Study On The Influence Of Process Parameters On The Extrusion Properties Of SiCp/2009Al Composites

SiCp/2009Al composites have excellent comprehensive properties and play an important role in the fields of weapons,automobiles,and aerospace systems.However,because the movement of particles and matrix is not coordinated,SiCp/2009 Al composites are prone to damage in the secondary processing.Based on the Zener-Hollmon parametric constitutive equation,the thermal working diagram of SiCp/2009 Al composite was established by power dissipation rate and Murty instability criterion,and the influence of different deformation conditions on SiCp/2009 Al composite was analyzed.The three-dimensional model of SiCp/2009 Al composites was established by Deform finite element software under macroscopic conditions.The influences of hot extrusion parameters and protection mechanism on the stress,strain,damage,and extrusion pressure of composites during extrusion were studied deeply.The main conclusions are as follows:In terms of hot extrusion parameters,the influences of extrusion Angle and initial temperature on the properties of composites were discussed.The results show that the maximum value of stress,strain and damage occurs at the die mouth.The extrusion Angle has little effect on the extrusion properties generated in the extrusion process.However,with the increase of extrusion Angle,both strain and damage decrease first and then increase.With the progress of extrusion,the extrusion pressure increases exponentially at first and then stabilizes within a certain range.When the extrusion Angle is 90°,the stability range of extrusion pressure is minimum.With the increase of temperature,the extrusion properties of the composite tend to be better.When the initial temperature is greater than or equal to450 ℃,the increase of temperature on extrusion properties decreases.In terms of protection mechanism,the influence of canned morphology and canned thickness on the extrusion properties of composites during extrusion was discussed.Under the protection of the can,the maximum stress,strain,and damage also appear at the die mouth.The stress,strain,and damage of no can,half can and bottom can almost linearly decrease.The stress,strain and damage of the half can are reduced by 4%,11% and 41%,respectively,compared with that of the bottom can,but under the same extrusion rate,the half can meets the extrusion requirements faster.When the thickness of the bottom can is optimized,the stress,strain and damage decrease first and then increase with the increase of the canned thickness,and the maximum value is distributed in a "bowl" shape.The best extrusion properties are achieved when the canned thickness is 70 mm.When the canned thickness increases by 10 mm,the extrusion pressure changes slightly.By comparing the extrusion morphology of the bottom can with the actual extrusion parts,the simulated extrusion morphology of the can is consistent with the actual extrusion morphology,which verifies the rationality of the extrusion finite element model to predict the hot extrusion properties and morphology of SiCp/2009 Al composites.The conclusions of each chapter have some reference value,which lays a good foundation for the actual hot extrusion SiCp/2009Al composite technology.