METHOD FOR PRODUCING HOT-ROLLED SHEET STRUCTURAL STEEL Russian patent published in 2022 - IPC C21D8/02 C22C38/42 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely, to rolling production, and can be used in manufacturing hot-rolled sheet structural steel with a thickness of 3 to 15 mm used in car building on continuous broad-strip mills. Slabs of the following chemical composition, wt.% are heated: carbon 0.23 to 0.27, silicon 0.17 to 0.37, manganese 0.50 to 0.80, chromium 0.8 to 1.1, sulphur no more than 0.020, phosphorus no more than 0.020, nickel no more than 0.25, copper no more than 0.25, aluminium 0.02 to 0.05, nitrogen no more than 0.012, iron the rest. Rough hot rolling is performed with a semi-finished rolling stock thickness of at least 35 mm, followed by finishing rolling. The temperature of the beginning of rough rolling is 1,050 to 1,150 °C, the temperature of the end of rough rolling is 950 to 1,110 °C, the temperature of the beginning of finishing rolling is 900 to 1,060 °C, and the temperature of the end of finishing rolling is 850 to 900 °C. The resulting sheets of structural steel are cooled with water to the reeling temperature and reeled into rolls at a temperature of 600 to 640 °C. The rolls undergo subsequent annealing at a temperature of 600 to 640 °C with the annealing lasting from 12 to 29 hours.

EFFECT: improvement in the consumer properties of steel, namely, ensured tensile strength of at least 500 MPa, yield strength of at least 400 MPa, elongation of at least 24%, and Brinell hardness of up to 241 MPa, at a lower production cost.

2 cl, 2 tbl