Study On Recrystallization And Precipitation Behavior In Thin Continuous Casting Strip Of Middle-low Grade Non-oriented Silicon Steel

At present,the middle-low grade non-oriented silicon steels are mainly faced with the problems of overcapacity,but the high efficiency electrical steel still need to be imported.So,it is of great significance to improve the quality of the electrical steel and reduce the production cost.In this paper,the as-cast 1.3%Si non-oriented silicon steel strips and the conventional 0.4%Si non-oriented silicon steel hot rolled bands were taken as experimental materials.The effects of strip casting,rapid heat treatment,hot rolling and normalizing processes on recrystallization,precipitation,texture and magnetic properties were studied.The main conclusions are as follows:(1)The grain size of T14 as-cast strip produced by copper cast rollers is much less than G14 that by steel cast rollers.Compared with G14 as-cast strip,T14 strip has the larger energy storage,recrystallization nucleation rate and recrystallization speed.A large amount of second phase particles which dissolved into the T14 as-cast strip matrix would be precipitated and gathered during annealing,which prevented grain growth and deteriorated the magnetic properties.Besides,The larger grain size of as-cast strip was beneficial to obtain Goss and Cube texture after annealing,and further improved the magnetic properties.(2)In the process of rapid heat treatment,the higher treatment temperature could coarsen the existing precipitation and promote the precipitate behavior of second phase particles.In the process of slow heating,recrystallization rate would decrease with the extension of isothermal times.Rapid heating improved the recrystallization temperature and recrystallization rate,it also could promote the precipitation of second phase particles and conducive to the nucleation of Goss grains,increasing the percentage of {110} grain.(3)For the rolling technology of hot rolling plus cold rolling,the magnetic properties of final product were obviously improved by increasing the hot rolling temperature and reduction.Hot rolling could promote the precipitation of second phase particles and the existing particles would continually grew up during normalizing and annealing process.The fine particles significantly decreased in the final product,which was beneficial to the magnetic properties.With the increase of hot rolling reduction,{110} grains increased while the {100} grains reduced.At 950?,the magnetic properties of final product were best,the lowest value of core loss was 4.028 W/kg and the highest value of magnetic induction was 1.795T.(4)In the hot rolled sheets,the normalization process is beneficial to weakening the ?texture and enhancing the rotating cube {001}<110>texture.With the increase of normalizing temperature,the grain size of final product and precipitates size effectively increased,resulting in the low core loss and high magnetic induction of silicon steel.At the annealing temperature of 1000?,MnS had the largest nucleation rate and a large number of small MnS particles were precipitated,leading to the deteriorative magnetic properties of final products.