MANUFACTURING METHOD OF ROLLED STOCK FROM HIGH-STRENGTH COLD-RESISTANT STEEL Russian patent published in 2015 - IPC C21D8/02 C22C38/38 C22C38/40 B21B1/26 

FIELD: metallurgy.

SUBSTANCE: steel containing the following components, wt %, is made: C 0.03-0.010, Mn 1.2-1.8, Si 0.1-0.5, Nb 0.01-0.10, V 0.05-0.10, Ti 0.005-0.04, Mo not more than 0.04, Cr not more than 30, Ni not more than 0.30, Cu not more than 0.30%>, Al 0.01-0.05, N 0.007-0.012, S not more than 0.005, P not more than 0.015, and Fe is the rest. The total content is V+Nb+Ti≤0.15, C_"e"≤0.41, and continuous pouring of steel into a slab is performed. The obtained slab is heated up to 1190-1280°C and roughing is performed in the area of austenite recrystallisation with relative swaging of 45-85%; then, the roll is cooled down at the cooling rate of 0.7÷1.8°C/sec to the finish rolling beginning temperature of 980÷900°C; finish rolling is performed in the area of absence of recrystallisation with the total deformation of 60-80% and with the completion of deformation in the lower part of area γ at the finish rolling end temperature T_roll.end=A_r3+(30÷80)°C; accelerated cooling is performed at two stages; with that, at the first stage, the strip is cooled down at the rate of 4-12°C/sec to the temperature of 530-670°C, and cooling of the strip at the second stage is performed at the rate of 4.0-0.5°C/sec to the strip coiling temperature.

EFFECT: providing cold resistance of a rolled stock, improving weldability and obtaining the rolled stock with the thickness of 8-20 mm with a ferrite-bainite microstructure.

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