METHOD FOR PRODUCTION OF COLD-ROLLED HIGH-STRENGTH ROLLED PRODUCTS OF DIFFERENT STRENGTH CLASSES FROM TWO-PHASE FERRITIC-MARTENSITE STEEL Russian patent published in 2020 - IPC C21D8/02 C21D1/26 C21D9/46 C22C38/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to production of cold-rolled high-strength rolled products of different strength classes from two-phase ferritic-martensite steel, which can be used in automotive industry. Proposed method comprises billet heating, hot rolling, cold rolling and processing in continuous annealing aggregate. Note here that billet is made from steel containing the following components, wt%: carbon 0.11–0.13, silicon 0.02–0.40, manganese 2.0–2.2, chromium 0.25–0.40, molybdenum 0.10–0.30, niobium 0.015–0.025, iron and unavoidable impurities – the balance, in the continuous annealing unit, the rolled metal is heated to annealing temperature, holding, slow cooling, accelerated cooling to the beginning of overageing and overageing, at that, to produce rolled material of strength class 780, heating is carried out to 700–720 °C, strength class 980 heating is carried out to 770–790 °C and strength class 1180 heating is carried out to 730–750 °C, and the rolling speed in the continuous annealing aggregate for strength classes 780 and 1180 is assigned depending on the thickness of the strips in accordance with the relationship V=(80-20h)±10, where V is rolling speed, m/min, h is rolling thickness, mm, 80 and 20 are empirical coefficients, m/min, for rolled material of strength class 980 – in accordance with relationship V=(140-40h)±200, where V is strip speed, m/min, h is rolled stock thickness, mm, 140 and 40 are empirical coefficients, m/min.

EFFECT: increased ductility, expansion of technological capabilities for steel of identical chemical composition of rolled products of various strength classes 780, 980 and 1180.

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