Analysis of stress distribution characteristics of Zr/Ni circumferential electron beam welded joints

Zirconium has good mechanical properties, compatibility with nuclear fuel and radiation resistance, is widely used in the nuclear industry. Nickel has good mechanical properties and corrosion resistance, and is often used as a structural material. There are large differences in thermophysical properties and poor metallurgical compatibility between zirconium/nickel. There is currently no research on fusion welding of zirconium/nickel. In direct welding, the electron beam welded joint is composed of (γ-Ni+Ni₅Zr) eutectic+Ni₅Zr dendrite composite structure, which leads to welding cracks under residual stress. The tensile strength is only 36.4 MPa. In beam offset welding, the tensile strength of the joint increased to 189 MPa. The finite element simulation research on the stress field and temperature field of the joints under different welding parameters, combined with theoretical calculations, revealed that due to the structure of the weld, there is reheating phenomenon in the initial stage of welding, resulting in high residual stress. Electron beam deflects to Ni side effectively reduces the residual stress and thermal stress of the joint, which is the main reason for the disappearance of cracks.