The Study On Cold Rolling Deformation And Recrystallization Of Pure Vanadium

The microstructures of body-centered cubic(BCC)metals after the deformation are complicated,and its' deformation mechanism and microstructure structure are relatively fragmented.Pure vanadium is a kind of BCC structural material,which has good mechanical properties.However,there are few studies on the deformation mechanism and recrystallization behavior of pure vanadium.In this paper,commercially pure vanadium(99.9%)was used as the starting material,samples were prepared by different rolling deformation.The samples were annealed under vacuum condition,annealing was carried out at different times to analyze the recrystallization behavior of the pure vanadium.Optical microscope(OM)and electron backscatter diffraction(EBSD)were used to analyze the microstructure evolution of pure vanadium under different cold rolling deformation and the recrystallization behavior during the annealing process.As the original sample is similar to the columnar crystal,grain size is very large,in order to obtain statistical data,so we need to analyze multiple samples.(1)The original sample of pure vanadium is similar to the columnar crystal structure,the grain size of section direction is 300?m,the grain size of columnar direction is millimeter;the original sample has good mechanical properties,the tensile strength is more than 200 Mpa,Breaking elongation is more than 60%.(2)Pure vanadium in the rolling process,different deformation makes the deformation mechanism different.The main deformation in the low strain is carried out by the rotation of the lattice and dislocations slip.Under medium strain condition,deformation is mainly carried out by the slip,shear deformation and lattice rotation of the dislocations,lattice rotation contributes less to deformation.The deformation is mainly composed of dislocation slip under the large strain condition,and the shear zone is broken and broken due to the dislocation slip.(3)The deformation of pure vanadium in the rolling process is non-uniform,even under the 90% deformation conditions,the deformation of pure vanadium is also concentrated in the vicinity of the shear zone,dislocations entangled around the shear zone;we observed the deformation Some areas is very small,deformation in these area is mainly through the lattice rotation,the dislocation density is very small.When deformation reaches 30%,the shear band is observed,with the increase of the deformation,the angle between the shear zone and the RD direction decreases gradually,and several different orientation shear bands are formed under the large deformation condition.(4)Because of the non-uniform deformation of pure vanadium,when the deformed samples annealed,the order of recrystallization nuclei is not consistent,and the equiaxed grains obtained by complete recrystallization are not uniform.The shear zone formed during the deformation process follows a certain orientation,So the recrystallized grains are also growing along the direction of the shear band during the growth process,but there is no apparent orientation after the complete recrystallization.