焊丝成分对铝/钢电弧辅助激光熔钎焊接头组织及力学性能的影响

Effect of Filler Wire Composition on Microstructure and Mechanical Property of the Aluminum/Steel Arc Assisted Laser Welding-Brazing Joint

采用电弧辅助激光熔钎焊方法实现了铝合金与镀锌钢的对接焊,并在焊接过程中通过填充Al-Mg、Al-Cu及Al-Si焊丝对接头的焊缝及界面进行微观组织调控。采用扫描电子显微镜(Scanning electron microscope,SEM)、电子探针(Electron probe micro analyzer,EPMA)对填充不同焊丝的焊缝及Al/Fe界面处的微观组织进行了观察与物相分析,对接头进行了拉伸力学性能测试,并讨论了界面金属间化合物形成及其对接头断裂性能的影响。结果表明:填充Al-Mg、Al-Cu焊丝的接头在界面处生成了Fe_(2)Al_(5)和Fe_(4)Al_(13)两种金属间化合物,而填充Al-Si焊丝时界面处生成了Al_(8)Fe_(2)Si和Fe_(4)Al_(13)。填充Al-Si焊丝的接头可获得最大抗拉强度176 MPa,接头断裂在拉伸应力-应变曲线的塑性变形阶段。界面金属间化合物厚度并非影响接头失效的决定性因素,而Fe_(2)Al_(5)自身裂纹和界面处不同相的晶格匹配决定了接头的力学性能。

The aluminum alloy and the galvanized steel were joined by arc assisted laser welding-brazing method in a butt configuration.The microstructures of weld and interfacial were controlled by filling Al-Mg,Al-Cu and Al-Si filler wire during welding process.The scanning electron microscope and the electron probe micro analyzer were used to observe the microstructure and identify the phases,the tensile strength of weld joint was tested,and the formation of interfacial intermetallic compound(IMC)and its effects on weld joint fracture were discussed.The results show that two types IMC of Fe_(2)Al_(5) and Fe_(4)Al_(13) are formed at interface for filling Al-Mg and Al-Cu filler wires,while the Al_(8)Fe_(2)Si and Fe_(4)Al_(13) are formed at interface when filled the Al-Si filler wire.The highest tensile strength of 176 MPa can be obtained when filled the Al-Si filler wire,and the fracture of the joint is in the plastic deformation stage of the tensile stress-strain curve.Interfacial IMC thickness is not the determining factor to inf-luence the failure of weld joint,while the crack in Fe_(2)Al_(5) phase and the lattice matching of different phases at interface determine the mechanical property of weld joint.