MAKING PROCESS FOR ELECTRIC STEEL PLATES

摘要

hot rolling an electrical steel slab containing by wt. 2.8-3.5 % of Si, 0.060-0.095 of Mn, 0.015-0.035 % of S, 0.015-0.036 % of sol. Al and 0.004-0.012 % of N; precipitation-annealing the rolled sheet; cold-rolling the sheet to the final thickness; decarburiation-annealing the sheet; coating the sheet with an annealing agent containing 3-5 % of TiO and 0.1-1.0 wt.% of Na2B4O7 to 100 of MgO; high temperature annealing the sheet by heating it in H2 and N2 in the range of 600-1200 deg.C at the rate of 15-25 deg.C/hr increase and in H2 at 1200 deg.C for 20 hours to cool. Prior to the high temp. annealing, however, test piece cut from the sheet coated with the annealing agent is heated in 25 % N2 and 75 % H2 in the range of 600-1100 deg.C at the increasing rate of 20 deg.C/hr for secondary recrystallisation annealing to find the presence or not of fine grains among crystal grains in the piece.