COLD ROLLED SHEETS FOR DEEP DRAWING MAKING METHOD Russian patent published in 2006 - IPC C21D8/04 C21D9/48 

FIELD: metallurgy, namely processes for cold rolling steel sheets with high drawing properties, possibly used for cold forming of body parts of passenger cars.

SUBSTANCE: method is realized at keeping temperature values of rolling termination and coiling in ranges 850 - 910°C and 540 - 730°C respectively. Cold rolling is performed at total reduction 65 - 88%. Annealing stage is performed at heating up to temperature 700 -750°C and soaking at such temperature for 10 - 25 h. Steel for making cold rolled sheets contains next ingredients, mass %: carbon, 0.001 - 0.006; silicon, 0.005 - 0.04; manganese, O.05 - 0.25; aluminum, 0.01 - 0.08; titanium, 0.01 - 0.09; niobium, no more than 0.05; boron, no more than 0.001; chrome, no more than 0.06; nickel, no more than 0.06; copper, no more than 0.06; sulfur, no more than 0.012; phosphorus, no more than 0.10; nitrogen, no more than 0.006; iron, the balance. If niobium is absent and relation Ti/(4C + 3.43N + 1.5S)≥ 1 is satisfied, reduction degree at skin pass rolling is set in range 0.20 - 0.60% and if given relation is less than 1 it is set in range 0.61 - 1.2%. If niobium is present and next relations of chemical elements content in steel Ti/3.43N ≥ 1 and Nb/7.75C ≥ 1 are satisfied, reduction degree at skin pass rolling is set in range 0.20 - 0.60% and if given relations are less than 1 it is set in range 0.61 - 1.2%.

EFFECT: less loss of yield, improved drawing capability of steel sheets.

7 cl, 3 tbl, 1 ex