Research On Magnetic Domain Refinement Technology Of Hi-B Grain-oriented Silicon Steel For Transformer

Grain-oriented silicon steel,which is mainly used to manufacture transformers and generators,is the most important soft magnetic material used in the electric power industrial.And the high-end silicon steel product is the development direction of future steel manufacture.The laser magnetic domain refinement is an effective way to reduce the power losses of grain-oriented silicon steel,which has several features such as energy stability,high speed and high efficiency.The present paper shows the laser scribing experiments of grain-oriented silicon steel sheets were implemented to investigate the effect of scribing on core loss and magnetic domain.The obtained results are a basis for the development of high performance grain-oriented silicon steel.The relationship between the parameters of laser scribing and the core loss reduction as well as that between laser parameters and domain structure of grain-oriented silicon steel were carefully examined.The laser scribing experiment found that the width of magnetic domain of silicon steels all narrows down after laser scribing processing with different parameters,and the eddy current losses of silicon steel sheet also decrease,leading to the reduction of the core loss of silicon steel sheet.The results show that the average core loss reduction rate of grain-oriented silicon steel reaches a maximum value and then decreases while increasing laser power and scribing spacing,and it decreases while increasing laser frequency and scanning speed.For the micro-topography of nicks,the depth of nicks increased while increasing laser power,and decreased while increasing scanning speed.The laser frequency had little influence on depth of nicks.The optimized parameters of laser scribing are obtained(laser power of 4 W,scanning speed of 100 mm/s,laser frequency of 30 kHz and scribing spacing of 5 mm),by which the average core loss of grain-oriented silicon steel(Baosteel)can reduce 8%and the maximum reduction of core loss is 12%.The average core loss of grain-oriented silicon steel(POSCO)can reduce 8.71%and that of TISCO can reduce 9.17%.