METHOD OF PRODUCING HOT-ROLLED SHEETS FROM CONSTRUCTIONAL LOW-ALLOY STEEL WITH GUARANTEED MAINTENANCE OF CONSTRUCTION PERFOMANCE PROPERTIES AT LOW TEMPERATURES (VERSIONS) Russian patent published in 2017 - IPC B21B1/26 C21D8/02 C22C38/58 

FIELD: metallurgy.

SUBSTANCE: while producing thick sheets, austenitization of continuously cast ingot is carried out at 1200-1220 °C, finish rolling starts at 780-820 °C and finishes at 740-760 °C with a total reduction of at least 80% to a final sheet thickness of not more than 15 mm. Steel contains the following chemical composition, wt %: 0.17-0.20 C, 0.15-0.25 Si, 1.25-1.40 Mn, S≤0.006, P≤0.018, Cu≤0.10, Nb≤0.01, V≤0.01, 0.02-0.05 Al, Ti≤0.03, Fe inevitable impurities - the rest. While producing sheets of 15-25 mm thickness from the steel of the same composition, austenitization of continuously cast ingot is carried out at 1200-1220 °C, finish rolling starts at 830-860°C and finishes at 760-790 °C with a total reduction of at least 75%, wherein after the finish rolling the sheets are rapidly cooled to 620-670 °C. Production versions of the sheets of 40-80 mm, 80-120 mm, 120-160 mm thickness with the same steel composition are also presented. In all versions of the method, the rolling at the draft stage is carried out with one-time reductions of at least 7%.

EFFECT: maintenance of perfomance properties at low temperatures.

12 cl, 3 tbl