PROCEDURE FOR PRODUCTION OF ANISOTROPIC ELECTRO-TECHNICAL STEEL WITH LOW SPECIFIC LOSSES FOR RE-MAGNETISATION Russian patent published in 2010 - IPC C21D8/12 

FIELD: metallurgy.

SUBSTANCE: there is melted steel with contents, wt %: from 2.5 to 3.6 of silicon, from 0.05 to 0.40 of manganese, from 0.02 to 0.065 of carbon, from 0.004 to 0.013 of nitrogen, less, than 0.012 of sulphur, less, than 0.005 of titanium, and from 0.020 to 0.035 of acid-soluble aluminium. Further, there is performed continuous steel casting into slabs of 220-270 mm thickness. At temperature of surface not less, than 450°C slabs are placed into a continuous furnace and are heated to 1100-1200°C. Further, the slabs are hot rolled, annealed, and cold rolled in one or several stages with ageing between runs. Cold rolled strip is continuously annealed at heating rate from 20 to 50°C/s to temperature 750-800°C, de-carbonised at temperature 790-840°C and conditioned in atmosphere with ratio Temperature is raised at 5-50°C maximum to 870°C and product is conditioned during 10-30 sec in atmosphere with ratio Nitriding is performed at temperature from 780 to 850°C in nitrogen-hydrogen atmosphere with ratio containing ammonia NH₃. Further, temperature is raised at 30-200°C, maximum to 1050°C. The product is conditioned during 15-30 s in atmosphere with ratio then cooled to temperature 600-100°C in dry nitrogen-hydrogen atmosphere, where contents of hydrogen are not less, than 10 %.

EFFECT: low losses for re-magnetisation and high magnetic induction.

4 cl, 2 tbl