Dissimilar joints between steel and copper alloys are widely used in aerospace, mechanical, electrical, metallurgical and refrigeration industries because of their high strength and thermal conductivity, good mechanical properties and electrical conductivity, high corrosion resistance and low cost.
It is difficult to weld steel and copper alloys because the physical properties such as their melting points, coefficients of heat conductivity and coefficients of thermal expansion are different. It is particularly difficult to weld brass to other metal because evaporation of zinc during welding makes the weld porous.
To get a sound weld of brass, it is necessary to keep the heat input as low as possible. Then, it helps formation of a small heat affected zone (HAZ) in the weld and helps protect the welding zone against the surrounding medium. Another method used to limit the heat input into the welding pool in the welding of brass materials is to use filler materials. When these are used, the arc is concentrated on the filler material, which reduces Zn loss from the brass to be welded.
Taking it into consideration, Kim Tae Hong, a section head at the Faculty of Material Science and Technology, performed butt braze welding of brass tube to steel plate using TIG welding by selecting appropriate welding currents and arc positions, and evaluated the characteristics of the joints.
No pore was found in the joint at the welding current of 70A and different arc offset, and no crack was found in the joint after 300 times of thermal cycle. In addition, a sound joint was formed without evaporation of zinc when the arc position was inclined towards the side of steel.
You can find more information in his paper “Study on the TIG Welding of Brass to Steel” in “Proceedings of KUTIC-2025”.