METHOD OF PRODUCING HOT-ROLLED SHEET FROM LOW-ALLOY STEEL Russian patent published in 2016 - IPC C21D8/02 C22C38/44 

FIELD: metallurgy.

SUBSTANCE: invention relates to low alloyed steel of higher heat resistance, used in production of gilled pipes intended for steam boilers, pipes of steam super heaters, pipelines and collector units of high pressure, cylinder parts of gas turbines, various parts operating at temperature of up to +480-500 °C, weld neck flanges, nozzles, rings, branch pipes, T-bends for power equipment and pipelines of thermal power plants. Slab is produced from steel having chemical composition, in wt%: carbon 0.15-0.22, silicon 0.15-0.50, manganese 0.60-1.00, aluminium 0.01-0.06 %, chromium not more than 0.3, nickel not more than 0.3, copper not more than 0.3, molybdenum 0.20-0.50, sulphur not more than 0.007, phosphorus not more than 0.020, nitrogen not more than 0.012, iron and unavoidable impurities - balance. Slabs are heated for rolling to temperature of 1,200-1,250 °C. Multipass reversing rough and finish rolling are carried out. Rough rolling is completed at temperature not higher than 1,100 °C, and finish rolling is performed for 7-11 passes and completed in temperature range of 880-910 °C with relative reduction in final pass from 10 % to 15 %. After rolling and cooling sheets are heat treated at temperature of 900-930 °C with subsequent cooling in air.

EFFECT: providing high level of heat resistance and impact strength.

1 cl, 3 tbl