Al-6Mg-0.9Mn-0.12Zr合金板材MIG焊接接头的显微组织和性能

Microstructure and properties of MIG welding joint of Al-6Mg-0.9Mn-0.12Zr alloy sheet

对一种4 mm厚Al-6Mg-0.9Mn-0.12Zr合金退火态板材进行MIG焊接,并研究焊接接头的显微组织、力学性能和耐腐蚀性能。结果表明,焊缝中心为枝晶组织,熔合线附近为柱状晶而且存在一层细晶组织,焊缝中的主要析出相为Al_(6)Mn。焊缝区和焊接热影响区的硬度均低于母材,焊缝中心硬度值最低为70.8~72.5 HV。焊接接头的抗拉强度为322 MPa,焊接强度系数为0.9,焊接性能良好。焊接接头的剥落腐蚀等级为PB级,晶间腐蚀值为4.6~4.7 mg/cm^(2),与母材耐蚀性能相当,具有良好的耐腐蚀性能。

The Al-6Mg-0.9Mn-0.12Zr alloy annealed sheet was welded by MIG welding,and the microstructure,mechanical prop⁃erties and corrosion resistance of the welded joint were studied.The results show that the center of the weld is dendrite structure,co⁃lumnar crystal near the fusion line and there is a layer of fine crystal structure.The main precipitated phase in the weld is Al6Mn.The hardness of the weld zone and heat affected zone is lower than that of the base metal,and the minimum hardness value of the weld cen⁃ter is 70.8~72.5HV.The tensile strength of the welded joint is 322 MPa,and the welding strength coefficient is 0.9%,with good welding performance.The exfoliation corrosion grade of the welded joint is PB grade,and the intergranular corrosion value is 4.6~4.7 mg/cm^(2),which is equivalent to the corrosion resistance of the base metal and has good corrosion resistance.