HIGH-STRENGTH DYNAMIC IMPACT RESISTANT STEEL AND METHOD FOR PRODUCTION OF THIS STEEL SHEETS Russian patent published in 2012 - IPC C22C38/50 C21D9/42 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: steel billet containing wt %: C 0.45-0.50, Mn 0.60-0.80, Si 0.17-0.40, Cr 1.0-1.3, Ni 1.2-1.5, Mo 0.25-0.35, V 0.08-0.15, S 0.005-0.01, P 0.003-0.01, Cu 0.1-0.2, Zr 0.005-0.01, W 0.01-0.05, Fe being the rest, is heated to be forged up to 1050-1100°C, then it is forged at 1100-800°C without cooling from the end of forging temperature isothermal annealing is done at 630-670°C followed by cooling along with the furnace, bead-blasting surface conditioning of the forgings is done, then it is heated for hot rolling at 1050-1100°C in the furnace filled with neutral gas (nitrogen or argon), hot rolled in the temperature range 1100-800°C with intermediate cobbing of 8-25% and a total cobbing of not less than 80%, cooled up to ambient temperature, quenched at 900-950°C in oil or water and double tempering at 170-200°C followed by cooling in the air.

EFFECT: increased strength and hardness of the steel sheets and lower susceptibility of steel to brittle fracture.

5 cl, 1 ex, 2 tbl