Repeatability and stability study of residual magnetic field for domain wall characterization

Abstract

Residual magnetic field (RMF) for metal material has a relationship with material stress status. Bridging the relationship between macro parameters and material microstructure is an essential step to deal with the characterization of residual stress. This paper applies magneto-optical Kerr microscopy (MOKE) with the help of magneto-optical indicator film (MOIF) to observe and analyze variations of magnetic domain pattern under different stress conditions of high permeability grain oriented electrical steel (HGO steel). Experiment about repeatability is carried under cyclic stress applications and the stability study is proceeded during the relaxation time after release of stress. By using two domain texture features, mean value (MV) of domain wall image intensity linked to domain rotation to characterize RMF amplitude and the angular second moment (ASM) related with domain wall displacement to express the RMF distribution are used for investigation of repeatability and stability. Results show that domain wall displacement is repeatable and stable both under cyclic stress round and during relaxation time after release of stress. It has been found that the situation of domain rotation is varied in different locations, and broad texture area of domain wall images has better repeatability and stability when compared with area with narrow texture of domain wall images. The results provide substantial potential to evaluate the residual stress from the view of characterization of micro-structure.