Realising equal-strength welding with good conductivity in Cu–Cr–Zr alloy via friction stir welding

Abstract

Realising high-quality welding of the peak aged Cu–Cr–Zr alloy has always been a big challenge. Under a low rotation rate of 400 rev min⁻¹, equiaxed ultrafine grains together with nanoscale precipitates with comparable size to that of the peak aged state were obtained in the nugget zone of the friction stir welded joint. Further, the initial strengthened precipitates were also preserved near the nugget zone, neither dissolved nor coarsened. Therefore, softening zone disappeared and a high-quality weld with equal strength to the base material was first achieved. Furthermore, the electrical conductivity of the joint was hardly weakened. This study provides an effective method to improve the strength and electrical conductivity of the precipitation-hardened Cu alloy joints.