Patent ID: 6884306

Claim:
A method of heat treating a steel to produce a mainly bainitic structure, wherein the steel has the following composition in weight percent; carbon 0.6-1.1; silicon 1.5 to 2.0; manganese 1.8 to 4.0; chromium 1.2 to 1.4; nickel 0-3; molybdenum 0.2 to 0.5; vanadium 0.1 to 0.2, balance iron save for incidental impurities; and, wherein the method comprises the steps of: homogenising the steel at a temperature of at least 1150° C. for at least 24 hours; air cooling the steel; subjecting the steel to a temperature between 900° C. and 1000° C.; isothermally transforming the steel at a temperature between 190° C. and 260° C. for 1 to 3 weeks.