METHOD OF PRODUCING HOT-ROLLED WIDE-STRIP STEEL Russian patent published in 2013 - IPC B21B1/26 

FIELD: process engineering.

SUBSTANCE: proposed method comprises hot rolling, accelerated strip cooling at preset temperatures, and coiling. Rolled stock strength is increased in rolling steel sheet of ferrite-martensitic steel structure containing 0.09…0.11 wt % of carbon, 0.37…0.65 wt % of silicon, 1.25…1.60 wt % of manganese, 0.48…0.57 wt % of chromium, and 0.02…0.1 wt % of nickel at relationship between yield point and ultimate strength of ≤ 0.8 c σ_m=450…1000 N/mm². Note here that between preliminary and final cooling, rolled stock is held in air. Note also that metal temperature in final pass exceeds temperature of Ar₃ by 0…25°C, while temperature after preliminary accelerated cooling is kept lower than that of Ar₁ by Δ_ac=-0.0005 σ_m ² +0.99 σ_m-342.84. Note that coiling temperature is kept lower than Ar₁, by Δ_coil=-0.0013 σ_m ²+2.33 σ_m-496.5. Note that magnitudes of Ar₃ and Ar₁ are calculated by formulae: Ar₃=879.2-94.24 [C]-21.13 [Si]-25.56 [Mn]+47.71 [Cr]+16.44 [Ni]; Ar₁=729.2-9.24 [C]+12.13 [Si]-15.56 [Mn]+17.71 [Cr]-46.44 [Ni], where [C], [Si], [Mn], [Cr], [Ni] stand for said content of said elements in steel in wt %.

EFFECT: higher quality of rolled stock.

1 ex