UA101439C2 - method for production of a hot rolled plate from steel of X80 strength grade for production of line pipes - Google Patents

Abstract

The invention relates to the field of metallurgy, in particular to a method for production of a hot rolled plate from steel of X80 strength grade for production of line pipes. The method involves heating the plate slab to the austenitisation temperature, multipass rough and finish rolling with the controlled temperature of the rolling end and subsequent cooling of the rolled metal with water, and finish rolling is carried out with to relative compression of at least 70%, the finish rolling end temperature is maintained at 660-, and cooling of the rolled metal is carried out at a rate of 2-4 °C/s to a temperature of 500-, after which the resulting rolled metal is cooled in the stack in the temperature range of 400- and then each sheet is cooled on the roller bed of the cooler, at that the steel has the following chemical composition , wt. %: carbon - 0.03-0.05, silicon - 0.12-0.25, manganese - 1.70-1.85, aluminum - 0.02-0.04, niobium - 0,04-0, 08, vanadium - 0.03-0.06, molybdenum - 0.15-0.30, nickel - 0.10-0.35, copper - 0.15-0.30, chromium - not more than 0.10, titanium - 0,010-0,020, nitrogen - no more than 0,008, phosphorus - not more than 0,015, sulfur - not more than 0,002, iron is the rest, the carbon equivalent is not more than 0.43%. The invention provides production of a complex of mechanical properties of the hot rolled plate that meets the requirements of the rolled metal for pipes of X80 strength category, due to the use of the steel of claimed chemical composition and modes of controlled rolling and cooling.