铝合金6082和5083 MIG焊接头的微观组织和性能

对高速列车车体常用铝合金6082与5083板材进行熔化极氩弧焊(MIG)对接,利用光学显微镜和扫描电镜分析异种材料焊接接头的显微组织特点,利用显微硬度计、拉伸试验机和电化学工作站对接头的力学性能和耐腐蚀性能进行测试和分析。研究结果表明,焊缝成型良好,焊缝区由细小的胞状树枝晶和等轴晶构成,熔合线附近为粗大的柱状晶;焊接接头抗拉强度为199.92 MPa,断后伸长率为5.18%,断裂位置在铝合金6082的焊接热影响区(HAZ),为韧性断裂,接头的正弯性能较差,背弯性能良好;铝合金5083侧的热影响区宽为4mm,6082侧的热影响区宽为15mm,接头两侧的硬度分布有明显差别,在6082侧距焊缝中心12.5mm的显微硬度最低为63HV;6082-5083异种铝合金焊缝的耐蚀性能优于母材5083,但比母材6082差。

Microstructure and Properties of MIG Welding Joint of Aluminum Alloy 6082 and 5083

Butt joint of dissimilar aluminum alloys 6082 and 5083 was prepared by metal inert gas arc welding (MIG).The microstructure,mechanical properties and corrosion resistance of welding joint were investigated using metallographic analysis,scanning electron microscopy,microhardness tester,tensile testing machine and electroche-mical workstation.The results demonstrated that the welding bead was well formed.The weld bead was composed of cystiform-dendritic and small axial grains and the coarse columnar grains mainly exited near the fusion line.The tensile strength and elongation of the joint were 199.92 MPa and 5.18%,respectively.The fracture occurred in heat affected zone (HAZ)of aluminum alloy 6082,which belonged to ductile fracture.The front bending property of the joints were poor.But the back bending property of the joints were good.The hardness distribution of the joints at 6082 and 5083 sides were different.The HAZ width of aluminum alloy 5083 and 6082 were about 4 mm and 15 mm,respective-ly.The lowest hardness in the 6082 side was 63HV.The corrosion resistance of dissimilar aluminum alloy 6082 and 5083 joint was better than that of the base metal 5083 but worse than that of the base metal 6082.