Thermo-mechanical evolution of Cu-Cr-Zr alloy joint fabricated by continuous driving friction welding

The thermocouple-bluetooth technology was employed to measure temperatures at feature points of Cu-Cr-Zr alloy joint fabricated by continuous drive friction welding. The relationship between temperature and microstructure evolution of welded joint was also investigated. The results show that every feature point demonstrated a certain temperature delay phenomenon. The highest temperature occurred in two-thirds radius area along the radial direction, and at friction interface along the axial direction, respectively. Meanwhile, the temperature in rotary workpiece was lower than that in moving workpiece. Due to the effect of thermo-mechanical coupling, fine equiaxed grains formed in the weld nugget zone while the grains in thermal-mechanical affected zone (TMAZ) were elongated with obvious plastic flow. From axis to outside diameter, both the width of dynamic recrystallization area and grain size increased while the trend of radial plastic flow in adjacent TMAZ decreased. In addition, compared with rotary workpiece, grains in the weld zone of HJ1.55mmmoving workpiece became coarsened due to higher temperature and longer duration over recrystallization temperature.