MANUFACTURING METHOD OF THICK LOW-ALLOY ROLLED PLATES Russian patent published in 2012 - IPC C21D8/02 C22C38/38 

FIELD: metallurgy.

SUBSTANCE: continuously cast blank is obtained from steel with the following component ratio, wt %: 0.04-0.10 C, 0.15-0.40 Si, 1.4-1.75 Mn, 0.31-0.60 Ni, 0.05-0.22 Mo, 0.065-0.10 Nb, 0.025-0.06 V, Cr≤0.25, Cu≤0.3, Al≤0.08, Ti≤0.05, iron and impurities with content of each component of the impurity of less than 0.03% is the rest; at that, Nb+Ti+V≤0.18, Cr+Ni+Cu≤1.0, and carbon equivalent is C_equiv=0.43. Continuously cast blank is heated above 1150°C at least during 7.5 hours. Roughing-down is carried out with value of relative reduction in pass of not less than 8%, excluding the last pass, for thickness of intermediate blank, which is equal to 115-165 mm at thickness of finished rolled stock of less than 33 mm inclusively, and for thickness of intermediate blank, which is equal to 166-195 mm at thickness of finished rolled stock of more than 33 mm; cooling of intermediate blank after roughing-down is performed to 730-765°C. Finish rolling is carried out first in transverse direction, and then in longitudinal direction with rolling end temperature of 720-760°C. End temperature of accelerated cooling of finished rolled stock is not less than 540°C.

EFFECT: increasing strength properties of strip material at maintaining sufficient ductility and cold resistance.

1 ex