Study On The Manufacture Of Grain-oriented Silicon Steel Based On Twin-roll Strip Casting

Grain-oriented silicon steel is a important soft magnetic material.But the manufacture process of grain-oriented silicon steel is lengthy and complicated,and it has excessive energy consumption and serious environmental pollution.Twin-roll strip casting is a near net shape forming technology of plate and strip with the integration of sub rapid solidification and rolling deformation.The technology can shorten the process and reduce the production cost significantly.In this paper,the manufacture was based on twin-roll strip casting and the composition design of extra low carbon under laboratory conditions.After the cancellation of hot rolling and decarburizing annealing,the evolution of microstructure,texture and inhibitors with different normalizing temperature and intermediate annealing temperature were comparative studied and the prototype steel strips were produced.Besides,grain oriented silicon steel was manufactured by using asymmetrical hot rolling and one stage cold rolling process.The main conclusions of this work are as follows:The difference of precipitation state of inhibitors led to different work hardening rate,inhibition,homogeneity of structure and texture distribution under different normalization process.Without normalization,the coarse {001} grains were more,and the grains of y-orientation and Goss orientation were less after annealing.After primary recrystallization,the coarse {001} grains remained and the inhibitors were small,so grain growth was not effectively inhibited,resulting in poor homogeneity and imperfect secondary recrystallization.As the normalization temperature increased,the amount of inhibitors,the ability of inhibition and the work hardening rate increased with normalization.Besides,the {001} texture was weakened,and the y texture and Goss texture were enhanced.The corresponding uniformity of cold-rolled strip,intermediate annealed strip and primary recrystallized strip was better,and the corresponding secondary recrystallization was more complete.The inhibitor components were MnS and AlN.The size of inhibitors was concentrated in 10?30nm,the amount of inhibitors and the particle size were larger when normalizing temperature was high.The recrystallization rate of oriented silicon steel in intermediate annealing process was different under different intermediate annealing process.As the intermediate annealing temperature increased,the recrystallization driving force of Goss texture and y texture after first cold rolling was enhanced,and the coarse grains of {001} orientation continuous recrystallized after deformation.Therefore,when the annealing temperature was high,the Goss texture can be better developed,the coarse grains of {001}orientation were broken and decomposed,and the corresponding uniformity of intermediate annealed strip,cold rolled strip and primary recrystallized strip was better.Secondary recrystallization was also more perfect.The inhibitor components were MnS and AlN,and the size of inhibitors was concentrated in 10?30nm,The temperature of intermediate annealing was higher,the amount of inhibitor precipitation was more,and the size of inhibitors slightly increased.As the temperature of hot rolling increased,the shear deformation of hot rolling was more severe,more Goss texture was formed,and coarse grains of {001} orientation are reduced under asymmetrical hot-rolling and one-stage cold rolling process.However,the coarse grains of {001} orientation were not effectively removed in the hot-rolling step under all kind of process conditions due to the limit of mismatch speed ratio and hot rolling reduction,and the cold-rolled reduction was consumed.As a result,the primary recrystallization was inhomogeneous and no secondary recrystallization occurred.The inhibitor components were mainly MnS.The amount of inhibitors was less,but the amount and size of inhibitors increased when the hot rolling temperature increased.Above results and analysis indicated that the primary recrystallization structure uniformity was one of the most important factors affecting the secondary recrystallization of oriented silicon steel.In this paper,the as-cast strip of coarse grains was used as the raw material.The coarse grain of {001} orientation was very stable,and it was difficult to deform and recrystallize during the processes.So it was easy to inherit to the primary recrystallized structure which prevented secondary recrystallization of Goss grains.It was found that increasing the normalization temperature and the intermediate annealing temperature could improve the uniformity of microstructure and make the secondary recrystallization more perfect.Asymmetrical hot rolling and appropriate hot rolling temperature could also reduce the influence of the coarse grains,to get more Goss texture.Therefore,this paper had provided a certain data support for improving the process parameters of grain oriented silicon steel and obtaining better control of micro structure and properties,which lays a foundation for further study of the manufacture of grain oriented silicon steel based on twin-roll strip casting.