HOT-ROLLED PRODUCTS FROM THE STRUCTURAL STEEL MANUFACTURING METHOD Russian patent published in 2019 - IPC C21D8/02 C22C38/00 B21B1/26 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy. Smelting the steel, containing, wt.%: carbon 0.09–0.12, manganese 1.20–1.45, silicon 0.50–0.80, nickel, copper not more than 0.1 each, chromium 0.15–0.30, molybdenum not more than 0.01, vanadium, niobium not more than 0.01 each, titanium 0.010–0.030, iron and inevitable impurities are the rest, at that, the rolling temperature parameters are selected as follows: the finish rolling temperature is higher than the Ar₃ point by the value, calculated by the formula: ΔTkp=(-68.44+3h_roll+191.47*Se)*K, coiling temperature below Ar₁ by the value calculated by the formula: ΔTsm=(423.77+6.33h_roll-845.15*Se)*K, where K=0.99÷1.01 is the empirical coefficient, Ar₁ and Ar₃ according to the formulas: Ar₁=729.2-9.24[C]+12.13[Si]-15.56[Mn]+17.71[Cr]-46.44[Ni], Ar₃=879.2-94.24[C]-21.13[Si]-25.56[Mn]+47.71[Cr]+16.44[Ni], and the carbon equivalent is by the formula: Se=C+Mn/6+Si/24+Cr/5+Mo/4+Ni/40+Cu/13+V/14+P/2.

EFFECT: production of the 345 strength category sheet steel with the yield strength to temporary resistance ratio of not more than 0,75.

1 cl, 3 tbl