添加不同合金粉末激光熔钎焊铝/钢异种金属接头的组织与性能

Structure and Property of Aluminum-Steel Dissimilar Metal Joint by Laser Fusion Brazing with Addition of Different Alloy Powders

预涂分别富含硅、镁、锰、硼、锌元素的五种合金粉后,对不等厚5A06铝合金板和ST04Z镀锌钢板进行了激光熔钎对接焊,研究了焊接接头的显微组织、拉伸性能和耐腐蚀性能。结果表明:接头界面处形成了金属间化合物层,近镀锌钢侧形成的金属间化合物主要为Fe_2Al_5,近铝合金侧形成的主要为FeAl_3,预涂富含硼的合金粉得到的金属间化合物层最厚;接头均在焊缝处发生以韧性断裂为主,脆性断裂为辅的混合断裂,预涂富含硅的合金粉得到的接头的抗拉强度最大;预涂富含锰的合金粉焊接后,接头的耐腐蚀性能最好,预涂富含镁、硅、锌的合金粉焊接后,耐腐蚀性能依次降低,腐蚀易发生在金属间化合物层与铝合金界面处。

5 A06 aluminum alloy and ST04 Zgalvanized steel plates with different thicknesses were joined by laser fusion brazing after precoating with five alloy powders enriched with Si, Mg, Mn,B,Zn elements,respectively.The microstructure,tensile properties and corrosion resistance of the welded joint were studied.The results show that an intermetallic compound layer was formed at the interface of the joint;the intermetallic compound formed near the galvanized steel side was mainly composed of Fe2Al5 and near the aluminum alloy side was mainly composed of FeAl3.The intermetallic compound layer obtianed by precoating with B-rich alloy powder was the thickest.All the joints fractured at the weld in a mixed mode that was dominated by ductile fracture and supplemented by brittle fracture.The tensile strength of the joint obtained by precoating Si-rich alloy powder was the largest.The corrosion resistance of the joint was the best after welded by precoating with Mn-rich alloy powder,and decreased when precoating with Mg-rich,Si-rich,and Zn-rich alloy powders in turn.The corrosion was likely to occur at the interface between intermetallic compound layer and alumium alloy.