Hot-rolling Recrystallization And Precipitation Behavior Of Non-oriented Silicon Steel For New Energy Vehicles With Rare-earth High Nb-Ti

Non-oriented silicon steel for new energy vehicles is mainly used in the manufacture of iron cores for driving motors.Because the motor rotates at a high speed during operation,and the huge centrifugal force experienced by the rotation can easily damage the motor rotor,it is required non-oriented silicon steel used by new energy vehicles has excellent mechanical properties under the premise of ensuring high magnetic induction and low iron loss.However,the existence state of microalloying elements in steel for new energy vehicles and their influence on the relationship between structure,recrystallization and precipitation behavior are still lacking in a system.It is very important to study the structure and the second relative hot rolling,cold rolling and annealing process,of which hot rolling is the decisive factor in the production of electrical steel.A study was carried out on the solid solution of Ti?Nb elements during heating and the relationship between recrystallization and precipitation during hot rolling of non-oriented silicon steel for rare earth high niobium titanium new energy vehicles.It has certain theoretical significance to control the precipitation of each element in the actual hot rolling process of high strength non-oriented silicon steel in the future and to improve the magnetic and mechanical properties of the finished product.This paper mainly takes 2.13% Si?2.13%Al?0.15%Nb and 0.1% Ti as the composition system.using Gleeble-1500 D thermal simulator,scanning electron microscopy,transmission electron microscopy and other equipment,the effect of heating process on grain size and the state of existence of the second phase recrystallization behavior during high temperature thermal deformation and the relationship between recrystallization and precipitation behavior during hot rolling are studied.The main conclusions of this thesis are:(1)When the heating temperature rises from 1120? to 1200?,Nb?Ti redissolution increased by 5.843% and 7.66% respectively,the average grain size increased 243?m.When the holding time increases from 20 min to 60 min,compared with the billet,Nb ?Ti has increased by 5.328% and 8.083% respectively,the average grain size increased 334?m.Increased heating temperature and prolonged holding time,causes a large number of Nb?Ti elements to dissolve back into the matrix.The pinning effect on grain boundary is weakened,it is beneficial to the increase of grain size of experimental steel.(2)When the deformation temperature is 1100?,1050?,1000?,the whole experimental steel shows dynamic recovery characteristics and no dynamic recrystallization occurs during the single pass compression process.High Nb-Ti new energy automobile electric steel in the hot processing process,mainly for static recovery,it is difficult to recrystallize behavior.Under the same pressure,the increase of rolling temperature and the prolongation of holding time are beneficial to the refinement of microstructure and the occurrence of recrystallization.(3)At 1100?,1050? and 1000?,deformation 40%,with the decrease of temperature and the insulation time,the average size of the effluent increases,the surface density and the Nb,Ti precipitation.The compound precipitates ofniobium titanium carbon nitridee are the main precipitates in the hot rolling process.With the decrease of rolling temperature and the prolongation of holding time,the precipitates coarsened,the precipitates size increased,the nailings on grain boundaries weakened,the subgrains merged,the recrystallization degree increased and the microstructure was refined.