METHOD FOR HEAT TREATMENT OF ISOTROPIC ELECTRICAL STEEL COLD-ROLLED STRIP Russian patent published in 2006 - IPC C21D8/12 

FIELD: ferrous metallurgy, in particular decarbonization/recrystallization annealing of isotropic electrical steel cold-rolled strip in apparatus of continuous treatment in protective controlled atmospheres.

SUBSTANCE: claimed method includes decarbonization/recrystallization annealing of isotropic electrical steel cold-rolled strip containing (mass %) carbon 0.0055-0.06; silicon not more than 3.2; aluminum not more than 1.0; manganese not more than 1.5; phosphorus not more than 0.40; and balance: iron and inevitable impurities, in nitrogen/hydrogen protective controlled atmosphere at 780-1100°C wherein hydrogen content in nitrogen/hydrogen atmosphere is adjusted according to carbon content in steel before annealing and cold-rolled strip thickness in conformity with equation of wherein moisture of nitrogen/hydrogen atmosphere (based on dew point) is from +1°C to +40°C; H₂ is hydrogen content in nitrogen/hydrogen atmosphere, %: K₁ and K₂ are experimentally determined values: K₁ = 17.5 %; K₂ = 25 % at h < 0.70 mm; K₂ = 46 % at h >= 0.70 mm; h is cold-rolled strip thickness; C is carbon content in steel before annealing, %.

EFFECT: decreased specific magnetic loss due to very low carbon concentration in finished isotropic electrical steel.

2 cl, 1 ex, 1 tbl