METHOD OF PRODUCTION OF THE PLATE IRON Russian patent published in 2008 - IPC C21D8/02 C22C38/58 

FIELD: metallurgy industry; other industries; production of the plate iron rolling.

SUBSTANCE: the invention is pertaining to the method of the rolled iron may be used at the rolling process on the reversible rolling mills of the sheets for the stamping and welding of the coupling details for the long-distance and field pipelines with their subsequent thermal improvement. For improvement of the mechanical properties and the raise of the commercial output the slab is heated up to the temperature of 1170-1190°С, conduct the multiple run roughing and the finishing multiple run rolling start at the temperature of not above 970°С with the total compaction of 50-70 % and complete the operations at the temperature of not above 900°С.The hot-rolled plates are normalized at the temperature of 910-940°С with cooling in the open air, and before the hot rolling the continuously casting slabs are exposed to the annealing at the temperature of not above 750°С. Besides, the low-alloyed steel has the following chemical composition (in mass%): C - 0.03-0.07; Si - 0.20-0.40; Mn - 1.4-1.8; Al - 0.02-0.05; Nb - 0.03-0.06; Ti - 0.01-0.04; V - 0.06-0.09; Cr - 0.1-0.3; Ni - 0.2-0.5; Cu - 0.1-0.3; Mo - 0.08-0.17; S ≤ 0.005; P ≤ 0.015; N ≤ 0.011; Fe - the rest.

EFFECT: the invention ensures the improved mechanical properties of the plate iron and the increased output of the commercial products.

4 cl, 3 tbl, 1 ex