| New energy vehicle has its advantages of environmental friendly,saving and simple.Including hybrid electric vehicles(Hybrid EV)and electric vehicles(EV),which were in use and gave more choices to people.To be the core components of new energy vehicle,driving motor had received more attentions from researchers.Non-oriented silicon steel is one of the key materials in manufacturing of driving motor.It plays a huge role in the rotation of the motor.The magnetic performance determines the high-efficiency operation of the motor,and the mechanical performance directly affects running of the motor.For the application of non-oriented silicon steel in the new energy vehicles,scholars put forward to new research ideas in recent years,optimizing the magnetic properties of non-oriented silicon steel products while improving its mechanical properties,namely developing non-oriented silicon steel products with high magnetic induction,low iron loss,high strength and high toughness.Twin-roll strip casting is a green and sustainable technology using on the development of high-strength non-oriented silicon steel strip products,it can effectively control the magnetic properties,through adjusting the process to promote the strengthening of mechanical properties.Therefore,using thin strip casting technology develope high strength non-oriented silicon steel products has great significance.In this paper,3.2%Si non-oriented silicon steel had to be research object,by adding micro-alloying element Nb,using casting strip technology to produce non-oriented silicon steel casting belt,through hot rolling,cold rolling,annealing treatment,study on the variety of structure,precipitates and properties.The following results were obtained:(1)The As-cast structure was mainly columnar grains and a little equiaxed grains in the center.The columnar crystals have strong<001>//ND texture,and the equiaxed grains were dispersed;It founded AlN and MnS precipitate,the size distribution was between 100～150 nm,and part of NbC precipitates.(2)During hot rolling,the microstructure is refined,and the mainly columnar structure became equiaxed crystal.The surface layer of the hot-rolled strip is mainly composed of {100}plane texture,and the center layer has a lot of γ fiber texture.Rapid cooling after hot rolling suppresses the precipitation of NbC.(3)When the reduction ratio of cold rolling is 72.3%,a large number of shear bands are formed in the cold rolled sheet.With the increase of cold rolling reduction,the angle of deviation between the shear zone and rolling direction decreases,the shear bands was pressed into a nearly horizontal fibrous tissue.With the increase of cold rolling reduction,{223}<110>and {111}<100>textures were enhanced,and the cold rolling reductions of 80.6%and 89%had no difference in texture characteristics between the center layer and the surface layer.(4)At annealing temperature below 900℃,the {111}<112>texture increased and the｛111}<100>texture decreased with the annealing temperature increasing.After more than 900℃,the {111}<112>texture decreased,the {111}<100>texture increased,As the annealing temperature increases,the Goss texture increases.(5)The NbC precipitates are mostly circular.The average size was 6.9nm and the volume firaction was 0.016%after annealed at 750℃ for 5min.The NbC precipitates size increased with annealing temperature.The volume fraction of NbC precipitates increased at first and then decreased,and the average size of NbC precipitates at 800℃ was 8.6 nm.With increaseing of annealing time,the precipitates gradually grew but the volume fraction of NbC precipitates gradually reached maximum.Rod-like NbC precipitated after 30 minutes of heat preservation.(6)0.5mm thick cold-rolled plate obtained good performance after annealed at 800℃ for 2 minutes,P15/50 was 6.26W/kg,P10/400 was 46.74W/kg,B50 was 1.624T,Rp0.2 was 681.76 MPa.(7)0.35mm thick cold-rolled plate obtained good performance after annealed at 750℃for 5 minutes,P15/50 was 6.625W/kg,P10/400 was 37.27W/kg,Rp0.2 was 659 MPa. |
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