Study on PWHT improving toughness at IRCGHAZ of WB36 steel

This study is concerned with the effect of post welding heat treatment(PWHT)on the microstructure and properties at the intercritical reheated coarse-grained heat-affected zone (IRCGHAZ)of WB36 steel, and investigated whether the PWHT could reduce IRCGHAZ embrittlement.The results showed that the hardness at IRCGHAZ has little change, but the toughness exhibited significance increase after PWHT at the temperature of 590℃ for 2 h, with the Charpy impact toughness increasing 85 percent comparing with the as welded IRCGHAZ.Fractographs of IRCGHAZ is found to be changed from the mixed fractographs of quasi-cleavage facets and microvoids to purely microvoids after PWHT.Enhancement of toughness at IRCGHAZ is caused by the decomposition ofMA constituents at the lath martensite boundaries occurred during the PWHT, and lath martensite in the matrix of IRCGHAZ is showed little change, which have little influence on the toughness.