METHOD OF PRODUCING THICK-WALL PIPE STEEL Russian patent published in 2016 - IPC C21D8/02 B21B1/32 C22C38/38 C22C38/58 C22C38/40 

FIELD: metallurgy.

SUBSTANCE: to increase strength properties of sheets with thickness of 14-20 mm of pipe steel with strength class K60 at maintaining sufficient ductility and impact strength are produced continuously-cast slab thickness 300±20 from steel containing, wt%: carbon 0.06-0.08, silicon 0.25-0.40, manganese 1.60-1.70, sulphur not more than 0.003, phosphorus not more than 0.013, chromium not more than 0.08, nickel 0.20-0.30, copper 0.10-0.20, aluminium 0.025-0.045, nitrogen not more than 0.008, vanadium 0.020-0.035, titanium 0.015-0.030, niobium 0.040-0.055, iron and impurities is balance, wherein carbon equivalent is C_EQ ≤ 0.43, then slab is heated to temperature of 1,200-1,220 °C, rough rolling at 1,040±60 °C for 7-10 passes at reduction of not less than 12 % per pass by thickness of 95±15 mm, cooling of intermediate roll - 860±20 °C, finish rolling with total reduction of 75-85 %, rolling end temperature set 855±15 °C and accelerated cooling at a rate of 14-22 °C/s to temperature of 555±15 °C.

EFFECT: invention can be used for production of low alloyed pipe steels.

1 cl, 3 tbl, 1 ex