Ti和Zr对铝合金冷金属过渡原位焊接性能的影响

Influence of Ti and Zr on cold metal transfer in-situ welding properties of aluminum alloy

在冷金属过渡(CMT)焊接5A66铝合金的基础上,分别添加Ti粉和Ti、Zr混合粉末进行原位合金化焊接,研究原位合金化焊接方法对焊接接头的影响。采用光学显微镜(OM)、扫描电镜(SEM)、能谱分析(EDS)、微区X射线(XRD)以及显微硬度和拉伸力学性能测试对不同工艺条件下的试样进行显微组织和力学性能分析。结果表明:Ti、Zr在液态熔池中与Al反应,生成细小的Al3Ti、Al3Zr粒子,提高焊缝区的显微硬度,但焊缝中气孔增多。熔合线附近靠母材侧存在等轴晶薄层,原位反应增加等轴晶薄层的宽度。新生成第二相颗粒的弥散强化作用提高焊缝区的力学性能。合金元素的添加对焊接接头热影响区的影响不大,由于实际热输入量很低,焊缝强度系数约为0.9。

In order to study the effect of in-situ alloying welding on aluminum alloy joint, the cold metal transfer （CMT） in-situ welding test with the addition of Ti, Ti and Zr mixed powder was carried out on 5A66 aluminum alloy. The microstructures and mechanical properties were investigated by OM, SEM, EDS, micro X-ray diffraction, microhardness test and tensile mechanical properties test. The results indicate that, small and uniformed A13Ti and AI3Zr particles form in the weld zone, which enhances the mechanical properties and phase distribution in this area, but this also increases the tendency of gas bubbles in the joint at the same time. There is also a grain zone along the fusion line, in-situ reaction increases the width of the grain zone. The dispersion of newly formed second phases enhances the mechanical properties of the weld seam. The alloy element addition does not affect the heat affected zone （HAZ）, the strength coefficient of joints fractured is about 0.9 because of the lower heat input of CMT method.