Fatigue-resistant load-bearing steel for wind turbine main shaft, and manufacturing method and use thereof

A manufacturing method of a fatigue-resistant load-bearing steel for a wind turbine main shaft, comprising the following steps:

• step S1, smelting:
• smelting a raw steel into a first molten iron, followed by impurity removal and deoxidation, and adjusting contents of respective components to obtain a casting molten steel, wherein the casting molten steel comprises the following respective components in the following contents:
• Al:
• 0.12% to 0.15%, Si:
• 0.35% to 0.60%, Cr:
• 1.62% to 2.35%, V:
• 0.15% to 0.21%, Ti:
• 0.78% to 1.21%, Nb:
• 0.27% to 0.32%, C:
• 0.15% to 0.20%, Ni:
• 0.39% to 0.48%, Mn:
• 0.18% to 0.23%, and Fe:
• the balance;
• step S2, continuous casting:
• crystallizing the casting molten steel with an electric pulse, followed by solidification to obtain a continuous casting billet;
• step S3, rolling:
• subjecting the continuous casting billet to rough rolling and finish rolling sequentially to obtain a finish-rolled billet;
• and
• step S4, post-rolling treatment:
• cooling and then air-cooling the finish-rolled billet to obtain the fatigue-resistant load-bearing steel,
• wherein the continuous casting in the step S2 comprises transferring the casting molten steel to a continuous casting machine with a casting speed being set to 0.52 m/min to 0.64 m/min and a casting starting temperature being set to 1,520° C. to 1,535° C., and turning on an electric pulse transmitter with parameters being set as follows:
• a voltage:
• 2,500 V to 2,600 V, a frequency:
• 0.80 Hz to 0.88 Hz, and a capacitance:
• 180 μF to 200 μF, so as to obtain the continuous casting billet after the solidification;
• the rolling in the step S3 comprises:
• step S3.1, introducing the continuous casting billet into a rough rolling mill for the rough rolling, so as to obtain a rough-rolled billet, wherein the rough rolling comprises transverse rolling in two transverse rolling passes with reductions of 25% to 28% and 20% to 22% respectively, and longitudinal rolling in two longitudinal rolling passes with reductions of 16% to 19% and 13% to 15% respectively, and the transverse rolling is performed at a first rolling temperature of 1,200° C. to 1,275° C. and the longitudinal rolling is performed at a second rolling temperature of 1,100° C. to 1,200° C.;
• and
• step S3.2, introducing the rough-rolled billet into a finish rolling mill for the finish rolling in three rolling passes with reductions of 12% to 14%, 10% to 12%, and 8% to 10% respectively, so as to obtain the finish-rolled billet, wherein the finish rolling is performed at a third rolling temperature of 850° C. to 1,050° C.