MANUFACTURING METHOD OF COLD-ROLLED ELECTRICAL ISOTROPIC STEEL WITH IMPROVED FLATNESS Russian patent published in 2013 - IPC C21D8/12 C22C38/02 

FIELD: metallurgy.

SUBSTANCE: method involves making of steel containing the following components, wt %: not more than 0.010 of carbon, 1.2-3.5 of silicon, not more than 1.6 of aluminium, not more than 0.50 of manganese, not more than 0.14 of phosphorus, not more than 0.01 sulphur, iron and inevitable impurities are the rest, pouring, hot rolling, normalising annealing of hot-rolled straps if required, etching of hot-rolled straps, cold rolling, recrystallisation annealing of cold-rolled straps at exposure temperature of 930-1080°C. Cooling of straps after recrystallisation annealing is performed at two stages; at the first stage, retarded cooling is performed at the speed of 0.2-4°C/sec from exposure temperature to temperature Ar₂≤T_n≤820°C, and at the second stage, accelerated cooling is performed at the speed of 5-17°C/sec, where: Ar₂ ⁼768 - Curie point, magnetic steel transformation temperature, °C; T_n - strap cooling temperature at the first stage, °C.

EFFECT: improving qualitative characteristics of cold-rolled steel at reduction of non-flatness and increase in coefficient of filling of finished straps.

1 tbl, 1 ex