Selective Laser Melting Of AlSi10Mg:Simulation And Experiments

Selective laser melting(SLM),one of the most important metal additive manufacturing technology,has been widely known due to the capacity of directly manufacturing parts with complex geometries from CAD models.Owing to the combination of its light weight and good mechanical properties,AlSi10 Mg has been widely used for automotive,aerospace industry,and other fields.However,it is difficult to manufacture the complex integrated AlSi10 Mg components free of any defects through SLM technology.In order to solve these issues,a 3D finite element model is established to simulate the temperature and stress fields during the SLMprocessed AlSi10 Mg,and to optimize the parameters to reduce the defects.Simulation results are confirmed through the corresponding experiment.The main work is as follows:Finite element model of SLM-processed AlSi10 Mg is established through ANSYS APDL software program.The powder–solid transition,temperature-dependent thermal properties,melt pool convection,and recoating phase are taken into account.Based on the model of SLM-processed AlSi10 Mg,the effects of exposure time(ET)and point distance(PD)on SLM thermal behaviour are also investigated.Results show that: the maximum temperature,the liquid lifetime and molten pool sizes rise as the ET increases or the PD decreases,but oppositely,the cooling rate reduces.The PD has more notable effects on the liquid lifetime and cooling rate of molten pool.Based on the results predicted by temperature field simulation,a stress field mode of SLMprocessed AlSi10 Mg is developed through thermal-structural coupling method to study the distribution and evolution of stress field,and effects of ET and PD on residual stress.Results show that: the maximum residual stress and the minimum residual stress gradually increase with the increase of ET.The maximum residual stress first increases and then decreases with the increase of PD,and while the minimum residual stress decreases.This is because the higher PD can lead to the poor overlap of the molten pool,and even the occurrence of unfused powder,reducing the residual stress.The experiments of SLM-processed AlSi10 Mg are also performed to validate the simulation results.The combinations of simulation and experiment are aimed at explaining the effects of ET and PD on roughness,molten pool morphology,defects and microhardness.It proves that the best forming quality-with high density and smooth surface-is obtained at the optimised combination of ET=140?s and PD=80?m.Besides,the roughness variation among different side faces is caused by the scan direction,gas flow direction,and wiper movement direction,appropriate rotation increments and parts orientation can effectively narrow the variation.