Research On The Forming Process And Mechanical Properties Of 316L Stainless Steel Reinforced By Lanthanum By Selective Laser Melting

316L stainless steel has good corrosion resistance,oxidation resistance and good formability,so it has a wide range of applications in aerospace,energy and chemical industries,but due to the lower surface hardness and friction wear properties of stainless steel,limited its further application.Meanwhile,the development of 316L stainless steel in the field of nuclear protection is limited by thermal stress factor,irradiation life and irradiation creep limit.In order to solve the above problems,the composite of stainless steel can be prepared by adding submicron lanthanum hexaboride to 316L matrix,so as to improve the comprehensive properties of the material.In this paper,LaB₆/316L workpiece was successfully prepared by Selective Laser Melting（SLM）,and the forming process and properties of LaB₆/316L workpiece were studied.The main research contents are as follows:（1）Lab₆/316L mixed powder material was prepared and its selective laser melting process was studied.The research shows that the change of laser power can make the density of Lab₆/316L parts increase first and then decrease,the porosity of formed parts decrease first and then increase,and the influence of scanning speed on Lab₆/316L parts is consistent with this.When the laser power is 140 W and the scanning speed is 1 m/s,the density of Lab₆/316L parts is higher,98.71%,the forming quality of the parts is better,the section is smooth,the density is higher,and no obvious pores appear.（2）The phase and microstructure of SLM forming LaB₆/316L workpiece were analyzed.Under the optimized process parameters,the grain of SLM forming LaB₆/316L workpiece was refined,with fine microstructure and uniform distribution.（3）The influence of process parameters on the microhardness of LaB₆/316L SLM forming workpiece was studied.Under the process parameters adopted in this paper,by changing the laser power,the microhardness of LaB₆/316L workpiece presents a fluctuating change,and its average value varies within 226～242 HV.By changing the scanning speed,the microhardness of SLM formed samples showed an obvious trend of increasing first and then decreasing,and its average value varied within207～237 HV.（4）Three kinds of LaB₆/316L workpieces with LaB₆ contents of 0 wt.%,0.05 wt.%and 0.1 wt.%were prepared by SLM forming technology to study the effect of lanthanum hexaboride enhancement on the properties of the sample.Due to the fine crystal strengthening and dispersion strengthening of the rare earth phase,the microhardness of the formed sample of LaB₆/316L stainless steel increased significantly,and increased with the increase of the content of lanthanum hexaboride.With the addition of lanthanum hexaboride reinforcing phase,the section elongation of LaB₆/316L workpiece decreased and the wear resistance improved obviously.The addition of LaB₆ will also significantly affect the corrosion resistance of 316L stainless steel.