Influences of Quenching Temperature on the Microstructure Evolution and Strength−Toughness of a Novel Medium‐Carbon Ti−Mo‐Bearing Martensite Steel
Jisheng Guan, Qing Yuan, Qing Yuan, Qinpan Yuan, Qinpan Yuan, Lei Fan, Yuebiao Yang, Guang Xu
Abstract
The simultaneous improvement of strength and toughness in high‐strength steels is a challenging task. Herein, a novel medium‐carbon Ti−Mo‐bearing martensite steel is developed. The influences of quenching temperature on microstructure evolution and strength−toughness are investigated. Microstructure and precipitation analyses are conducted to clarify possible reasons for the improvement of strength−toughness in the as‐developed steel. After the addition of Ti and Mo, the martensite steel yields a high tensile strength of ≈1700 MPa and an impact energy of 43 J at –40 °C. The improved strength and toughness is attributed to better grain refinement strengthening and precipitation strengthening by combination of thermo−mechanical control process (TMCP) and quenching and tempering (Q−T) processes. Although no significant variation is observed in the strengths of Ti−Mo‐bearing martensite steels quenched at a temperature range of 850−910 °C, the impact energy of Ti−Mo‐bearing martensite steel obviously decreases at a higher quenching temperature of 910 °C. The decreased low‐temperature impact energy is caused by the coarsening of (Ti, Mo)C precipitates.