PRODUCTION METHOD OF COLD-RESISTANT STEEL SHEETS Russian patent published in 2008 - IPC C21D8/02 C22C38/24 

FIELD: metallurgy.

SUBSTANCE: invention concerns metallurgy field. For increasing cold-resistance and mechanical properties of welded structures, operating at temperatures from plus 120°C till minus 60°C in cross-sections till 160 mm, blank is heated higher then temperature Ac₃, it is implemented its preliminary deformation at temperature 1000-850°C with summary draughting 65-75%, final deformation at temperature 750-700°C till requested sheet thickness with particular draughtings not less then 12% per pass at summary draughting not less then 60% and sheet is cooled at first with velocity more then 35°C/min till temperature 150±10°C, and then on open air and it is exposed to abatement at temperature 650±20°C with holding 1.0-1.5 min per mm of thickness with further cooling on open air. Blank is received from steel, containing wt %: carbon 0.07-0.09, manganese 1.30-1.60, silicon 0.50-0.70, chrome 0.05-0.20, nickel 0.05-0.10, vanadium 0.02-0.04, aluminium 0.020-0.040, niobium 0.02-0.04, copper 0.05-0.15, calcium 0.002-0.004, sulphur 0.002-0.005, phosphorus 0.005-0.010, nitrogen 0.006-0.008, and iron - the rest, at fulfillment of conditions: (chrome + nickel + copper) ≤ 0.40; (sulphur + phosphorus) ≤ 0.013; (manganese + niobium + vanadium)/(carbon + nitrogen) ≤21, and fracture toughness index during welding (P_fr) ≤ 0.21.

EFFECT: increasing of cold-resistance and mechanical properties of welded structures.

6 cl, 2 tbl, 1 ex