SILICON STEEL PLATE REMARKABLY LOW IN HIGH FREQUENCY IRON LOSS

摘要

PROBLEM TO BE SOLVED: To remarkably lower high frequency iron loss by forming a Si concentration gradient in the thickness direction of a steel plate so as to increase the Si concentration at the surface and controlling the concentration at the steel sheet center part and at the steel plate surface part to equal to or above a specific value. ;SOLUTION: The Si concentration at the center part of the silicon steel sheet in the thickness direction is controlled to ≥3.4 wt.% and the Si concentration at the steel sheet surface part is controlled to 5 wt.%, preferably substantially 6.5 wt.%. The silicon steel plate contains preferably C≤0.02 wt.%, 0.05 wt.%≤Mn≤0.5 wt.%, P≤0.01 wt.%, S ≤0.02 wt.%, 0.001 wt.%≤sol.Al≤0.06 wt.% and N ≤0.01 wt.% and a part, where the Si concentration is 5-8 wt.%, is controlled to occupy ≥10%, preferably 15% to ≥25% of the thickness in the depth direction of the plate from both front surface and back surface. Where, the Si concentration of the surface of the steel sheet is desirably ≤8% in consideration of the lowering of machinability of the steel plate.;COPYRIGHT: (C)1999,JPO