PRODUCTION OF HIGH STRENGTH AND HIGH TOUGHNESS STEEL

摘要

PURPOSE:To produce steel which is improved of strength and toughness to a max. extent by hot working steel of Ceq at a specific value or under and controlling the rate of cooling after the end of the hot working and tempering conditions thereafter. CONSTITUTION:An ingot of <=0.45% Ceq refined in a melting furnace such as a converter, an electric furnace or the like and produced by a continuous casting method or an ingot making and blooming method is hot-worked to steel plates, steel pipes or shape steel. The steel material after the end of the hot working is cooled at 5-40 deg.C/sec cooling rate. The material is reheated to 150-500 deg.C and is immediately cooled or is subjected to a tempering treatment wherein the material is kept for <=30min at said temp.