5754铝合金/镀锌钢CMT焊接接头微观组织和力学性能的研究

Study on the microstructure and mechanical prope-rties of 5754 aluminum alloy/galvanized steel CMT welded joint

分别选用ER4043焊丝和ER4047焊丝,采用CMT焊对AA5754铝合金板和DC56+Z50镀锌钢板异种材料进行焊接,通过拉伸、弯曲、疲劳以及金相分析等试验对铝/钢焊接接头力学性能与显微组织进行了研究。结果表明:在CMT电流模式下,采用ER4043焊丝和ER4047焊丝均能得到成形良好的焊接件。拉伸断裂在铝侧焊缝,同时生成的金属化合物层厚小于10μm,主要是Fe_(2)Al_(5)和FeAl_(3)。焊接电流为60 A,采用ER4043焊丝的焊接接头抗拉性能较为理想,在焊缝处均没有出现裂纹,铝/钢搭接接头的断裂位置在铝侧焊缝处,但是接头疲劳性能存在较大的波动,接头的疲劳寿命达到10^(7)次时加载应力仅为63 MPa。

ER4043 welding wire and ER4047 welding wire are selected respectively,and CMT welding is used to weld dissimilar materials of AA5754 aluminum alloy plate and DC56+Z50 galvanized steel plate.The mechanical properties and microstructure of aluminum/steel welded joints are studied by tensile,bending,fatigue and metallographic analysis.The results show that both ER4043 welding wire and ER4047 welding wire can get well-formed weldments in CMT current mode.Tensile fracture occurs in weld on the side of aluminum,the thickness of intermetallic compound layer is less than 10μm,mainly Fe_(2)Al_(5) and FeAl_(3).When using ER4043 welding wire with 60 A welding current,the tensile property of welded joint is ideal,and there is no crack in the welds.The fracture of the aluminum/steel lap joint occurs in weld on the side of aluminum.However,the fatigue property of joint fluctuates greatly,and the loading stress is only 63 MPa when fatigue life reaches 107 times.