Investigation on Tempered Microstructure and Toughness of P92 Steel

Microstructure and toughness of P92 steel treated with different tempering temperature after being normalized at 1050 ℃ was studied by OM,SEM,XRD and impact test.The results show that normalized P92 steel consists of typical martensite lath,remaining austenite and M23C6 precipitates.Microstructure and toughness change slightly at relatively lower tempering temperature.The phenomena of martensite lath breaking,dissociation of remaining austenite and tempering brittleness are found between 500 ℃ and 600 ℃.With the increase of tempering temperature,the amount of sub-structure increases and blocky ferrite is also observed,resulting in the rapid increase of impact energy.