Experimental Study On The Effect Of Pulsed Magnetic Field Annealing On Microstructure And Texture Of Non-oriented Silicon Steel

Non-oriented silicon steel,as an important soft magnetic material,is mainly used to manufacture the iron core of the generator and motor.There are clear requirements for the iron loss and magnetic inductionof non-oriented silicon steel in order to improve the efficiencyofconversiontoelectricity and reduce losses.The microstructure and texture of non-oriented silicon steel are crucial factorsfor iron loss and magnetic induction.In the production of non-oriented silicon steel,the annealing process can effectively improve the microstructure and texture of non-oriented silicon steel.The non-oriented silicon steel coldrolling recrystallized by annealing,which brings about grain growth and changes in texture to obtain better magnetic properties.After the primary annealing,the non-oriented silicon steel needed to be punched andcut to the right size before being utilized.And some of the microstructure deforms after punchingand produces other defects such as deckleedges.After the second annealing,surface defects and the magnetic properties of the product canbe both improved.Therefore,study on optimal heat treatment process has become a significant method to improve the properties of non-oriented silicon steel.As a new heat treatment method,magnetic field heat treatment can significantly improve the microstructure and texture of materials.Studying the action law of magnetic field in heat treatment can offer some innovative ideas for the heat treatment of non-oriented silicon steel.In this experiment,50W1000 non-oriented silicon steel cold-rolled and primary annealing were annealed in pulsed magnetic field,which was compared with that in the same annealing process without magnetic field.The changes of iron loss and magnetic induction after applying a pulsed magnetic field were investigated by magnetic property detection device,the size and distribution of microstructure were observed by using metallographic microscope,and the changes of macro-texture type and intensity were detected through XRD.The pulsed magnetic field was applied to non-oriented silicon steel during the primary annealing process.When the annealing temperature was 800 ℃ and the magnetic field intensity at 10 m T,the iron loss and the magnetic induction intensity were reduced or increased respectively by 7.17% and 0.12% compared with the ordinary annealing process without magnetic field.By analyzing the changes of microstructure and texture,it was found that the average grain size increased by 15.52%,which promoted the favorable texture{100}<001> and {110}<001>,suppressed the unfavorable texture {111}<112>.The effect still existedthough the annealing temperature reduced to 780℃.Applying different pulsed magnetic fields to the secondary annealing process of nonoriented silicon steel,the iron loss was reduced by 2.52% when the annealing temperature was 800℃ and the magnetic field strength was 10 m T compared to the ordinary annealing process without magnetic field.However,this accelerating effect disappeared when the magnetic field strength increased to 20 m T.By analyzing the changes of microstructure and texture under different magnetic field intensity,we can conclude that when the magnetic field strength was 10 m T and 15 m T,the grain size increased after secondary annealing,which promoted the favorable texture {100}<001> and {110}<001>,suppressed the unfavorable texture {111}<112>.The optimal magnetic field parameter for secondary annealing was 10 m T.When the magnetic field strength was 20 m T,the grain size was minimized after secondary annealing and the favorable texture {100}<001> disappeared.