Research On SLM Forming Quality And Process Optimization Of Nickel-based Superalloy

Nickel-based superalloys are widely used in high-temperature components of turbofan engines with the most stringent requirements on structural materials owing to its excellent high temperature-performance..Laser selective melting(SLM),as an efficient and highly flexible metal additive manufacturing technology,has the advantages of high forming accuracy,short forming cycle,and high material utilization rate.It can be used for the rapid and high-precision manufacturing of nickel-based superalloy components with complex structures.In this paper,the research on the SLM forming process for nickel-based superalloys is carried out.The interaction mechanism between the high-energy laser and powder materials is analyzed.The influence of the scanning strategy on the surface quality of the formed parts and the process parameters on the mechanical properties of the formed parts is studied.The SLM forming process is optimized and improved the overall quality of nickel-based superalloy SLM parts.The main contents and conclusions are as follows:(1)Study on the interaction mechanism between high energy laser and powder materials.Starting from the transmission and absorption of laser energy in the powder,the interaction mechanism between laser and powder is studied,and the sintering process of nickel-based alloy powder is analyzed.It is found that the laser energy density can be effectively adjusted by changing the laser-related parameters,thereby realizing the control of the surface pressure of the sample,improving the sintering density of the material,and improving the processing quality of the nickel-based superalloy.With the help of simulation tools,the design model was simulated and printed,the cause of deformation of the formed part was analyzed,and the error compensation was performed on the 3D model data to optimize the design model.(2)Research on the influence of scanning strategy on the surface quality of formed parts.Taking Inconel 718 alloy powder as the object,the influence mechanism of different laser scanning strategies on the forming quality of printed parts and the influence mechanism of the surface quality of different feature structures are studied.The results show that for the outer surface of the forming parts,the surface quality of the serpentine scanning strategy is the best,and the side surface quality of the spiral scanning strategy is the best.By combining two different scanning strategies,this paper proposes a composite scanning strategy for different feature structures,and its reliability is verified.(3)Study on the influence of technological parameters on the mechanical properties of shaped parts.Taking the forming performances such as density,microhardness and wear resistance as indicators,this paper studies the influence of laser power,scanning speed and scanning interval on forming quality.And the internal consistency of the influence rules of various parameters on various performance indexes of SLM formed parts is analyzed from micro and macro angles.The research results show that the density,microhardness and wear resistance increase with the increase of laser power,but after the power exceeds a certain threshold,the performance begins to decline.As the scanning speed and scanning distance decrease,the performance indicators of the shaped parts gradually improve,but they also have certain thresholds.(4)Research on laser selective melting process optimization.Based on the response surface method,this paper establishes a regression model of the forming quality of the sample,and analyzes the interaction of various process parameters on the density,microhardness and wear resistance of the formed part.Based on the multi-objective genetic algorithm,the model is optimized,and finally the Pareto optimal solution set of the process parameters of the shaped part is obtained.Through forming experiment,comparing the measured data with the predicted value of Pareto solution set,it is found that the density error is in the range of 2.3%~2.5%,the microhardness error is in the range of 4.2%~9.6%,and the wear rate error is in the range of 4.2%~11.4%.The errors are within the acceptable range,which verifies the reliability of the optimization results.And the optimization model has a guiding role in actual processing.