Performance Analysis And Optimization Of Laser Selective Melting 316L Stainless Steel Parts

Selective Laser Melting(SLM)technology is a promising and advantageous additive manufacturing technology,it can quickly and accurately produce parts of complex shapes based on 3D models.and it is widely used in automotive,aerospace,medical fields and so on.However,compared with manufacturing via conventional methods,the parts,formed through SLM,still existing such significant differences in some aspects as microstructure,performance,etc.Therefore,this paper takes stainless steel 316L powder as the forming material,and makes systematically studied on forming process and performance of SLM forming parts,aims to improve the performance of SLM forming parts.The main research contents are as follows:(1)According to the single-melt experiment,we established the single-melt forming process window,and analyzed the single-melt morphology and the evolution process of the molten pool.The results show that the wetting property of the formed powder is the main factors influencing the quality of single-melt forming.Then,through the single layer forming experiment,it provides a basis for the rapid acquisition of the process parameters of the block forming experiment.Finally,the orthogonal experiment was used to study the influence degree of different process parameters(laser power,scanning speed,scanning pitch and scanning strategy)on the upper surface roughness of SLM forming parts,are arranged as follows:scanning speed>scanning pitch>laser power>scanning strategy.(2)The influence of different process parameters(laser power,scanning speed,scanning pitch,laser energy density)on the performance of SLM forming parts was studied through single-factor experiments.the experimental results show that when the laser power is(250-350)W,the scanning speed is(400-600)mm/s,the scanning interval is(0.12-0.16)mm,and the laser energy density is(80-110)J/mm3,the 316L stainless steel powder is fully melted and has no over-melting phenomenon,and the formed melt channel is continuously flat and well-joined.The SLM formed parts have only a small amount of spheroidization,holes,micro-cracks,and incomplete fusion defects,and the density reaches 98%or more.And the upper surface roughness is less than 6 ?m.(3)The effects of different forming directions(X-Y horizontal forming,X-Z side forming,Y-Z vertical forming)on the mechanical properties of SLM forming parts were investigated by single factor experiments.The experimental results show that the mechanical properties of SLM forming parts are anisotropic.The tensile strength of SLM forming parts in different forming directions is as follows:Y-Z vertical forming>X-Z side forming>X-Y horizontal forming.The fracture mode of the formed parts mainly includes dissociation Brittle fracture and ductile fracture.(4)In order to further improve the surface quality of SLM parts,this paper uses laser remelting process to optimize the surface quality of SLM parts.After laser remelting,The upper surface and side surface roughness of the SLM formed parts were reduced by 66.67%and 33.33%,respectively.