METHOD FOR PRODUCING OF COLD-ROLLED STEEL FOR COLD PRESSING Russian patent published in 2007 - IPC C21D8/04 C22C38/12 

FIELD: metallurgy, in particular, manufacture of steel used in automobile building.

SUBSTANCE: method involves smelting steel containing components used in the following ratio, wt%: carbon 0.002-0.015; silicon 0.005-0.050; manganese 0.05-1.0; phosphor 0.005-0.09; sulfur 0.003-0.020; aluminum 0.02-0.07; nitrogen 0.002- 0.007; titanium 0.0005-0.040, niobium no more than 0.060; iron and unavoidable impurities the balance, on condition that C_ef=[C]-C_Ti-C_Nb≥0.0006%, where C_ef is effective content of titanium or niobium non-bound carbon, [C] is total content of carbon in steel, C_Ti is content of titanium bound carbon, with titanium [Ti] to nitrogen [N] content ratio making [Ti]/[N]<3.43; C_Ti=0, with [Ti]/{N]≥3.43 C_Ti=([Ti]-3.43N)/4; C_Nb is content of niobium bound carbon, C_Nb=Nb/7.74; C_ef+0.05[P]≥0.003%, where [P] is phosphor content in steel; providing steel casting; hot rolling; winding strips into rolls at temperature not in the excess of 650 C; performing cold rolling and recrystallization on annealing in cover furnace with regulated heating: first to temperature of 450-500 C at heating rate of at least 50 C/hour, then to temperature of up to 550-600 C at heating rate not in the excess of 30 C/hour, then at heating rate not in the excess of 50 C/hour to temperature of 700 C, and, when necessary applying coating.

EFFECT: increased tendency to BH-effect, including after thermal processing in cover furnaces, and provision for keeping of high formability.

3 cl, 1 tbl, 7 ex