METHOD FOR MAKING AN ELECTRIC SHEET STEEL WITH ORIENTED GRAINS FOR THE MANUFACTURE OF TRANSFORMER MAGNETIC CIRCUITS IN PARTICULAR

摘要

PURPOSE: A method for improving the magnetic characteristic of a steel sheet is provided to re-heat a slab or a strip in a temperature of under 1350°C before hot rolled pressing. CONSTITUTION: The invention concerns a method for making an electric sheet steel with oriented grains characterized in that the slab or strip has the following composition:less than 0.1 % carbon, more than 2.5 % silicon, less than 0.006 % sulfur, more than 0.002 % manganese, more than 0.008 % aluminium, more than 0.004 nitrogen, more than 0.02 % copper, less than 0.02 % tin. The method consists in subjecting the above slab to temperature less than 1350°C and hot rolling such that:the percentage by mass of non-precipitated sulfur in the form of coarse particles of average diameter not less than 300 nanometers (nm) is higher than 0.004 %; the percentage by mass of precipitated nitrogen only on the form of fine particles of average diameter less than 100 nm is less than 40 % of the total percentage by mass of nitrogen.