黄铜辅助镁合金/不锈钢TIG熔钎焊研究

Study on Brass Auxiliary TIG Welding-brazing of Magnesium Alloy and Stainless Steel

以0.3 mm厚的H62黄铜片为中间层,采用TIG焊的方法对AZ31B镁合金和304不锈钢板材进行搭接熔钎焊,观察分析了熔钎焊接头的宏观形貌及显微组织,测定了元素分布及力学性能。结果表明,在交流电流70 A、焊接速度100 mm/min的条件下,实现了镁合金和不锈钢的TIG熔钎焊。接头由焊缝区、钎缝区和熔合区三部分组成,钎缝区不锈钢一侧发生了不规则溶解,钎缝区显微组织由α-Fe、α-Mg及沿α-Mg晶界分布的少量的Mg-Cu-Al共晶体组成。熔钎焊接头的拉伸断裂发生在焊缝区,抗拉强度达到130 MPa。钎缝区钢一侧形成的不规则嵌入式组织结构明显提高了不锈钢与镁合金的界面的结合强度。

The lap welding-brazing of AZ31B magnesium alloy and 304 stainless steel plates was carried out by TIG welding with 0.3 mm H62 brass sheet as interlayer. The macroscopic morphology and microstructure of welding-brazing joint were observed and analyzed, and the distribution of elements and mechanical properties were tested. The results shows that the magnesium alloy can be joined with the stainless steel by TIG welding-brazing with alternating current of 70 A and welding speed of 100 mm/min. The joint consists of weld zone, brazing seam and fusion zone. The irregular dissolution occurs at the side of stainless steel in brazing seam. The microstructure of brazing seam consists of α-Fe, α-Mg and a small amount of Mg-Cu-AI eutectic distributed along α-Mg grain boundary. The tensile fracture of welding-brazing joint occurs in weld zone, and the tensile strength is 130 MPa. The irregular embedded structure formed at the side of stainless steel in brazing seam significantly improves the bonding strength of interface between stainless steel and magnesium alloy.