Mesoscale Simulation and Experimental Verification of Single-track Surface Morphology in Stainless Steel Laser Powder Bed Fusion
Selective Laser Melting(SLM)is a complex additive manufacturing process that involves the melting and solidification of metal powders using a high-energy laser beam.The quality of the SLM process is influenced by various parameters such as laser power,scanning speed,scanning path,and scanning spacing.Changes in these parameters can lead to common defects such as pores,spattering,cracks,surface roughness variations,and balling phenomena.These defects,in turn,can affect the microstructure,surface morphology,and mechanical properties of the manufactured parts.To enhance the quality of laser-based additive manufacturing,extensive experimentation is required to test various parameter combinations and identify suitable process parameters that minimize defect formation.However,due to the rapid and dynamic temperature variations and gradients within the small molten pool during SLM,it becomes challenging to monitor and analyze its thermodynamic behavior through experimental means.As computer technology advances,numerical simulations at the mesoscale of powder interactions offer the potential to explore the heat and mass transfer phenomena involved in the laser-powder interaction.This,in turn,aids in understanding defect formation and evolution,optimizing SLM process parameters,reducing development time,and cutting down production costs.Performing single-track simulations can significantly reduce computation time while effectively capturing the morphology of the molten pool's free surface.Therefore,the objective of this research is to explore the fundamental principles of heat transfer and fluid flow in the SLM process through simulation.This exploration aims to provide reference guidelines for adjusting practical printing parameters,such as laser power and scanning speed,during the actual printing process.This endeavor contributes to a better understanding of the physical phenomena in SLM,ultimately optimizing print quality and efficiency.For this study,316L stainless steel was chosen as the research material.A random arrangement powder layer model corresponding to the actual powder size distribution was established using the Discrete Element Method-based simulation software,EDEM.The created mesoscale particle model was then imported into Flow-3D software,where additional development facilitated the incorporation of a laser heat source.This laser heat source interacted within the area where the metal phase and gas phase interface unit positions,enabling a dynamic 3D simulation of the powder particle melting process.The numerical simulation provided insights into the intricate processes of powder particle heating,melting,molten metal flow,splattering,and solidification during the movement of the laser.By simulating various combinations of process parameters such as laser power(40-150 W)and scanning speed(0.4-1.3 m/s),the surface morphology of the molten tracks was simulated and the different types of defects were analyzed.Subsequent single-track scanning experiments were conducted using the set of process parameters defined in the model.The substrate material,316L stainless steel,was chosen to match the powder composition,facilitating better bonding between the molten track and substrate surface.The results indicated that at a laser power of 150 W and a scanning speed of 400 mm/s,the stainless steel powder was effectively melted,leading to a continuous and smooth trajectory upon solidification.Increasing scanning speed or decreasing laser power reduced the heat input,resulting in defects such as balling and necking.The three-dimensional dimensions and morphology of the melt pool and melt track were observed and analyzed through single-track experiments,effectively verifying the accuracy of the numerical simulation and predicting the types of defects in the LPBF process.
laser powder bed fusionmelt pool flow316L stainless steelmesoscale simulationsingle-track
李岩、刘琪、李亚杰、李聚才、吴志生
展开 >
太原科技大学 材料科学与工程学院,太原 030024
山西电子科技学院智能制造产业学院,山西 临汾 041000
激光选区熔化 熔池流动 316L不锈钢 介观模拟 单道
山西省基础研究计划山西省重点研发计划山西省科技重大专项山西省高等学校科技创新项目Welfare Project of the State Administration of Quality Supervision
万方数据
维普
