Fracture toughness distribution of a thick plate of A533B with welding

Ha, Yoosung  ; Shimodaira, Masaki ; Katsuyama, Jinya  

In Japanese surveillance program for RPV, the specimens are taken from base metal of a quarter thickness in a plate, weld metal and heat affected zone (HAZ) as representative materials. JEAC4201 specifies Embrittlement Trend Curve (ETC) for base metal but not for HAZ, because the fracture toughness of HAZ is considered to be generally better than that of base metal. However, since the microstructures in HAZ are inhomogeneous due to multi-pass welding, it is necessary to investigate the fracture toughness of HAZ with more specific basis. The Charpy impact properties and fracture toughness (T and T) derived from three representative positions in HAZ were compared with those of base metal. T and T of HAZ were lower than those of base metal, meanwhile the results of Charpy impact test and fracture toughness test for HAZ indicated a relatively large scatter.