空心阴极真空电弧焊钛合金接头焊接特性

Welding Characteristics of Titanium Alloy Joints Welded by Hollow Cathode Vacuum Arc Welding

摘要:

采用空心阴极真空电弧技术焊接TC4钛合金，研究空心阴极真空电弧的伏安特性、发射光谱等物理特性，分析不同气体流量下焊缝的微观组织特征，测试焊缝的力学性能。结果表明：气体流量影响空心阴极真空电弧的物理特性，当气体流量降低时，电弧伏安特性曲线上升，电弧中心区域出现快电子主导的蓝色形态，电弧离子浓度增强；TC4钛合金母材的显微组织为（α+β）的两相组织；焊接热影响区的显微组织为等轴初生α+针状马氏体α′相组织与等轴初生α相+含针状马氏体α′相的转变β相组织的混合物，焊接热循环影响热影响区2种组织的分布；焊缝为针状马氏体α′组成网篮组织；随着气体流量的减小，焊接能量密度增加，马氏体晶粒粗化并且分布散乱；焊接接头的抗拉强度高于母材。

Abstract:

The microstructure of Ti-6Al-4V joints by hollow cathode vacuum arc welding with different gas flow rates was studied, and the tensile properties were investigated. The results show that the microstructure of base metal is a mixture of α phase and β phase. The microstructure of heat affected zone are equiaxed and primary α phase and needle martensite α′ phase dispersed in the transformed β phase. The distribution of two kinds of microstructures in the heat-affected area is affected by the welding thermal cycle. The microstructure of weld seam mainly consists of α′ martensite phase. The decrease in welding gas flow rate and the increase in welding energy density result in coarse and more scattered martensitic grains. The tensile strength of welded joint is higher than that of base metal.