METHOD FOR PRODUCTION OF HOT-ROLLED SHEETS FROM LOW-ALLOY STEEL Russian patent published in 2016 - IPC C21D8/02 C22C38/38 

FIELD: metallurgy.

SUBSTANCE: to obtain rolled metal with thickness to 21.0 mm of strength class with guaranteed ultimate strength of 510-550 MPa for duty objects with high corrosion resistance in hydrogen and hydrosulphuric environments, resistance to brittle fracture at negative temperature is continuously cast billet with thickness of no more than 250 mm from steel containing, wt%: 0.04-0.070 C, 0.20-0.30 Si, 0.90-1.10 Mn, 0.20-0.30 Cr, N i≤ 0.25, Cu ≤ 0.25 %, Mo ≤ 0.35, 0.004-0.009 Ti, V ≤ 0.06, 0.02-0.035 Nb, N ≤ 0.007, 0.02-0.04 Al, S ≤ 0.001, P ≤ 0.010, Fe and admixtures as rest, at that total content of Cr + Ni + Cu of not more than 0.70 % , carbon equivalent C_e ≤ 0.40 %, parameter of resistance to cracking in welding P_cm≤0.21 %, austenization of continuously cast billet is performed to temperature of 1190-1230°C. Roughing of workpiece is started at temperature of not lower than 960 °C and is to thickness making not less than 5.5 of thickness of finished sheet with relative reduction per pass of not less than 10 %. Finish rolling is started for final thickness sheet to 16 mm at temperature of 900-930 °C, and for sheet final thickness of more than 16 mm at a temperature of 870-900 °C and is terminated to final thickness sheet to 16 mm at 880±10 °C, and for sheet final thickness of more than 16 mm at temperature of 850±10 °C, then sheets are subjected to accelerated cooling to temperature 430-470 °C at rate of not less than 20°C/s.

EFFECT: method for production of rolled stock for duty objects with high corrosion resistance in hydrogen and hydrosulphuric environments.

2 cl, 3 tbl