Investigation On Parameters And Properties Of Selective Laser Melting 316L Stainless Steel Composites

Compared with the conventional manufacturing method,The selective laser melting?SLM?additive manufacturing with a series of advantages and has been developed rapidly in recent years.Metallic materials produced via selective laser melting?SLM?additive manufacturing?AM?can offer comparable and sometimes superior mechanical properties to those produced by conventional manufacturing techniques.However,SLM-316L stainless steel material is hard to meet the requirements of some high-strength working environments.Therefore,in order to enhance the strength of 316L stainless steel,the process parameters and properties of different mass content of Al₃Ti powder added to the 316L stainless steel powder.It is well known that the selection of additive manufacturing process parameters?laser power,scanning speed,building direction?plays a crucial role in the performance of the material.Therefore,by changing the laser power and scanning speed to control the laser energy density,316L stainless steel materials with different process parameters were prepared,and their microstructure,defect formation and mechanical properties were studied.The results show that with the laser energy density increasing,the densification of stainless steel material increases first and then decreases;when laser energy density was between74J/mm³-222J/mm³),the porosity of SLM-316L stainless steel parts under 1%.On this basis,the mechanical properties of the samples prepared under the four optimal process parameters were tested under different loading conditions.The average tensile strength of SLM-316L stainless steel was 757 MPa and the yield strength was 640 MPa.The elongation was about34%,and its performance is better than that of the 316L stainless steel prepared by the traditional casting method.On the basis of the above process research,different mass percentages of Al₃Ti powder reinforced 316L stainless steel composites were prepared.The effects of different mass percentages on the microstructure and properties of the composites were investigated.X-ray diffraction analysis of the material revealed that when the mass percentage of Al₃Ti was 1%,the composites consisted of austenite and ferrite biphasic compared to SLM-316 stainless steel.The tensile strength and yield strength of stainless steel has increased by more than 20%,while the elongation has not decreased significantly.When the mass percentage of Al₃Ti is more than 2%,the composite material is ferrite single phase.With the mass percentage of Al₃Ti powder increasing,the tensile strength and yield strength of the material increase.When the mass fraction reaches 3%,the tensile strength and yield strength increase to 1261 MPa and1207 MPa,respectively,but the toughness of the material decreases.The elongation is only about 6%.It can be seen that the addition of Al₃Ti has a significant effect on the properties of316L stainless steel.In order to compare with that of the Al₃Ti,TiAl powder is directly added to 316L stainless steel and the structural and mechanical properties were tested.Since the melting point is higher than that of the 316L stainless steel material,the addition of TiAl leads to a decrease in the degree of bonding of the matrix material.When the mass fraction of TiAl is 1%,the material properties do not change significantly;when the mass fraction is 3%,the tensile strength of the material increases to 858 MPa,the elongation decreases to 28%,and a large number of holes and unmelted TiAl powder are observed in the tensile fracture.