Study On The Effect Of Pulse Current Density And Application Direction On The Tensile Properties Of Ti-6Al-4V Alloy

Ti-6Al-4V titanium alloy had good strength,corrosion resistance,etc.,and was also the most typical and most researched titanium alloy,however,it had problems such as large deformation resistance,low room temperature plasticity,and serious work hardening,which limited its application to a certain extent.The current-assisted forming technology proposed in recent years can better improved the forming performance of titanium alloys,and it had become one of the current research hotspots.In the current-assisted forming process,how the current parameters affected the forming performance of the material,especially how the current direction affected the mechanical properties such as the flow stress of the material,there were still few reports.This paper designed related experiments to study the flow stress of Ti-6Al-4V titanium alloy under different current densities and different current directions,and revealed its influence mechanism through TEM analysis.Based on the experimental data,a constitutive equation considering the current density and current direction under the action of the pulse current was constructed,and the constitutive model was verified by the finite element method.By changed the angle between the direction of the current and the direction of the load,the law of the effect of different current directions on the flow stress of the material was determined.The difference of dislocation configuration under different current direction conditions was studied,when the angle between the current direction and the load direction was smaller,the dislocation distribution in the material grain was more uniform and the dislocation pile-up phenomenon was less.Its mechanism was that pulse current promoted dislocation slip in the direction of <-12-10>（0002）.The pulse current promotes the movement of atoms at the grain boundary,making the crystal grains have a tendency to rotate.The experimental data of uniaxial tensile mechanical properties under pulse current conditions,based on the JC model,by adding functions describing current density and current direction,the flow stress constitutive equation of Ti-6Al-4V titanium alloy under different current density and current direction conditions was established.In the ABAQUS finite element platform,the UHARD subroutine was used to apply the constitutive equation to the numerical simulation of the uniaxial tensile deformation process,the simulation results are consistent with the experimental results,which verified the validity and practicality of the model.