脉冲大电流扩散焊接Al-Li合金1420

Diffusion welding of Al-Li alloys 1420 with pulsed current

摘要: 采用脉冲大电流热加工技术焊接Al-Li合金1420。通过比较不同焊接工艺下的焊接产品,在最优焊接条件下获得了接头抗拉强度为母材强度75%的焊接接头。分析了接头微观结构及其对接头性能的影响,通过金相图片和扫描图片分析了接头处焊接点的形成过程,认为焊接过程实际可以分为由于微区熔化现象引起的焊接点高速形成阶段和围绕焊接点的原子扩散过程。脉冲大电流焊接过程由于焊接时间短,因而晶粒并没有发生二次生长。接头断口SEM照片显示,接头断裂方式为沿晶/穿晶混合断裂方式。

Abstract: Pulsed current heating technology was used to weld the 1420 Al-Li alloy.Samples welded with different conditions were compared.The best tensile strength of joints is 75% of the base metal.The influence of microstructure on properties of joints was analyzed.The welding process was analyzed by SEM images and micrograph pictures.Joined points occurred with a higher speed in the first step for micro-melting in the interface and a lower speed in the second step for atom diffusion.The grain size in the joints keeps steadily because of a shorter diffusion time.The fracture of the joints is a mixture of intergranular cracking and transgranular cracking.