Mesoscopic Simulation And Experimental Study On Selective Laser Melting Of Aluminum Alloy

In this paper,a three-dimension mesoscopic model was established using the finite volume method(FVM)to investigate the process of powder-to-solid transition under different processing parameters during selective laser melting(SLM)of AlSi10 Mg powder,taking account of the initial feeding powder material and the attendant significant complexity of the physical interaction between powder and laser beam.The effects of different laser power P(150W,200 W,250W,300 W,350W)with fixed scanning speed v(400mm/s)on the temperature field,velocity field,surface morphology and Z-direction shrinkage were also studied.It was found that both a high and a low laser power resulted in a rough surface quality.In order to verify the reliability of the model,cubic samples with a length of 5mm were prepared by the experimental method.The experimental findings were compared with simulation results and it showed good agreement.In order to study the effect of laser scanning speed on the laser penetration depth,a multilayer powder bed model was established.The solid layer with residual porosity was used to simulate the machined layer,on which some powder particles were generated.In the simulation,the powder was melted at different laser scanning speed v(150mm/s,200mm/s,250mm/s,300mm/s,350mm/s,400mm/s)with the constant scanning power P(100W).It was found that as the laser scanning speed decreases,the laser penetration depth increases;the metallurgical bond between the powder layers becomes more stable.Meanwhile,the different scanning velocity brought the residual porosity with different morphology.By tracing the trajectory of the single bubble in the molten pool,it was found that the lower laser scanning speed favored the residual pores of the former layer to float to the current processing layer.As a result,the former layer is denser.Finally,the sample was printed with the same processing parameters as the simulation,and the microstructure and tensile properties of the specimen were measured.The results showed that the porosity of the specimen surface was higher than that of the inner part,the tensile strength of the surface is lower than that of the core in the test,and the result of the experiment proves the accuracy of the model.