PROCEDURE FOR PRODUCTION OF HEAVY PLATE LOW ALLOYED ROLLED STEEL Russian patent published in 2011 - IPC C21D8/02 

FIELD: metallurgy.

SUBSTANCE: there is melted steel containing following ratio of components, wt %: C-(0.03-0.08), Si-(0.10-0.35), Mn-(1.4-1.9), Ni-(0.1-0.28), Mo-(0.05-0.14), Cr≤0.12, Cu≤0.12, B≤0.0005, Al≤0.05, Nb+Ti+V≤0.17, iron the rest and additives with contents of each additive element less, than 0.03 %. Carbon equivalent is C_eqv<0.40. Steel is continuously cast. A work piece is heated at 1170-1210°C during not less, than 7 hours. Further, it is roughed at change from drawing to marking out width at temperature not below 950°C with thickness corresponding to 4.0-5.5 of thickness of finished strip and with relative reduction per pass not less 10 %. Semi-finished work piece is cooled in air to 770-800°C. Also, width marking out is completed at the stage of finish rolling in not more, than two passes with summary reduction 8-15%, whereupon the work piece is lengthwise rolled and reduced for not less, than 8 % per pass except for two last passes, where degree of reduction is not less, than 1 %. Finish rolling is completed at temperature not below 740°C. Further, strip is cooled to temperature specified depending on carbon equivalent C_eqv from ratio: T_coef=(500-C_eqv+385°C)±15°C.

EFFECT: increased strength properties of strip at maintaining ductility and cold resistance.

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