Microstructure and Properties of Friction Stir Welding Joint of Cu-Cr-Zr Alloy

Cu-Cr-Zr alloy plate with a thickness of 4 mm was welded by using friction stir welding（FSW）. After FSW,aging treatment of the joint was carried out. The effect of FSW and aging treatment on the microstructure, mechanical properties and electrical conductivity of the welded joint was studied respectively. The results show that compared with those of base metal, the microhardness and conductivity of nugget zone of the FSW joint are significantly reduced. The main reason is that in the process of FSW, the violent stirring effect of stirring needle causes serious plastic deformation of the material and a lot of heat, the precipitation phase Cr particles are dissolved, and the precipitation strengthening effect is seriously weakened.Compared with those of the FSW joint, the microhardness and electrical conductivity of the joint after aging treatment are significantly increased. The reason is that the Cr particles dissolved in Cu matrix re-precipitate and evenly distribute in the Cu substrate, the precipitation strengthening effect is obviously enhanced, and the scattering probability of electrons decreases.