Sumitomo Metal Industries, Inc.

Shigeo Uenoya

Toshiro Tomida

Naoyuki Sano

(1) A doubly oriented silicon steel sheet having excellent magnetic characteristics in two directions, i.e. in a rolling direction and in a direction perpendicular to the rolling direction, and most suited for use as material for cores of small-sized transformers, and (2) a method for manufacturing the same. The doubly oriented silicon steel sheet as mentioned above in (1) is characterized in that: Si and Mn are contained in amounts which satisfy a predetermined formula of relation; an average crystal grain is as large as 1 to 8 times the thickness of the sheet as measured on a cross section parallel to the surface of the sheet; and at least 60% of all crystal grains have a size of X/3 to 3X, where X is an average grain size. In the doubly oriented silicon steel sheet, preferably, crystal grains having a crystallographic orientation difference within .+-.15 degrees from a cubic orientation of {100}&lt;001&gt; occupy an areal percentage of not less than 70%, or the thickness of a surface oxide layer of the steel sheet is not greater than 0.5 .mu.m. The method for manufacturing a doubly oriented magnetic steel sheet as mentioned above in (2) includes the steps of hot-rolling and cold-rolling steel containing C in an amount of 0.02% to 0.2% and Si and M in amounts satisfying a predetermined formula of relation, wherein annealing is performed at a temperature not lower than 750.degree. C. and through quick application of heat during cold rolling; and the obtained steel sheet is annealed under reduced pressure through use of an annealing separator. In this method for manufacturing a doubly oriented magnetic steel sheet, preferably, a rolling reduction is 40% to 85% in cold rolling performed before and after intermediate annealing.

Doubly oriented magnetic steel sheet and method for manufacturing the

A method of effectively manufacturing silicon steel sheets with highly accumulated {100} orientations having excellent magnetic characteristics by a single tight-coil annealing or multi-layer annealing. The method can be widely used in the manufacture of magnetic steel sheets. The silicon steel sheet with excellent magnetic characteristics can be obtained by subjecting a cold-rolled silicon steel sheet containing, on a weight basis, not more than 1% of C, 0.2 to 6.5% of Si, and 0.05 to 5.0% of Mn to a tight-coil annealing or a multilayer annealing together with a substance which accelerates decarburization or with a combination of a substance which accelerates decarburization and a substance which accelerates demanganization, as separators in annealing.

Method of manufacturing a silicon steel sheet having improved magnetic

A magnetic steel sheet containing, on a weight basis, 0.2 to 6.5% of Si and 0.03 to 2.5% of Mn, having a crystallographic texture wherein the density of aggregation of {100} planes parallel to the surface of the sheet is not less than 10 times that of non-oriented crystal grains, and having a demanganized layer in which the concentration of manganese decreases from the interior of the sheet toward the surface of the sheet, wherein the ratio between the concentration of manganese in the surface portion of the sheet and that in the mid depth portion of the sheet is not more than 0.90 and wherein the maximum ratio of reduction in the concentration of manganese within the demanganized layer is not more than 0.05 wt %/.mu.m. Magnetic characteristics of the magnetic steel sheet improved by adopting the average grain diameter 0.25 to 10 times the thickness of the sheet and by applying to the sheet a tension smaller than the elastic limit of the sheet in a direction parallel to the surface of the sheet. By employing an appropriate ratio of reduction in the Mn concentration, a relatively high magnetic flux density is obtained without a sharp increase in magnetic flux density, and core loss reduces, thereby providing a non-oriented or doubly oriented magnetic steel sheet having excellent magnetic characteristics and blanking performance.

Growing community of inventors

Osaka, Japan

Shigeo Uenoya