Hot Isostatic Pressing Diffusion Bonding and Interface Residual Stress Analysis of CuCr1Zr Alloy and 25Cr2Ni4MoV Steel

A circular sleeve composed of CuCr1Zr alloy and 25Cr2Ni4MoV steel was effectively joined using the hot isostatic pressing (HIP) diffusion bonding technique. The interface diffusion zone of the joint underwent metallographic analysis utilizing a field-emission scanning electron microscope (FE-SEM). The findings indicated a robust bonding at the interface between the copper and steel sleeve components, devoid of any microcracks. EDS analysis reveals that the solid solution at the diffusion interface primarily consists of Cu, Cr, Fe, Ni, and C elements. Adequate diffusion transforms the mechanically interlocked interface into a metallurgical bonding interface, significantly enhancing the bonding strength and hardness of the CuCr1Zr alloy-25Cr2Ni4MoV steel bimetallic interface. Tensile testing results demonstrate that the average tensile strength of the copper matrix in the HIP diffusion-bonded assembly is 343 MPa. Fracture within the copper matrix indicates that the bonding strength at the interface exceeds this value. Additionally, the finite element method was employed to assess thermally induced stresses and strains in the CuCr1Zr alloy-25Cr2Ni4MoV steel HIP joint. The outcomes revealed that the peak equivalent residual stress within the entire joint was situated in the vicinity of the 25Cr2Ni4MoV steel, near the interface adjoining the inner wall. Simultaneously, the CuCr1Zr alloy substrate alleviated residual stress by undergoing plastic deformation.