Simulation Research On The Key Process Of Laser Additive Forming Of 316L Stainless Steel Thin-walled Ring Parts

Laser additive manufacturing is one of the hotspots of current manufacturing technology.Laser additive manufacturing often uses alloy powder or wire as raw materials,which is melted and accumulated under the action of a high-energy laser beam to form components with complex shapes.Different from traditional subtractive processing,laser additive manufacturing is incremental manufacturing achieved through layer-by-layer deposition.The formed components can be directly put into use after post-processing.The production cycle is greatly shortened on the premise of ensuring the performance of the components,so it has become a research hotspot for many scholars.However,in the laser additive manufacturing process,the heat input is large,the melting process is complex,and many influencing factors have significant effects on the deformation and microstructure of thin-walled parts.The experimental research method is time-consuming,labor-intensive and costly,so this article uses simulation as the main method and experiment as the supplementary method to carry out research,focusing on the influence of laser power,scanning speed,scanning method and other factors on the temperature distribution,deformation and stress of laser additive manufacturing of 316 L stainless steel ring thin-walled parts.First,the theoretical basis of simulation for laser additive manufacturing of 316 L stainless steel ring thin-walled parts was explained in detail.The ANSYS workbench software was used to set the initial and boundary conditions reasonably based on the change of the material's thermal properties with temperature,and the APDL parameterized language commands were used.The Gauss heat source was loaded with flow and the "life and death unit" was used to establish a three-dimensional transient finite element simulation model of 316 L stainless steel ring thin-walled parts,and by comparing and analyzing the surface temperature measured by the infrared thermometer when processing 316 L stainless steel ring thin-walled parts and the temperature data of the finite element simulation under the same parameters,the validity of the simulation was verified.Secondly,the temperature field and stress field of the 316 L stainless steel ring thin-walled parts were analyzed by finite element simulation.The effects of different laser powers,scanning speeds and scanning methods on the temperature distribution,molten pool structure,deformation and stress are studied.It is found that the peak temperature,molten pool size,deformation and residual stress increase with the increase of laser power,and increase with the decrease of scanning speed;keeping the laser power and scanning speed unchanged,and only changing the scanning mode,it is found that the scanning mode has little effect on the temperature distribution,and the effect on deformation and residual stress has no obvious discipline.Finally,Based on simulation results,the forming experiment of 316 L stainless steel ring thin-walled parts was carried out.Observing its macroscopic morphology and metallographic structure,defects such as "sticky powder spheroidization",overmelting,and cracks appeared,and the causes of the defects were analyzed.After comparing the simulation optimization parameters with the experimental results,a set of optimal process parameters for the preparation of 316 L ring thin-walled parts is selected: laser power 800 W,scanning speed 6mm/s,and normal scanning mode.The finite element model established in this thesis can effectively simulate the temperature distribution,deformation and residual stress in the laser forming process with changes in process parameters,and by combining the experimental data,the key process parameters of the ring thin-walled parts are obtained,which provides effective guidance for the large-scale application of laser additive manufacturing of 316 L stainless steel ring thin-walled parts.