镁/钢异种合金激光深熔钎焊工艺特性

Welding characteristics of laser penetration welding-brazed Mg/steel dissimilar alloys

以AZ31镁合金和Q235钢为研究对象,采用激光深熔钎焊的方法进行工艺试验,获得了具有熔焊和钎焊双重性能的复合型接头.同时,利用光学显微镜、扫描电镜和拉伸试验机对焊接接头的微观组织和力学性能进行了研究.结果表明,在接头界面的上部,液态镁合金对碳钢产生部分溶蚀作用,导致碳钢微量熔化;在接头界面的中下部,未见碳钢的熔化,熔融的镁合金通过润湿和铺展作用,与碳钢形成了一钎合面.当激光束偏移量为0.6 mm时,接头成形良好,无裂纹、气孔等焊接缺陷,其抗拉强度高达182 MPa,约为镁合金母材的81%,且测试值波动也最小.

The experiments of laser penetration welding-brazed for magnesium alloy and steel were carried out with AZ31 magnesium alloy and Q235 steel as base metals,achieving a hybrid joint of welding and brazing.The microstructure and mechanical properties of butt joints were investigated by optical microscopy,scanning electron microscope and tensile testing.At the upper part of the joint,there is little melting or dissolving of steel due to high interface temperature.At the lower part of the joint,there is no indication of melted steel,the molten magnesium alloy,as filler metal,to form a successful joint of Mg/Fe dissimilar alloys by wetting and spreading.In particular,at 0.6mm laser offset,the average tensile strength could reach a maximum of 182 MPa,about 81% that of AZ31 Mg alloy.The fluctuation of tensile strength was the lowest in all laser offsets.