In-situ observation of phase transformation during rapid cooling processes

Yamada, Tomonori; Yonemoto, Yukihiro; Yamashita, Susumu   ; Muramatsu, Toshiharu; Komizo, Yuichi*

It is known that residual stress is important to keep the structural integrity. Laser welding is effective for the residual stress decrease because heat input is smaller and heats have a very small effect. Therefore, the repairing technology by laser welding has draw wide attention for a life extension of FBRs (Fast Breeder Reactors). To establish the laser repair technology, special attentions should be paid to the morphological developments. In the present work, morphological developments were directly observed using laser scanning conforcal microscopy during laser weld cooling.