Effect of Heat Treatment on Microstructure and Properties of Quenched and Tempered Steel with High Vanadium Contents

After heat treatment, the microstructure of quenched and tempered (Q&T) steel with high vanadium (V) content was characterized using metallographic and scanning electron microscopes (SEM). The proto-austenite grains of the tested steel were compared at different quenching temperatures, and the precipitation behavior of precipitates and matrix microstructure characteristics at various tempering temperatures were studied. Tensile properties and low-temperature impact toughness of the tested steel with different heat treatments were measured using an electronic universal testing machine and an impact testing machine. The findings indicate that as the quenching temperature increases, the size of the proto-austenite grains gradually increases. When the quenching temperature surpasses 920 °C, the size of the proto-austenite grains obviously increases. With a constant tempering temperature, an increase in quenching temperature results in a decrease in the size of precipitates. With a constant quenching temperature, an increase in tempering temperature results in an increase in the size of precipitates. Therefore, the tested steel quenched at 920 °C for 1 hour and then tempered at 630 °C for 1.5 hours would obtain excellent comprehensive mechanical properties, with a tensile strength of 1233 MPa and a low-temperature impact value of 64 J.