Effect of Microstructure Changes on Deformation Resistance of Silicon Steel in Electrically Assisted Forming
The work aims to investigate the effect of microstructure changes on the deformation resistance of silicon steel in electrically assisted forming.Electrically assisted tensile experiment and static current comparison experiment were designed under different deformation conditions.The specimens were measured with electron backscattering diffraction(EBSD).The ef-fects of electrically assisted tensile forming(EAF)on grain feature,grain boundary feature and micro-defects of a Fe-0.5wt.％Si steel were investigated.The experimental results showed that the deformation resistance of silicon steel decreased significantly in EAF.Under the action of current,the grain size increased slightly.The parameters such as grain axis ratio,grain boundary curvature,and triple junction curvature significantly increased under the action of electric current,with a maximum increase of 11％in grain axis ratio,71％in grain boundary curvature,and 43％in triple junction curvature.Under the action of electric cur-rent,the geometrically necessary dislocation density and microscopic defect density decreased significantly,with an average re-duction of up to 94％.It is concluded that the deformation resistance of silicon steel is reduced by the changes of microstructures.The grain boundary spacing increases with the increase of grain size and grain axial ratio.With the increase of grain boundary curvature,the grain boundary migration ability and the ability to cross the microscopic obstacles are enhanced,and the migration rate of grain boundary increases.With the decrease of micro-defect density,the system free energy of the sample decreases and the plastic deformation tendency of the silicon steel increases.
silicon steelelectrically assisted formingdeformation resistancegrain boundary curvaturedefect density
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