Effect of a Thermal Welding Cycle on the Properties of a Reactor Vessel Shell
摘要
Abstract—The structure, hardness, and ductile–brittle transition temperature (DBTT determined on small Charpy specimens) of the heat-affected zone (HAZ) of two standard welded joints of a VVER reactor vessel made of 15Kh2NMFA-A steel with different nickel contents (1.34 and 1.46 wt %) are studied. Two (high- and low-hardness) subzones are distinguished in the HAZ. The DBTT of the high-hardness subzone is shown to be 60–70°C lower than that of the base metal, which is caused by the formation of martensite and lower bainite structures and grain refinement. The DBTT of the low-hardness subzone is 20–30°C lower than that of the base metal, which is explained by a lower density of carbides in this zone.