Research On Forging Processing Optimization Of 8009Al/SiC_p Composite Piston Head

Compared with the other SiC particle reinforced aluminum matrix composites,as a result of the high volume fraction of very fine dispersoids phase Al12(Fe,V)3Si,the 8009Al/15%SiCp composite is satisfactory as lightweight material for power engine pistons due to its high wear resistance,low thermal expansion coefficient,and especially the high temperature resistance.Forging is one of the main manufacturing methods for components and parts processing and it can result in great variation of microstructures and performance under different forging conditions,so the research on forging technologies is of great significance.Hot compression tests of 8009A1 alloy reinforced with 15%SiC particle composite prepared by powder metallurgy(direct hot extrusion methods)were performed on Gleeble-3500 system in the temperature range of 400?550 ? and strain rate range of 0.001?1 s-1 The processing map based on the dynamic material model was established to evaluate the flow instability regime and optimize processing parameters,as well as combining with microstructural observation.Furthermore,based on the correlative experiment,this paper systematically investigated the hot compression characteristics of the 8009Al/15%SiCp composite and the deformation behavior of a large forging piece by finite element method in order to provide theory and guidance for the actual hot mold forge.The main results of this dissertation are as follows:(1)The flow stress of 8009AI/15%SiCp composites increased initially and after a peak stress kept a steady value as increasing strain,while decreased progressively after the strain of 0.5 at strain rate of 1 s-1.(2)The processing map of 8009Al/1 5%SiCp composites revealed a maximum efficiency of power dissipation corresponding to 16.5%in stable domain.The optimum processing parameters for hot working were identified to be temperature of 500?550 ? and strain rate of 0.001?0.02 s-1.Fine and homogeneous microstructure could be obtained at a relatively higher temperature and a lower strain rate domain.But particle/matrix interfacial debonding,particle crushing or particle cracking was found under the other conditions.(3)An isothermal compression FEM model for 8009Al/15%SiCp composite was established and the effect of different technological parameters on the deformation process and load-stroke curves was obtained by the numerical simulation.The distribution rules of the equivalent strain,equivalent stress and temperatures have been obtained at various deformation velocities,deformation temperatures and friction factors.The results show that the deformation process parameters have a very important effect on the metal fluidity.Therefore,it is helpful to improve the forming performance of the material by adopting proper process parameters.(4)According to the analytical results of DEFORM simulation,the verifying experiment was conducted at a temperature of 550 ?,a velocity of 0.2 mm/s,small friction factor,and qualified products can be obtained.