速度5.4 m/min,焊接速度0.47 m/min,对口间隙1.6 mm。采用该焊接参数可以获得良好的焊缝成形,没有焊接缺陷,焊接过程稳定无飞溅。对接头的静载抗拉强度和疲劳性能进行了试验,分析了接头组织对焊接接头的抗拉强度和疲劳强度的影响。结果表明:AZ31B镁合金CMT焊接接头的静载抗拉强度为212.9 MPa,接头在2×106循环次数下的疲劳强度为16.72 MPa,仅为其抗拉强度的7.8%,远低于其抗拉强度。

6 mm thick AZ31 B magnesium plates were butt welded by cold metal transition(CMT) welding process with the diameter 1.6 mm WE-33 M feed wire. When the optimed parameters of CMT welding using the welding current was 169 A, the wire feeding speed 5.4 m/min, the welding speed 0.47 m/min, the weld gap 1.6 mm, fine appearance of the weld seam and stable welding process without no splash could be realized. The tensile strength and fatigue properties of the joint were tested, and the effect of welding microstructure on the tensile strength and fatigue strength was analyzed. The results showed that the tensile strength of AZ31 B magnesium alloy CMT welded joint was212.9 MPa, and the fatigue strength 16.72 MPa of the joint under 2×106cycles was only 7.8% of its tensile strength,and the fatigue strength of the welded joint was much lower than that of their tensile strength.