高强铝锂合金炉中钎焊及接头组织分析

Analysis on high strength Al-Li alloy joints brazed in furnace

采用CsF-AlF3钎剂和Ag-Al-Cu-Zn钎料,实现了高强铝锂合金的炉中钎焊。结果表明,在氮气保护的条件下,钎焊接头的抗拉强度最高可达到390MPa,强度系数接近0.89;抗剪强度最高可达到380MPa,强度系数约为0.86,均高于现有文献报道的高强铝锂合金的焊接接头强度系数值。对试验结果的理论分析表明,在530℃左右有效地去除铝锂合金表面的氧化膜是实现钎焊连接的关键,而氮气保护则是改善和提高钎缝力学性能的有效手段。

High strength Al-Li alloy was brazed in furnace by using Ag-Al-Cu-Zn filler metal with CsF-AlF3 flux. The results show that under the condition of N2 atmosphere, the tensile strength of butt joint is up to about 390 MPa with the strength factor of 0.89 and the shear strength of lap joint is up to about 380 MPa with the strength factor of 0.86, which all the strength factors are higher than those of fusion welding and brazed joints of high strength Al-Li alloy reported. The experimental results and theoretical analyses show that, effectively destroying and removing the complex oxide films on the surface of Al-Li alloy under the temperature of about 530℃ is the key factor to the brazing process and the protection of N2 is an important way to improve mechanical properties of the braze metal.