COLD-RESISTANT ROLLED PLATE MANUFACTURING METHOD (VERSIONS) Russian patent published in 2009 - IPC C21D8/02 C22C38/12 C21D9/46 

FIELD: metallurgy industry.

SUBSTANCE: invention refers to metallurgy. Plate stock is made from steel containing as follows, wt %: C (0.04-0.10), Mn (1.00-1.40), Si (0.15-0.35), Ni (0.10-0.80), Al (0.02-0.06), Mo (0.01-0.08), Nb (0.02-0.06), V (0.02-0.10), S (0.001-0.008), P (0.003-0.012), and iron - the rest, then it is heated up to 1140-1170°C, pre-deformed with total reduction ratio of 58-65% with specified minimum reductions at first four passes: (12-15%)-(13-17%)-(14-18%)-(14-20%) - at temperature of 940-990°C; after that it is cooled by the value of 70-100°C, finally deformed at 830-750°C with total reduction ratio of 35-42%, cooled very quickly up to 550-400°C, and then cooled slowly in a caisson up to temperature of not more than 150°C. According to the second version, the plate stock is made from steel containing as follows, wt %: C (0.04-0.09), Mn (1.00-1.60), Si (0.15-0.30), Ni (0.10-0.80), Al (0.02-0.06), Mo (0.01-0.08), Nb (0.02-0.08), V (0.02-0.08), S (0.001-0.008), P (0.003-0.012), and iron - the rest, then it is heated up to 1250-1270°C, fractional deformation is carried out at 850-970°C, after that rolled plate is cooled at the rate of not more than 0.5-1.0°C/s up to 800-650°C, then at the rate of not more than 0.1°C/s up to temperature of not more than 200°C and then in the air; after that it is heated up to 940-960°C, kept for 1.5-2.0 min/mm, cooled at the rate of 7-40°C/s up to temperature of not more than 100°C and heated once more up to 650-680°C, kept for 2.0-3.0 min/mm, and cooled in the air.

EFFECT: improving cold-resistant properties of rolled plate up to 70 mm thick, and improving plate weldability and strength.

2 cl, 2 ex, 3 tbl