Mechanical and microstructural behavior in friction stir welds of copper and brass

The effect of friction stir welding on the microstructure and mechanical properties of copper and Cu-30Zn brass alloy was investigated by choosing fixed rotational speed of 950 rpm with welding travel speeds of 190 and 235 mm/min for both the copper and brass alloys. Microstructural investigations showed very fine grains with some deformed grains in the stirred zone and some coarser grains in the thermo-mechanically affected zone and base metal; whereas, no obvious HAZ was detected in welds. Results show that the grain size profile, hardness values and mechanical strength were not highly affected by the welding travel speed. In fact, the mechanical properties of both copper and brass should be determined as a result of mutual interaction between involving mechanisms. Depending on welding parameters, either they mitigate each other or some of them overcome the others and form a certain hardness or strength behavior in welds