Preparation And Properties Of TiC Particle Reinforced 316L Stainless Steel Composites By Selective Laser Melting

In recent years,316L stainless steel has been widely used in aerospace,medical,automotive and other fields due to its high ductility,corrosion resistance,high temperature resistance and biocompatibility.Due to the low hardness,low strength and poor wear resistance of 316L stainless steel,the application of 316L stainless steel is limited.In this paper,TiC particle reinforced phase and 316L stainless steel powder were used as raw materials,and TiC particle reinforced 316L stainless steel composites were successfully fabricated by SLM forming technology.The experimental parameters were investigated and optimized by controlling the variables.The relative density and surface porosity were used to study the effects of different process parameters on the forming properties of TiC/316L composites and the optimized process parameters were obtained.The tensile properties,fracture analysis,microhardness,tribological properties and surface morphology of TiC/316L specimens under different technological conditions were analyzed.The strengthening mechanism of TiC particles was explored,and the relationship between process-forming quality-microstructures-properties was established.The results show that:With increasing laser power and scanning speed,the relative density and porosity of TiC/316L specimens increase first and then decrease,and the transverse porosity is lower than the longitudinal porosity.When the laser power is 200 W and 0.6 m/s,the relative density of TiC/316L specimens reaches 98.52%,while the transverse and longitudinal porosity are the lowest,0.43%and 0.59%,respectively.In addition,with the increase of TiC mass fraction,the relative density of TiC/316L samples decreases and the porosity increases gradually.Scanning electron microscopy and energy spectrum analysis show that the interface between TiC particles and 316L stainless steel matrix formed has no obvious defects and holes.In addition,XRD phase analysis showed that only two phases of?-Fe and TiC were formed in TiC/316L composites,and no other new phases were formed.Tensile test results of TiC/316L specimens under different process parameters show that the tensile strength of TiC/316L specimens increases significantly with increasing TiC mass fraction.When TiC mass fraction is 6%,the maximum tensile strength reaches 1102.2 MPa,and the fracture strain is 14.21%.Compared with pure 316L stainless steel,the tensile strength increases by 41.5%.In addition,changing laser power and scanning speed has little effect on the tensile strength of 3wt%TiC/316L specimens.Analysis of the fracture surface of TiC/316L sample shows that the fracture surface presents obvious ductile fracture.The results of microhardness test of TiC/316L composites show that the change of laser power and scanning speed has little effect on the microhardness of TiC/316L composites,and the fluctuation range is small.However,the microhardness of TiC/316L composites increases with increasing TiC particle mass fraction.Among them,the microhardness value of pure316L stainless steel is 220.2HV,and the microhardness value of TiC/316L composite increases to 343.7HV as the mass fraction of TiC increases to 9%.In addition,in the tribological test,when the TiC mass fraction is increased from 0%to 9%,the wear rate of the TiC/316L composite is reduced from 2.705×10^-4mm³/N·m to 1.128×10^-4mm³/N·m The wear rate is reduced by 58.3%compared to pure 316L stainless steel.It can be seen that the addition of TiC particle reinforcing phase to the 316L stainless steel matrix can significantly reduce the wear rate of the material,thereby improving the wear resistance of the TiC/316L composite.