According to the analysis on 90 mm x 90 mm 1Cr11Ni2W2MoV steel with 540 MPa endurance rupture time less than 100 h produced by vacuum induction furnace smelting + electroslag remelting (Φ600 mm ingot) + forging material process

it is found that insufficient tempered martensite content in the microstructure and uneven carbide precipitation in the martensite lath are the reasons for the low strength and toughness of the steel

which leads to the durability and fracture time of less than 100 h. By decreasing the heating temperature of forging bloom from 1 130-1 150 °C to 1 000-1 020 °C

and changing forging method for 90 mm x 90 mm steel bar from once heating-forging to double heating-foring to ensure the end forging temperature >900 °C

and decreasing the tempering temperature of the durability test specimen from 660-680 °C to 600-620 °C

the fracture time of 540 MPa durability of 1Cr11Ni2W2MoV steel is increased from 36-37 h to 146-148 h.