2018 Volume 36 Issue 1 Pages 104-110
The research and development of nuclear fusion reactors are going on to acquire a next-generation energy source. The reduced activation ferritic/martensitic steel F82H is adopted as a structural material of the blanket module, which is the device set on the inner wall of fusion reactors. As welding for each thickness of F82H, the most suitable welding method will be selected. Laser beam welding is examined to adopt in thin part. However, by laser beam welding in the actual weld joints, weld defects should be considered. And performing post weld heat treatment (PWHT) is necessary because F82H is based on 9Cr-1Mo steel. Therefore, the objectives in this research are to clarify of laser beam welding condition for performing no defect weld joints and to be adequate PWHT condition. Appropriate laser beam welding condition of F82H is evaluated by cross-section observation in welds. As PWHT condition, heating time and heating temperature is selected by Vickers hardness and ductile brittle transition temperature (DBTT) from Charpy impact test. From cross-section observation in welds of F82H, some no defect weld joints are identified. 710°C∼730°C×1h was adequate in PWHT condition to reduce welds hardness to base metal hardness and to shift DBTT to sufficiently low level. Therefore, in this study, it is found that sound weld joints can be realized by selected the appropriate welding condition.