Elevated Temperature Deformed Behavior And Numerical Analysis Of Material Under Field

The study of electric field in metal deformability originated from electroplastic effect which was discovered in 1963. Troitskii et al found that the high density pulse current, when passing through the metal, could improve the plasticity and the toughness of the metal and decrease the deformation resistance. An external electric filed is considered to contribute to the improvement of the metal plasticity. The basic theory of these phenomena is the electric current or the electric field can take some effects on the material mobility (Including the vacancy, the dislocation and the interstitial atom etc of the metal).To solve these problems in electric field researches, this paper mainly studies on the principle of material mechanical properties under the different electric field strength and the microscopic mechanism of such effect.The author studied the electroplasticity mechanism of pure aluminum in elevated temperature, including mechanical properties and fracture etc. In addition, the author studied the effect of dislocation in pure aluminum elevated temperature deformation under the electric field by means of dislocation etch pit. When under the different electric field strength during experiments, the flow stress of specimens decrease as the electric field strength increased. Through analyzing of microstructure, the experiment indicates that the electric field could enhance the material mobility and the dislocation migration and suppress the cavity formation and the growth.Titanium alloy shows a negative electroplasticity under the electric field, which means the electric field increases the deformation resistance and decreases the plasticity. Through analyzing of microstructure, the experiment indicates the positive electric field reduces theβphase at the same temperature deformation. Grain boundary with theβphase deficiency makes the equiaxedαphase deformation difficulty. Dynamic recrystallization was suppressed under the positive electric field during the superplasticity deformation and the grain couldn't equiaxed in time during the deformation, which results in the grain couldn't coordinate during the superplasticity deformation and the electric field improve flow stress and decrease plasticity.Finite element (FE) analyses for superplasticity blow forming process are performed by using the ABAQUS. Through comparing analyses forming, with and without the electric field respectively, we found that the thickness of parts is more uniform under the strong electric field. This is the result of the strong electric field, which decreases the strain rate sensitivity exponent m of the materials and also makes the most equivalent strain decrescent at the corner, decreases the tendency of broken. The analysis gives some reference advice and better understanding in further practice.