Research On A-TIG Welding Of Cu-Cr-Zr Alloy

Cu-Cr-Zr alloy is currently widely used in high strength, high conductivity field. Remarkable achievement has been made in the development and application of Cu-Cr-Zr alloy. TIG welding is one of the most common method of welding. But due to the shallow penetration of single channel, the deposit rate is low, which limits its application. In this study, A-TIG (Activating flux TIG) welding as one high efficient welding process is introduced to the welding of Cu-Cr-Zr alloy.There are four parts in this study of A-TIG in Cu-Cr-Zr alloy. Firstly, four compounds are chosen out of eleven, which can increase penetration and modify the welding shape .Secondly, using the formula of uniform design method to obtain the optimized formula, which is composed by the four compounds. Thirdly, welding the thick sheets by A-TIG which fluxes is the optimized formula without welding wires. At last, studying the mechanism on increasing penetration by high-speed photography.When using single composition fluxes, oxide and fluoride compounds benefit to increase the welding penetration, but chloride has no contribution. The penetration of joint coating with SiO2 can reach twice more than the common TIG. Welding 9mm sheets, the optimized formula can increase penetration significantly , which can rich 2.8 times. Welding the thin sheets with thickness of 3mm, we use currents of 100A,120A,140A in A-TIG, and 160A in TIG . We find that The grain crystal of the joint grow seriously. The electro-conductibility and the micro-hardness decreases in different degrees. The current of 160A in TIG is equivalent to the current of 120A. And as the currents reduce, the grain crystal size becomes small. At the same time, the electro-conductibility and the micro-hardness increases. The high-speed photography pictures show that the oxide has obvious influence on arc contraction. On the contrary, the fluoride and the chloride influence slightly. The mechanism of the optimized formula on the penetration increment is very complex. The heat of the arc concentrates and the temperature of the arc increases. The arc pressure increases remarkably. And then, the penetration in A-TIG increases.