Research On Powder Forging Process Of High Performance Ring Parts

Iron-based powder metallurgy materials and parts are the main products of the powdermetallurgy industry,which are widely used in mechanical parts and automotive industry.But the iron-based parts produced by conventional pressing and sintering remain a certain amount of pores.It leads to lower strength,fatigue resistance and wear resistance,unable to meet the requirements of mechanical properties further.Development of powder metallurgy products with high density and high performance has become the development direction and research focus of powder metallurgy technology.Powder forging technology combines the advantages of traditional powder metallurgy with precision forging,which can significantly improve the density and mechanical properties of sintered parts.It is an important method for iron-based powder metallurgy densification.By combining numerical simulation with physical experiments,the powder forging process of a ring part on a car is studied.The compacting process of the iron-based parts and the influence of different forging process parameters on densification are analyzed.Finally high density and high performance powder forging ring parts are obtained.The research contents can be concluded as follows:(1)A powder forging process and a test die for a ring part are designed,and the numerical simulation of powder forging process is carried out.By analyzing the change of stress,strain,density and other fields,and the influence of forging heating temperature,forming speed,initial density of preform and friction coefficient on the density,providing guidance for the forging experiment.(2)The powder forging experiments of low alloy steel Fe-1.9Ni-0.5Mo-0.6C powder materials were carried out.The forged ring products with density of 7.63g/cm~3 and density of 98.5%were obtained,and their pore size and microstructure were analyzed.The results of the test are in good agreement with the numerical simulation results,and the reliability of the process design and numerical simulation analysis is proved.(3)High tungsten and high chromium iron based ring parts with density greater than7.3 g/cm~3 were prepared by sintering forging(S/F)and powder direct forging(P/F).The compacting effect,microstructure and mechanical properties of the two kinds of process are compared,and the powder forging process of this kind of material is further optimized.