||EVALUATIONION OF COLD CRACK SUSCEPTIBILITY IN MULTIPASS WELDS OF REDUCED ACTIVATION FERRITIC／MARTENSITIC STEEL F82H BASED ON NUMERICAL SIMULATION OF HYDROGEN DISTRIBUTION IN WELDS
Kawauchi, K. ,
Hatoya, K. ,
加藤, 太一朗 ,
廣瀬, 貴規 ,
谷川, 博康Mori, H.
Multi-pass welding will be adopted to join thick plates of reduced activation ferritic/martensitic steel F82H, to construct the blanket modules set on the inner wall of fusion reactors. Especially, in the case of multi-pass welding for thick plates of F82H, cold cracking should be considered, because of hardened zone formed by martensitic transformation in the welds. Therefore, the crack susceptibility in welds of F82H was investigated using a constant strain rate tensile (CSRT) test and numerical analysis of hydrogen distributions in the welds.Figure 1 shows the criteria of cold cracking due to hydrogen embrittlement, which means the relation between hydrogen contents in weld metal and fracture strength measured by CSRT test for hydrogen charged specimens. Based on the results, when the value of fracture strength plus 63.4 times of hydrogen content is less than 1740, cold cracking owing to hydrogen embrittlement is suppressed in weld metal. Hydrogen distributions calculated using the developed simulation code based on activity considering hardness and stress , are demonstrated in Fig. 2. In the case of without preheat and PWHT, hydrogen was concentrated at the bond region, which means around the border between weld metal and HAZ. In contrast, hydrogen content at the bond in multi-pass welds with preheated and PWHT was lower than the non-treated one. As it is, in this case, calculation indicated that the occurrence of cold cracking was negative even though preheating and PWHT had not been conducted to the multi-pass welds. Because the value of tensile stress plus 63.4 times of hydrogen content was less than the critical value in this study.
18th International Conference on Fusion Reactor Materials