Study On Texture And Microstructure Evolution Of Grain-oriented Silicon Steel By One-Stage Rolling

Grain-oriented silicon steel has excellent magnetic properties and low iron loss.It is mainly used for iron cores of various transformers and is an indispensable soft magnetic material in power electronics and military industries.High magnetic induction grain-oriented silicon steel(Hi-B)is a Goss crystal nucleus with extremely high orientation sharpness by one stage cold rolling at a heavy reduction ratio,and obtains better performance and properties after secondary recrystallization.Heavier cold rolling reduction has an adverse effect on the microstructure and texture distribution of the recrystallization process,and it makes the control difficulty increased significantly.Adjusting the matching relationship between the cold rolling reduction ratio and the initial microstructure before rolling is an effective way to optimize the above problems.In this paper,Fe-3wt.%Si was used as the research object.The composite inhibitor system of MnS+AlN was used to treat the hot-rolled sheets with different initial thickness by one stage cold rolling of 84%,87%and 90%,in order to obtain the thickness 0.3mm of cold rolling.The cold-rolled sheet is subjected to different normalization treatments for the initial hot-rolled sheet corresponding to the cold rolling reduction ratio of 90%to optimize the microstructure and texture distribution.Subsequently,decarburization,nitriding,slow heating and high temperature purification annealing were performed,and a high magnetic induction grain-oriented silicon steel strip was successfully prepared.The evolution of microstructure and texture during the deformation,primary recrystallization and secondary recrystallization of grain-oriented silicon steel under large variables were characterized in detail,through metallographic microstructure,X-ray diffraction and B-H magnetic detection.The obtained results show are as follows:(1)Within the range from 84%to 90%of cold rolling reduction used in this study,with the increase of reduction ratio:γ texture with {111}<112>as the strong point strengthens gradually in the primary recrystallized matrix.And the proportion of the remaining texture components is relatively reduced;the grain size of the primary recrystallization is gradually reduced;the stability of the primary recrystallization structure is deteriorated at the reduction ratio of 90%,and the normalization system needs to be improved to optimize the organization and performance of the finished products.(2)The normalization system corresponding to the cold rolling reduction ratio of 90%was studied,and normalizing annealing treatments of 975℃,1025℃ and 1075℃ were employed.With the increase of the normalization temperature,the average grain size of the primary recrystallization gradually increases,and the grain size uniformity increases firstly and then weakens;the primary recrystallization structure stability can be optimized at the normalization temperature of 1025℃.(3)Through the study on the influence of cold rolling reduction ratio,it can be found that the reduction ratio of 87%has a good matching relationship with 975℃ normalization treatment,and secondary recrystallization is more perfect,and magnetic induction intensity is B8=1.95T;when the reduction ratio is 90%and the normalization temperature is 1025℃,it has a good matching relationship.At this time,the secondary recrystallization has a high degree of perfaction,and the magnetic induction intensity is B8=1.88T.