The oxidation and stress corrosion cracking (SCC) behaviors of Alloy 52M buttering (52Mb) layer were studied in simulated pressurized water reactor (PWR) primary water after microstructure characterization. The 52Mb layer was first post-weld heat treatment (1st-PWHT) and follow-up PWHT (FU-PWHT). Two dilution zones (DZs) were found in both the 1st-PWHT and FU-PWHT 52Mb samples. FU-PWHT decreased the Cr content in the first dilution zone, enhancing the oxidation rate and accelerating the formation of the local oxidation penetration zone at the oxide/substrate interface. Lower Cr content and high Fe content in the dilution zone were detrimental to the SCC resistance of the 52Mb in PWR primary water.