Effects of Heat Treatment Process on Microstructure of 10Ni5CrMoV Steel

The 10Ni5CrMoV steel was quenched at different temperature. The austenite grain size was measured, and the relationship between grain size and temperature was determined. The results show that: grains of 10Ni5CrMoV steel grow evidently when the temperature of first quenching is above 1200 ℃; obvious microstructure heredity occurs when specimens are secondary-quenched above Ac3. Microstructure heredity disappears gradually while the temperature of secondary quenching increases. Microstructure heredity begins to disappear at 810 ℃; the recrystallization and finer grains appear and microstructure heredity disappears completely at 960 ℃. Fine austenite grains grow again at 970 ℃. Metallographic structure and grain size is adjusted by secondary quenching, which gets good obdurability and meets the requirement.