METHOD FOR THERMAL PROCESSING OF SEAMLESS CORROSION-RESISTANT PIPES OF OIL ASSORTMENT OF MARTENSITE GRADE STEEL Russian patent published in 2023 - IPC C21D9/08 C21D1/18 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to thermal processing of seamless corrosion-resistant pipes of high-chromium martensite grade steel; it can be used in the production of pipes of oil assortment with a fluidity limit of at least 552 MPa. A method for thermal processing of seamless corrosion-resistant pipes of oil assortment of high-chromium martensite grade steel includes heating to a temperature exceeding a critical point A_c3, cooling, and subsequent high release. Cooling of the pipe is carried out in a water spraying device with a formed water ring diameter 20-45% smaller than an inner diameter of the pipe supplied to cooling and an inclination angle of water-supplying nozzles to the axis of the pipe from 10 to 25°. The pipe is supplied to the water sprayer device with its reciprocating movement for cooling of an outer surface along the entire perimeter and length of the pipe to provide a martensite content in a pipe steel structure of at least 95%. Subsequent high release is carried out at temperatures 15-80°C lower than a critical point A_c1 and with exposure for at least 5 min per 1 mm of a cross-section of a thickness of a pipe wall.

EFFECT: pipes are characterized by high values of strength and impact viscosity, as well as high resistance to carbon-dioxide corrosion.

3 cl, 2 dwg, 1 tbl