Study On Material Properties And Friction Performance Of Stainless Steel Parts Fabricated By Selective Laser Melting

Selective laser melting(SLM),one type of metal addictive manufacturing technologies,is used to fabricate metal parts particularly with the complex structures.SLM has been widely used in many fields due to the efficient processing and stable quality,which provides possibilities of novel design and customized products.Due to the complicated heat transferring,pores are prone to be generated causing low densities and poor mechanical properties.There are many studies focusing on optimizing processing parameters to reduce porosity and improve the mechanical properties.On the other hand,tribological performance is also important for a SLMed part.However,the influence of surface pores on the lubricating performance,which affects friction and wear,has not been studied.In this study,various stainless steel 316L parts were fabricated by SLM using different exposure times.The material properties and lubrication performance were investigated.The main work of this paper are as follows:In the first chapter,the principle and application of SLM were introduced.The influence of processing parameters on SLMed samples and the reasons of pore formation were investigated.Based on the literature review of the related studies,the content of the thesis was presented.In the second chapter,the preparation of SLMed samples used in the study and experimental plans were introduced.The theoretical basis for the selection of contact conditions in lubricating tests was also discussed.In the third chapter,the material properties of SLMed samples fabricated by different exposure times as well as conventional manufacturing samples were analyzed in many aspects including microstructure,phase identifications,densities and hardness.The differences and reasons were discussed.In the fourth chapter,pin-on-disc tests were performed to investigate the friction and wear performance of different SLMed samples under mixed to hydrodynamic lubrication regimes.The influence of pores on lubricating behaviors and the mechanism were discussed.The wear performance of different SLMed samples under various contact condition was investigated.Finally,the research work and results were summarized.Future work was also discussed.