Bainite steel with excellent low-temperature toughness and its manufacturing method

摘要

The present invention relates to a steel sheet having a chemical composition of C: 0.01 to 0.04%, Mn: 1.2 to 2.0%, Si: 0.1 to 0.3%, Al: 0.02 to 0.06%, Ti: 0.01 to 0.03% P: 0.02% or less, N: 10 to 100 ppm, O: 0.01 to 0.05%, O: 0.04 to 0.06%, V: 0.05 to 0.07%, Mo: 0.15 to 0.25, Ca: 10 to 100 ppm, Fe, and other unavoidable impurities, and a steel slab made of the above composition is heated at a temperature in the range of 1050C to 1300C and then heated to a temperature of 100C to 200C C at a high temperature; and accelerating and cooling the slab of the steel after completion of the rolling. The present invention also provides a method for producing a bainite steel excellent in low temperature toughness.