Simulation Study On A Process Of ECAP Deformation For Ti6Al4V Titanium Alloy

The research on equal channel angular pressing(ECAP)of Ti6Al4 V titanium alloy is still in the laboratory stage,which is difficult to match with the existing industrial production.In the process of ECAP,product quality is closely related to die size parameters,process path,external force acting mode,process control parameters,process environment,etc.This paper is based on ECAP process.CAD modeling software is used to construct3 d geometric models with different model parameters.Deform-3D software was used for simulation calculation.The results show that the best plastic deformation uniformity is when the rotation radius of the central axis R is 7mm,the corresponding inner rotation radius is 2mm and the outer rotation radius is 12 mm.On this basis,different initial temperature,extrusion speed,friction factor and equivalent stress are simulated.And the influence of these factors on the equivalent strain,metal flow velocity and temperature in the extrusion process.The relationship influence on the size and distribution of equivalent strain could descripted as friction factor is best;extrusion speed is next;while initial temperature is worst.The relationship influence on the size of equivalent effect force could descripted as extrusion speed is best;friction factor is next;while initial temperature is worst.The relationship influence on the size and distribution of metal flow velocity in the sample could descripted as extrusion speed is best;friction factor is next;while initial temperature is worst.The relationship influence on the size and distribution of the temperature in the sample could descripted as extrusion speed is best;initial temperature is next;while friction factor is worst.The relationship influence on the size of the load value of extrusion could descripted as friction factor is best;extrusion speed is next;while initial temperature is worst.In this study,the optimal control value of friction factor should be close to 0.4,the optimal extrusion speed should be 5.0mm/s,and the temperature has little influence on the overall deformation.The optimum 3d mold structure parameters obtained by simulation were used to make the experimental mold with equal proportion.The 6061 Al alloy material with high plasticity at room temperature was selected to replace Ti6Al4 V titanium alloy for experimental study.The effects of back pressure,extrusion path,extrusion path and extrusion speed on extrusion deformation were studied.It is found that the back pressure,the rotation Angle of the second pass and the extrusion speed can all affect the deformation morphology and deformation uniformity.The back pressure extrusion method can avoid the surface crack initiation and reduce the uneven end warping deformation due to the channel shape.Applying back pressure or a second squeeze can increase the required load.The extrusion velocity has little effect on the load value.It is not recommended to use the method of back pressure or continuous multi-pass extrusion when the load limit provided is not high.Under the conditions of this study,the hardness of the obtained samples increased by nearly 20 HV compared with the original samples after the same channel angular extrusion,the section hardness of the sample is not affected by the factors of second extrusion,back pressure and extrusion speed.