Research Of Temperature And Stress Distribution In GH536 Superalloy Selective Laser Melting

Selective laser melting(SLM),as an advanced additive manufacturing technology(AM),is well-known for its high forming ability by industry,especially in aerospace manufacturing and medical device manufacturing which have high value-added products.During the process of SLM,the laser action area undergoes dramatic and complicated metallurgy changes,forming a highly nonlinear distribution of temperature and stress,which has a direct impact on the dimensional accuracy,microstructure and defect formation of the final part.Therefore,by studying the changes of temperature and stress distribution in the process of SLM,it is helpful to understand the reason of the defects,to help improve the SLM processing,reduce the defects in the parts and improve the performance of the parts.In this paper,the temperature distribution of powder bed in the GH536 superalloy SLM process was calculated using a finite element model.This model is base on the ABAQUS finite element analysis software,considering the penetration effect of the laser on the powder and the state transition between the powder and the solid.The shape of the molten pool obtained from the temperature distribution is in good agreement with the experimental observation.The results show that as the laser power increases,the width,depth and length of the melting pool increase,and the melting pool tends to be slender.As the scanning speed increases,the width and depth of the melting pool decreases,while the length remains unchanged,and the melting pool tends to be slender.Based on the calculation results of temperature distribution,the stressdistribution on the surface of the powder bed and the large size part are simulated.The results show that the compressive stress occurs in the molten pool area during the SLM processing,The forming area shrinks and forms a tensile stress as the molten pool away.The cladding layer shows tensile stress at last.The residual stress of the cladding layer is larger near the substrate during the SLM process.The accumulated temperature is beneficial to reduce the residual stress of the forming part.Based on the numerical simulation results,the GH536 superalloy sample was prepared,and its melt pool morphology and microstructure were characterized.The residual stress of the cladding layer was measured.The experimental results are in good agreement with the numerical simulation.