The Study Of Ultra-Thin Non-Oriented Silicon Steel With High Magnetic Induction And Low Iron Loss Based On Twin Roll Strip Casting

Ultra-thin non-oriented electrical steel is mainly used for the iron core of high-frequency motor.It has been paid widespread attention,due to the low iron loss,high magnetic conductivity and low magnetic noise in medium-high frequency.The eddy current loss is proportional to the square of the thickness,therefore reducing the thickness of silicon steel sheet is an important method to reduce iron loss.But with the decrease of the thickness,the larger deformation leads to the deterioration of texture and the decrease of magnetic induction intensity during preparation of ultra-thin non-oriented silicon steel.Therefore,we tried to improve the final texture and the magnetic properties of the ultra thin non oriented silicon steel by changing the technological process of cold rolling and annealing based on the twin roll strip casting.The effect of cold rolling deformation and final annealing temperature on micro structure and magnetic properties of non oriented silicon steel were studied in this paper.The main contents and results are as follows:(1)The effect of cold rolling reduction on magnetic properties,microstructure and texture of ultra thin non-oriented silicon steel were investigated.With the increase of cold rolling reduction,α and γ fiber texture enhanced and recrystallized grain size became larger.α texture almost disappeared after annealing and forming the specific α’ texture.The intensity of γ texture and a texture reinforced,and the density peak of a texture gradually tended to {111}<112>.Iron loss reduced as the rolling reduction increased.But the magnetic induction intensity deteriorated because of the enhancement of y texture.(2)The effect of secondary cold rolling reduction on microstructure and magnetic properties of ultra-thin non-oriented silicon steel produced by two-stage cold rolling was investigated.Compared with the previous method one step cold rolling,the final recrystallized grain size increased significantly.With the increase of the reduction of the secondary cold rolling,the grain size decreased.γ texture and a texture also decreased gradually.Magnetic induction became lower by the reason of a texture of the favorable texture recede.Due to the large final grain size,the core loss increased and the iron loss will not only decreased,but also increased.The magnetic induction intensity is also lower.The iron loss and magnetic induction with 5%reduction is P10/400=13.173W/kg,B50=1.575T.(3)The effects of secondary cold rolling reduction on microstructure and magnetic properties were investigated.After secondary annealing,the grain size increases obviously.As the secondary cold rolling deformation is little,the storage can be lower,and the texture of the secondary annealing is more dispersed.The intermediate small deformation rolling eliminates the deterioration of texture and provides the conditions for subsequent optimization of texture.As the reduction increased,the final recrystallized grain size decreased gradually.Compared with first cold rolling method,the magnetic properties have been greatly improved.The magnetic induction decreases first and then increased,and the low-frequency iron loss gradually increased,and the high-frequency iron loss increased first and then decreased.The magnetic induction intensity B8 rangeded from 1.453 to 1.508,and B50 increased from 1.681 to 1.734.(4)The effect of the final annealing temperature on the texture and magnetic properties was investigated.The grain size of recrystallized grains increased and the core loss decreased with the annealing temperature growth.Both α and α’ texture decreased,instead favorable η texture increased with the increase of annealing temperature.Although the annealing temperature increased,the {111}<112>in the y texture decreased,but the{111}<110>texture increased,resulting in an increase in the proportion of the {111}texture and cause magnetic deterioration.