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以Sn-Zn钎料对变形镁合金AZ31B进行了炉中钎焊,研究了变形镁合金AZ31B钎焊接头的微观结构与连接强度。采用XRD、SEM、EDS等仪器分析了钎焊接头的界面组织和钎缝物相,测试了钎焊接头的剪切强度与钎缝组织的显微硬度。结果表明,Sn-Zn钎料在钎焊过程中与母材AZ31B发生溶解与扩散作用,在钎缝中生成金属间化合物Mg2Sn和(β-Sn+Mg2Sn)共晶组织。钎焊接头中母材的显微硬度最低,Mg2Sn的显微硬度最高,钎焊搭接接头平均抗剪切强度达到48 MPa。钎焊搭接接头的主要断裂形式为沿晶脆性断裂,断裂主要发生在共晶组织和Mg2Sn相处。
The as-brazed AZ31B magnesium alloy was brazed with Sn-Zn solder, and the microstructure and bonding strength of the AZ31B brazed joint were studied. The interface structure and braze phase of the brazing joint were analyzed by XRD, SEM and EDS. The shear strength of the brazing joint and the microhardness of the brazing joint were tested. The results show that the Sn-Zn filler metal dissolves and diffuses with the base metal AZ31B during the brazing process, and the intermetallic compounds Mg2Sn and (β-Sn + Mg2Sn) eutectic structure are formed in the brazing seam. The microhardness of the base metal in the brazed joint is the lowest, the microhardness of the Mg2Sn is the highest, and the average shear strength of the brazed lap joint reaches 48 MPa. The main fracture form of brazed lap joint is brittle fracture along the crystal. The fracture mainly occurs when eutectic structure and Mg2Sn phase.