Effect of Magnetic Properties by Stress Relief Annealing in Non-Grain Oriented Electrical Steel

Abstract

Recrystallized non-grain oriented electrical steel sheet containing 3.17% Si, 0.35㎜ thick was conducted stress relief annealing(SRA) under various conditions of annealing duration time at 750 °C to investigate recovery of magnetic properties. Magnetic properties of samples with increasing magnetic strength H and frequency were analyzed and compared the difference grain size and texture using EBSD. Magnetic flux density B and core loss W was increased and reduced respectively in particular core loss on traverse direction was significantly improved. Directional anisotropy deviation was decreased. Anomalous loss Pa was reduced as increasing annealing duration time by relieving micro stress on recrystallized sheet after further annealing. Microstructure was slightly changed as developed (001) texture after annealing however magnetic flux density B50 was not more than a predetermined value regardless of the duration time. The purpose of this study is to evaluate the relevance of the magnetic properties with change of texture and grain size after SRA.