FIELD: metallurgy.
SUBSTANCE: invention relates to steel sheet manufacturing for high-strength pipes, welded by means of contact electric welding. Hot-rolled steel sheet contains (wt %): C - approximately from 0.02 up to 0.06, Si - approximately from 0.05 up to 0.5, Mn - approximately from 0.5 up to 1.5, P - approximately 0.01 or less, S - approximately 0.0010 or less, Al - approximately from 0.01 up to 0.1, Nb - approximately from 0.01 up to 0.1, Ti - approximately from 0.001 up to 0.025, Ca - approximately from 0.001 up to 0.005, O - approximately 0.003 or less, N - approximately 0.005 or less, and at least one element, selected from the group: V - approximately from 0.01 up to 0.1, Cu - approximately from 0.01 up to 0.5, Ni - approximately from 0.01 up to 0.5 and Mo - approximately from 0.01 up to 0.5, Fe and unavoidable admixtures. Content of elements in groups, including C, Si, Mn, Cu, Ni, Mo, V and Ca, O, S, fulfilling particular requirements, and microstructure of steel sheet preliminary for 95% by volume or more is fromed by bainitic ferrite. Method of sheet manufacturing includes reheating of steel slab up to the temperature from 1000°C up to 1300°C, hot rolling at final rolling temperature equal to (Ar3-50°C) or more, immediate following cooling of hot-rolled sheet, winding of sheet into the reel at temperature preliminary 700°C or less and slow cooling of roll sheet.
EFFECT: steel sheet allows high ultimate tensile strength, high impact elasticity and well durability to hydrogen-stress cracking.
10 cl, 3 tbl, 3 dwg, 1 ex
