METHOD FOR PRODUCING LOW-ALLOY STEEL STRIPS Russian patent published in 2023 - IPC C21D8/02 C22C38/58 C22C38/54 C22C38/50 C22C38/48 C22C38/46 C22C38/44 C22C38/42 

FIELD: metallurgy.

SUBSTANCE: invention relates namely to a method for producing hot-rolled steel used for the manufacture of side members for trucks, as well as for the production of highly loaded structures. A continuously cast billet of low-alloy steel is heated, containing components in the following ratio, wt.%: carbon 0.15-0.25, silicon 0.3-0.7, manganese 1.4-1.8, sulphur not more than 0.010, phosphorus not more than 0.020, chromium not more than 0.30, nickel not more than 0.30, copper not more than 0.30, aluminium 0.01-0.08, niobium not more than 0.010, vanadium not more than 0.10, titanium from 0.10 to less than 0.23, molybdenum not more than 0.010, calcium not more than 0.005, nitrogen not more than 0.010, boron not more than 0.005, iron and inevitable impurities the rest, with the total content of Nb+V+Ti≤0.23%, and carbon equivalent C_e≤0.6%. Rough rolling is carried out to an intermediate thickness of the rolled material, which is 3.5-5.5 strip thicknesses. Finish rolling to produce strips is carried out at a speed of no more than 7.0 m/s, starting at a temperature of 940-1010°C and finishing at a temperature of 850-900°C. Accelerated cooling of the strips is carried out in two stages, with the first stage of cooling carried out at a rate of 10-30°C/s from the finish rolling temperature to a temperature of 550-680°C, after which the second stage of cooling is carried out at a rate of 6-15°C/s up to a winding temperature of 510-600°C. Heat treatment of the strips is carried out by heating to temperature Ac3±80°C with a duration of 1.0-2.0 min/mm of strip thickness, followed by cooling in air.

EFFECT: increased productivity of strip production while maintaining the required level of mechanical properties.

1 cl, 2 tbl