Half Process-oriented Electrical Steel Testing And Research

According to the practical process of electrical steel of Hunan Valin Lianyuan Iron and Steel group,the influences of deformation behavior and annealing treatment on the microstructure and properties of non-oriented electrical steel are discussed in four parts.In the first part,the isothermal constant strain hot compression behavior was studied by Gleeble-1500 thermodynamic simulator.The microstructure evolution during the hot deformation process was studied and the flow stress model was established.In the second part,the accuracy of the equipment(Epstein frame),especially nonstandard epstein frame,used to measure the magnetic properties of non-oriented electrical steel was investigated.In the third part,the evolution of the microstructure and the magnetic properties under different annealing process was studied.The optimum annealing process was established.In the final part, the type of inclusions and their influence on the magnetic properties of non-oriented electrical steels were investigated.By the above research,the following conclusions were obtained:1)The stress level factorα,stress exponent n,structure factor A and hot deformation actviation energy Q are calculated by hyperbolic sine Arrhenius model containing temperature and activation energy.The results are conformed with the experiment data.Therefore hyperbolic sine Arrhenius can be used in flow stress of hot plastic deformation of electrical steel.The constitutive equations of hot-rolling slab and casting-rolling slab of semi-process electrical steel need subsection construction.When the deformation temperature is in 500-800℃,to casting-rolling slab,stress level factor of is 0.039MPa^-1,stress exponent is 7.93,structure factor is 1.571s^-1,and hot deformation activation energy is 334.8kJ/mol.But when the deformation temperature is in 1050-1200℃, stress level factor of is 0.1258MPa^-1,stress exponent is 5.29,structure factor is 1.03s^-1,and hot deformation activation energy is 769.9kJ/mol.To hot-rolling slab,when the temperature is in 500-800℃,stress level factor of is 0.037MPa^-1, stress exponent is 9.37,structure factor is 41.1s^-1,and hot deformation activation energy is 329kJ/mol.But when the temperature is in 900-1100℃,stress level factor of is 0.106MPa^-1,stress exponent is 5.97,structure factor is 43.5s^-1,and hot deformation activation energy is 505.8kJ/mol. 2)The Samples of semi process electrical steel were prepared according to national standard((GB/T 3655-92).The magnetic properties of samples were measured by Epstein frame on TYU-2000M.The results shown that equipment of TYU-2000M can measure the magnetic properties of smei process electrical steel accurately.3)During the hot processing of semi-process electrical steel sheet,α-Fe recovery,recrystallization and grain growth took plcae.Meanwhile,α-Fe←�'γ-Fe transformation as well as dissolution and precipitation of soluble phase AlN and MnS were also occurred during that process.Excellent magnetic properties can be obtained by controlling grain size and homogeneity,texture orientation and dislocation density.Therefore,high heating rate,high temperature annealing and short holding time are beneficial to get non-oriented electrical steel sheet with low-cost and excellent magnetic properties.4)When annealing temperature was lower than the temperature ofα-Fe←�'γ-Fe transformation,with the temperature increased,the amount of {111}<112> texture declined,but {001}<100> texture amplified as well as Goss texture.When the annealing temperature is higher thanα-Fe←�'γ-Fe transformation temperature,the amount of {111}<112> texture,{111}<110>texture,{001}<100>texture and Goss texture declined significantly,but {111}<112> and {111}<112> texture raised when the temperature wsa too high.{111}<112> and {111} <112> texture decreased and Goss texture increased slightly with the increasing of heat up rate.5)The samples in this test are pure to some degree,but some inclusions, which are mainly Al₂O₃ sphericial particles and some Al₂O₃ containing SiO₂,CaO,FeO,Fe₂O₃,MnS,make component and structure asymmetric.Therefore,non-oriented electrical steel with excellent magnetic properties can be obtained by controling the amout of inclusion,heat treatment process,the grain size,grain homogeneity,orient and density of texture,dislocation density, precipitation of phase.More work should be done to ehance the magnetic properties of non-oriented electrical steel.