Statistical analysis of misorientation to goss orientation of highly grain-oriented silicon steel

Abstract

Grain-oriented (GO) steel is primarily used as a core material for transformers. For better magnetic performance, the high selectivity to the exact {110} 〈001〉 orientation has been a target for GO steel. Commercially available high-grade of GO steel consists of grains with a misorientation <3° from the {110} 〈001〉 orientation. However, the magnetic properties of the commercial GO steel implies that the GO steel should contain grains with larger deviation angles. As GO steel has much larger grains (diameters of several centimeters) than low-carbon steel, the conventional microscopy method used to measure the orientations of the grains is not suitable for GO steel. In this study, Laue diffraction was used to analyze the orientation of large grains of HI-B GO (HGO) steel to obtain statistically reliable topological data and characterize the grain boundaries between abnormally grown grains. The measured area was 6300 cm2, which contained 1230 grains. The analyzed HGO steel sheet had 1/3 of the grains with orientations close to an exact Goss orientation, which was defined as a range of orientations with a misorientation angle <5°, and 2/3 of the grains with higher misorientation to the Goss orientations. The topological and grain-boundary characteristics of the grains based on the misorientation to the exact Goss orientation are discussed in detail.