Correlation between magnetic hysteresis Properties and Vickers hardness in cladded reactor pressure vessel steel

We investigated the microstructure, magnetic hysteresis properties, and micro ︲ Vickers hardness of nuclear reactor pressure vessel （ RPV ） steel cladded with austenitic stainless steel. Characterization of the crystalline structure by electron backscatter diffrac tion revealed the existence of a delta ferrite phase in the austenitic cladding, and the formation of coarse and fine grain microstruc - tures in the heat affected zone （ HAZ ） of the RPV steel. The block specimen was cut into small pieces and magnetic hysteresis loops were measured with a vibrating sample magnetometer. Although the saturation magnetization of the RPV steel was constant, the coercivity in the HAZ region decreased gradually as a function of distance from the weld fusion boundary. A linear correlation was confirmed between the coercivity and hardness. This study demonstrates the feasibility of a magnetic evaluation of hardness and microstructures in RPV steel. ［ doi:10 . 2320 / jinstmet.JAW201702 ］