Effect of Intercritical Austenitizing Temperature during Quenching–Intercritical Quenching–Tempering Process on Toughness of 25Mn2Si2Cr Bainitic Steel

Abstract

An intercritical quenching process is introduced between conventional water quenching and tempering to 25Mn2Si2Cr bainitic steel. The study suggests that the quenching–intercritical quenching–tempering (Q–IQ–T) process effectively improves mechanical properties compared with conventional air cooling and tempering (Q–T). When the intercritical austenitizing temperature is 860 °C, as‐treated steel's tensile strength, yield strength, impact energy (U‐notch) is 1453 MPa, 1141 MPa, and 99 J cm−2, respectively, which is enhancement of 5.4%, 3.2%, and 20.7% compared with the conventional Q–T process. The increase of toughness is achieved without compromising strength. The improvement of toughness arises from refinement of grain size and microstructure.