Numerical Simulation On Extrusion Of 15%Vol SiC_p/8009Al Matrix Composite Prepared

Particle reinforced aluminum matrix composites have good performance in low density,low expansion,thermal fatigue,high specific strength and high wear resistance,and thus have been developed rapidly in the fields of aerospace,military,automobile,electronics and sports.Hot compression tests of the extruded SiCp/8009 aluminum matrix composites prepared by Powder Hot Extrusion were performed on Gleeble-3500 system in the temperature range of 400?-550? and strain rate range of 0.001s-1-ls-1.The rheological stress curves of the composites were established.And the finite element numerical simulation software Deform-2d was used to study the hot extrusion of SiCp/8009 aluminum matrix composites under different process conditions.The main findings are as follows:(1)The flow stress of SiCp/8009 aluminum matrix composites increases with the increase of strain at high temperature hot compressive deformation,and gradually increases after steady peak.The rheological stress decreases with the increase of the deformation temperature,and increases with the increase of the deformation rate,which shows the positive strain rate sensitivity.(2)The rheological behavior of SiCp/8009 aluminum matrix composites can be described by the hyperbolic sine relationship of Zener-Hollomon parameters.The deformation activation energy is 488.3853KJ/mol,and the flow stress equation is:?=3.13904 × 1028[sinh(0.016912?)]7.19022 exp(-488385.3/8.31T)(3)The temperature field distribution,the equivalent stress map,the equivalent strain map,the deformation rate vector and the stroke-squeezing force curve are obtained by numerical simulation of the positive extrusion of the pipe.Extrusion simulation results:During the extrusion process,the maximum temperature of the blank occurs in the die area of the deformation zone,the equivalent stress and the equivalent strain distribution of the blank deformation zone are not uniform,and the maximum equivalent stress occurs at the die die,The maximum equivalent strain occurs on the outer surface of the blank in contact with the die module.Extrusion velocity field distribution is not uniform,in the die die speed to reach the maximum.Squeeze the pressure first with the punch under the pressure gradually increased to a certain value began to decline,and then float up and down at a certain value.(4)The influence of the deformation temperature and the extrusion speed on the hot extrusion of the pipe is analyzed.The influence of the stress field,the temperature field and the pressing force is analyzed.With the increase of the extrusion temperature,the equivalent stress reduce the distribution of the more uniform,while the required reduction in pressure,taking into account the quality of products and die life,and finally choose a reasonable deformation temperature of 450?-500?.With the increase of the extrusion speed,the required pressing force increases,the maximum temperature of the material increases obviously,and the temperature rise is very large.Choose a reasonable extrusion speed of 0.3mm/s-0.6mm/s.(5)SiC particles reinforced aluminum matrix composites the positive and negative rheological properties of the matrix metals in the forward extrusion deformation cause SiC to enhance the rotation of the SiC particles.Hard and brittle SiC particles in the base metal with the uneven flow of movement,once can not be under the action of a large stress in the direction of the joint force will be broken.The SiC particles in the outer blank are more likely to be cracked than the central part.