Process Reseach Of Porous 316L Stainless Steel Laser Rapid Prototyping

316L stainless steel is one of the most widely used medical metal materials,which has excellent compressive strength,high wear resistance,good anti-fatigue strength and enough toughness.However,medical implants need good biocompatibility,especially low elastic modulus,while the young's modulus of 316 L stainless steel is more than 190 GPa,which is not compatible with human natural bone and can lead to the phenomenon of stress shielding,which cause the loosening and fracture of the implant.Therefore,it is very important to study how to reduce the young's modulus of 316 L stainless steel and improve its biocompatibility by introducing the porosity.This paper discussed the current research situation and development trends of preparation of porous materials by Laser Engineered Net Shaping(LENS).The model of temperature field simulation in porous forming process had been established.The porous structure was designed by the calculation of porosity and porous 316 L stainless steel specimens were prepared.At last,the surface morphology,mechanical properties and biological compatibility were studied through experiments.Specific research contents are as follows:First of all,establish the model of temperature field on porous cladding layer based on the analysis of LENS procedure.The variation of molten pool temperature has been analyzed by using the model.Besides,the model can realize the study of temperature field on different pores by changing parameters.Then,calculate target porosity of porous materials by Nelson formula and design the porous structure.After this,prepare porous samples with different pore size through LENS.On the basis of specimens,study the change rule of pore size under the condition of different design value,which can provide the experimental basis for the preparation of porous samples with suitable pore size.Finally,observe the microstructure of the specimens by metallographic test and measure their microhardness.Conduct compression performance test to research compression mechanical properties of porous samples with different pore sizes.Study the biocompatibility of porous 316 L stainless steel by apatite forming experiment.These experimental results show that the porous specimens by LENS grain finer,the hardness value is higher than the general casting;pore introduction effectively reduces the young's modulus of materials.Hydroxyapatite can generate in the pore surface and the porous material has good biological compatibility.