METHOD FOR PRODUCTION OF ROLLED STEEL FOR THE MANUFACTURE OF FLEXIBLE PIPES FOR COILED TUBING (VARIANTS) Russian patent published in 2022 - IPC C21D8/02 C22C38/54 C22C38/50 B21C37/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to a method for the production of rolled steel for the manufacture of flexible pipes for coiled tubing. In the steelmaking unit, steel is smelted containing the following components, wt.%: carbon 0.07-0.18, silicon 0.15-0.60, manganese 0.5-1.2, sulfur no more than 0.005, phosphorus no more than 0.015, chromium 0.2-1.0, nickel 0.02-0.4, copper 0.301-0.5, aluminum 0.01-0.15, vanadium not more than 0.15, niobium 0.001-0.15, titanium 0.001-0.15, molybdenum 0.001-0.35, calcium not more than 0.010, nitrogen not more than 0.01, one or more components from the group: boron not more than 0.003, oxygen not more than 0.004, hydrogen not more than 0.001, tin not more than 0.010, lead not more than 0.010, bismuth is not more than 0.010, Fe is the rest. Its out-of-furnace processing and casting is performed. After casting, the steel is heated for rolling to a temperature of 1180-1250 °C and hot rolling is carried out, while the temperature of the beginning of the finishing hot rolling is 1000-1120 °C, and the temperature of the end of rolling is 800-950 °C. The strips are wound into a roll at a temperature of 480-600°C.

EFFECT: present invention enables to produce flexible pipes from the resulting rolled steel that have high mechanical properties, corrosion resistance and increased resistance to low-cycle fatigue.

3 cl, 4 tbl