High strength, high toughness, heat-cracking resistant bainite steel wheel for rail transportation and manufacturing method thereof

A bainite steel wheel for rail transportation, comprising:

• carbon C:
• 0.15-0.25%;
• silicon Si:
• 1.40-1.80;
• manganese Mn:
• 1.40-2.00%;
• copper Cu:
• 0.20-0.80%;
• boron B:
• 0.0003-0.005%;
• nickel Ni:
• 0.10-0.60%;
• phosphorus P≤0.020%;
• and
• sulphur S≤0.020%;
• wherein the remaining is iron and unavoidable residual elements;
• wherein 1.50%≤Si+Ni≤3.00%, and 1.50%≤Mn+Ni+Cu≤3.00%;
• wherein the portion of the bainite steel wheel that is between the surface of a rim tread and 40 millimeters below the rim tread is organized into a microstructure of a carbide-free bainite structure, wherein the carbide-free bainite structure comprises a supersaturated lath ferrite in nanometer scale, wherein a film-shaped carbon-rich residual austenite in nanometer scale is interspersed among the supersaturated lath ferrite, and wherein a volume percentage of the residual austenite is 4%-15%;
• and
• wherein the microstructure of the bainite steel wheel was formed by the steps of smelting, refining, molding, and heat treatment processes, wherein the heat treatment process comprises heating a molded wheel to austenite temperature by heating to 860-930° C. and maintaining at the temperature for 2.0-2.5 hours, intensively cooling a rim tread with a water spray to a temperature below 400° C., and performing tempering treatment.