Texture Evolution And Magnetic Properties Of W800 High Magnetic Induction Non-oriented Silicon Steel

Non-oriented silicon steel with high magnetic induction can effectively improve the efficiency and reduce the loss of motors,mainly used in the production of high efficiency motor products.The production technology has become a hot research in China and abroad.Currently Nippon Steel,Baosteel and other enterprises have been successfully developed high magnetic induction non-oriented silicon steel,the main technical means were using pure steel liquid,adding micro-alloy elements,normalizing treatment and stress relief annealing,etc.Some companies were also trying to develop it,but due to the limitations of raw materials and equipment,there still existed problems below:the liquid steel wasn’t pure,sulfur content was higher,no normalizing treatment furnace and no electromagnetic stirring.Based on these problems,this study aims to develop a new technology of high magnetic induction non-oriented silicon steel,which is suitable for the process of these enterprises through the composition design and process optimization.The specific research contents are as follows:(1)The evolution of microstructure and its effect on magnetic properties of micro alloying elements were investigated.Compared with ordinary W800 non-oriented silicon steel,the steel with antimony element has the smaller grain size of the coiling and annealing microstructure,and the favorable X,-fiber texture of the finished product were more,and the unfavorable y-fiber texture was weakened.When the coiling temperature was 750 ℃,the steel with Sb has the better comprehensive magnetic properties,the average magnetic induction(B50)increased by 0.01T,reached to 1.761T,the iron loss(P1.5/50)increased by 0.36W/kg,reached to 4.627W/kg.(2)The effect of finishing temperature on the microstructure and texture evolution were investigated.At low finishing temperature,the microstructure of hot rolled sheet was mainly deformed ferrite;at high finishing temperature,the microstructure of hot rolled sheet was recrystallized microstructure,the grain size distributions were relatively homogenous.High finishing temperature was conducive to reducing the harmful y-fiber texture and a-fiber texture of the hot rolling texture,coiling texture and cold rolling texture.After recrystallization annealing,the favorable λ-fiber texture decreased,but the y-fiber texture intensity decreased and the λ-fiber texture intensity was weaker,at the same time,the Goss texture appeared.(3)The evolution of microstructure and its effect on the magnetic properties of different coiling temperatures were investigated.After coiling at 650℃,the hot rolling deformation microstructure still preserved,but a large number of fine recrystallized grains appeared on the surface.After coiling at 700 ℃ and 750℃,fully recrystallization happened.The grain size of finished product was fine and uneven at low coiling temperature,it led to higher iron loss.When the coiling temperature was higher,the microstructure of finished product was more uniform,meanwhile,the grain size increased.Compared to not coiling,the y-fiber texture significantly weakened,X,-fiber texture increased after coiling.Compared to not coiling,the iron loss increased at the beginning and then decreased while the magnetic induction significantly improved with the coiling temperature increasing.Compared to not coiling,the average magnetic induction(B50)increased by 0.013T,while the average loss(P1.5/50)was reduced by 0.05W/kg when coiling at 750℃.It indicated that the coiling temperature is one of the key factors that affect the magnetic properties.(4)The evolution of microstructure and the effect of the precipitation of inclusions on the magnetic properties of different annealing atmospheres were investigated.When annealing in N2 atmosphere,the finished product exsisted a large number of fine AIN precipitation,inhibited the grain growth,as a result,the grains were fine and the uniformity was bad,and it led to the higher iron loss.When annealing in Ar atmosphere,the average grain size was about is about three times of that annealing in N2 atmosphere,it greatly reduced the iron loss.However,the magnetic induction was decreased,due to the increase of y recrystallization texture when annealing in Ar atmosphere.