Friction welding of UFG copper using the W2Mi prototype machine

Abstract

When welding ultra-fine-grained metals using conventional methods, the microstructure in the joint area is degraded (mainly due to recrystallization) in the heat-affected zone and a significant deterioration of mechanical properties, including joint strength. The aim of the research presented in this article was to identify the possibility of obtaining joints with strength close to initial material using friction welding of metal materials with ultra-fine grain. For this purpose, UFG (ultra-fine-grained) material was produced from technically pure M1Ez4 copper using a hybrid SPD (severe plastic deformation) process. The welding process was carried out on a machine with a prototype design that allows minimizing the welding time, while generating high force. The process parameters used on the prototype machine resulted in an increase in the hardness of the material by 4% in the joint area. The strength of the joint compared to the base material decreased slightly by 2%. The tests carried out proved that, using appropriate process parameters, it is possible to obtain a UFG metal joint without a decrease in its mechanical strength.