Microstructures and mechanical properties of friction stir welded dissimilar copper/brass joints

In this study, an experimental investigation has been carried out on microstructure and mechanical properties of friction stir welded copper/brass dissimilar joints. Effect of axial tool force to welding quality has been investigated under obtained optimal tool rotation rate and tool traverse speed conditions. The tool for the dissimilar copper/brass friction stir welding manufactured from X155CrMo-V12-1 cold work tool steel with material number of 1.2379. The friction stir welding quality was investigated by welding surface inspections, microstructural studies, micro hardness measurements and tensile tests. The experimental studies have shown that constant axial tool force during pre-heating and during welding process are very important. As a result, by using 2.5-3 kN of axial tool force during pre-heating and 5.5 kN of axial tool force during welding process, copper/brass dissimilar joints with well appearance and higher mechanical strength can be obtained.