METHOD FOR PRODUCING PLATES FOR MANUFACTURE OF ELECTRIC-WELDED PIPES FOR MAIN PIPELINES (OPTIONS) Russian patent published in 2023 - IPC C21D8/02 C22C38/58 C22C38/54 C22C38/50 C22C38/48 C22C38/46 C22C38/44 C22C38/42 C22C38/40 

FIELD: metallurgy.

SUBSTANCE: production of rolled sheets on a reversible plate mill for the manufacture of electric-welded pipes for main pipelines with a diameter of up to 1420 mm. A continuously cast steel billet is obtained with the following ratio of elements, wt.%: carbon 0.03-0.07, silicon 0.10-0.35, manganese 1.70-2.10, sulfur no more than 0.004, phosphorus no more than 0.015, chromium no more than 0.30, nickel 0.40-1.00, copper no more than 0.50, aluminum 0.02-0.08, titanium 0.001-0.03, molybdenum 0.10-0.50, vanadium no more than 0.10, niobium 0.02-0.10, nitrogen no more than 0.008, boron 0.0003-0.001, calcium 0.0005-0.006, if necessary REM no more than 0.002, the rest is iron and inevitable impurities. The workpiece is austenitized at a temperature of 1150-1230°C subsequent rolling. Roughing-down starts at a temperature not lower than 980°C and carry out it to a thickness of the rolled product, which is at least 4 thicknesses of the finished rolled product, and finishing rolling starts at a temperature of 730-870°C and finish at a temperature of 670-850°C. Accelerated cooling of the finished product is carried out at a cooling rate of 10-35°C/s, starting at a temperature of 630-830°C and ending at a temperature of 40-150°C, and final cooling in air.

EFFECT: production of rolled strips of strength class K80 is ensured with a CTOD-20 guarantee and operating temperatures up to -60°C.

27 cl, 4 tbl