Mechanical and microstructural characterization for HIPed joints of CLF-1 steel with different surface roughness

Reduced-activation ferritic/martensitic steels (RAFMs) such as CLF-1 steel, have been developed as candidate structural materials for breeding blanket in fusion reactors. Hot isostatic pressing (HIP) diffusion method is expected to provide the most promising method to solve the problem to join cooling rectangular channels with thin panels during fabrication of the first wall in breeding blankets. Mechanical and microstructural characterization of HIPed joints of CLF-1 steel with four typical surface roughness has been investigated. The results indicate that with the increase of surface roughness, the tensile properties are similar to as-received CLF-1 steel, the elongation and the area reduction decreased, the impact energy decreased sharply. The HIPed joints are very sensitive to the bonding surface states, the roughness could influence degassing, oxide and cavities formation, diffusion efficiency of bonding surface, and reduce the roughness, efficient degassing and elimination of oxide formation of the HIP joint surfaces is important to obtain a satisfactory joint.