The Influence Of Electromagnetic Field On Metal Flow Stress In Electroplastic Effect And Experimental Study

Electrically-assisted manufacturing(EAM)is a new manufacturing process which uses the effect of electro plasticity to improve the plasticity of materials.It has the advantages of low cost,energy saving and environmental protection.At present,there is still no perfect theoretical explanation for the electroplastic effect,which greatly limits the development of EAM technology.In this paper,the research on the theory of electroplastic effect is of great significance to promote the development of EAM technology.Firstly,this paper discusses that magnetic field can promote the proliferation and migration of metal dislocations,and then improve the plasticity of metal.In the process of metal stretching,the flow stress of metal can be reduced by applying pulse or alternating magnetic field,which is called magnetoplastic effect.Both the magnetoplastic effect and the electroplastic effect can reduce the metal flow stress.When the electroplastic effect occurs,it is often accompanied by a high-intensity pulse current,and the high-intensity pulse current will also produce a magnetic field with high magnetic induction(strong magnetic field).The interaction between the strong magnetic field and the electrons in the metal will lead to the pinch effect and magnetoplastic effect.Based on the above analysis,this paper studies the influence of electromagnetic field on the flow stress in the metal electroplastic effect from the perspective of pinch effect and magnetoplastic effect.Secondly,combined with the pinch effect theory and dislocation slip thermal activation theory,the functional relationship between current density and metal tensile strain rate is derived,and the micro process of metal flow stress reduction caused by current is discussed.The influence of magnetic field excited by high intensity pulse current on metal plasticity is theoretically deduced.Then,based on the theory of magnetoplastic effect,the influence of electromagnetic field on dislocation slip process in metal is analyzed.Combined with the change of activation energy and activation area caused by electromagnetic field,the functional relationship between strain rate and current density in metal tensile process under high intensity pulse current is deduced.Finally,the experimental study of the metal's electroplastic stretching process is carried out,and the reduction of metal flow stress under different pulse current density is measured.The experimental results are compared with the theoretical calculation results.It is proved that the electromagnetic field has a great influence on the metal flow stress in the process of plastic deformation.