- Method of producing steel using direct quenching and self tempering

摘要

The present invention relates to a method for producing steel using direct quenching-magnetic considerations, in terms of weight% C: 0.30% to 0.50%, Mn: 0.50% to 1.60%, Si: 0.10% to 0.50%, Cr: 0.40% to 2.50 %, Mo: 0.10% to 1.00%, Ni: 0.25% to 2.00%, Al: 0.010% to 0.050%, V: 0.010% to 0.30%, N: 0.002% to 0.020%, S: 0.01% to 0.10%, Step of heating the steel material consisting of trace amounts of Nb, B and unavoidable impurities during steelmaking to a temperature of 900 ° C to 1250 ° C and performing rough rolling and intermediate rolling: Final rolling at a rolling reduction of 15% or more at a temperature of 830 ° C to 880 ° C. Performing a step; And directly quenching at a cooling rate of 200 ° C./sec to 450 ° C./sec immediately after the final rolling. Unlike conventional methods for producing high-strength tough steel by reheat quenching, it is possible to reduce manufacturing cost by omitting the reheating heat treatment process, and also improve productivity by suppressing quench cracks and warpage caused by uneven quenching during reheat quenching. It has a useful effect.