Study On Mechanical Properties And Subtractive Milling Properties Of Nickel-based Superalloy Fabricated By Directional Energy Deposition

Nickel-based superalloys have a wide range of applications in aerospace,highperformance turbines and other fields because they still maintain excellent mechanical properties at extremely high temperatures.However,Nickel-based superalloys prepared by directional energy deposition are typical difficult-to-cut metal materials,and there are currently few studies on the controlling mechanical properties and milling properties of Nickel-based superalloys prepared by directional energy deposition,so this paper mainly carries out research on the mechanical properties and milling properties of Nickel-based superalloys prepared by directional energy deposition.The additive manufacturing process mechanism of directional energy deposition Nickel-based superalloy and its milling process mechanism are studied through simulation software.Experimental research on the process parameters of additive manufacturing of directional energy deposition Nickel-based superalloys is carried out.The microstructure and mechanical properties of additive manufacturing Nickel-based superalloys are evaluated and the performance differences of subtractive milling performance between directional energy deposition Nickel-based superalloys and ordinary forged Nickel-based superalloys are analyzed.Based on the experimental research in this paper,it is conducive to the precise control of the mechanical properties and subtractive milling properties of Nickelbased superalloys by controlling laser processing parameters,prolonging the life of subsequent machining tools,and facilitating the further application of directional energy deposition Nickelbased superalloys.The research carried out in this paper is as follows:Studies on simulation of additive manufacturing process and subtractive manufacturing of Nickel-based superalloys fabricated by directed energy deposition are conducted.Based on ANSYS Workbench software,the simulation models of single-channel and multi-channel additive manufacturing of Nickel-based superalloy are established,and the deformation and residual stress of the additive-manufactured Nickel-based superalloy structural components under different additive process conditions of scanning speeds,hatch spacing and layer thickness are calculated by simulation software,and the location of the maximum deformation and the distribution of residual stress are analyzed.Simulation study of subtractive cutting process of Nickel-based superalloys for directed energy deposition is carried out,and the model is hypothesized based on the microstructure of Nickel-based superalloys(uneven structure including isometric grains and columnar grains)obtained by additive forming experiments.The results show that the height of the single-channel deposition decreases with the increase of laser power and increases with the increase of scanning speed,the width of the single-channel deposition increases with the increase of laser power,and does not change significantly with the increase of scanning speed,the error between the simulation data and experimental data is small,thus the credibility of the single-channel deposition model is high;the maximum residual stress of the multi-channel deposition is located in the joint part of the deposition layer and the substrate and the four apex angles of the substrate,and the residual stress of the multi-channel deposition increases with the scanning speed and decreases with the layer thickness.As the scanning speed increases,the residual stress increases first and then decreases.Due to the difference in microstructure,the machined surface morphology of the subtractive cutting of the additive-manufactured Nickel-based superalloy and the ordinary forged Nickel-based superalloy is obviously different,and the isometric grains region near the columnar grains will produce obvious plastic deformation,and the isometric grains region near the columnar grains produces a large residual stress,the cutting force of the isometric grains region of subtractive cutting is larger,and the cutting force of the cutting columnar crystal region is smaller;the cutting force of the additive-manufactured Nickel-based superalloy and the forging Nickelbased superalloy increases with the increase of cutting speed,under the same cutting speed.Nickel-based superalloys obtained by additive manufacturing have greater cutting forces for subtractive processing.The influence of directed energy deposition processing parameters on the microstructure and mechanical properties of Nickel-based superalloys is studied.The influence mechanism of laser processing parameters on the microstructure and mechanical properties of Nickel-based superalloys for directed energy deposition is analyzed.The influence of five laser process parameters of laser power,scanning speed,hatch spacing,layer thickness and forming direction on the microstructure and mechanical properties of Nickel-based superalloys prepared by directional energy deposition is investigated by single-factor experimental method.The mechanical properties of Nickel-based superalloys obtained from directed energy deposition and ordinary forged Nickel-based superalloys are obtained.The results show that the laser processing parameters affect the microstructure of Nickel-based superalloy in the form of laser energy density.With the increase of laser energy density,the cooling rate G×R decreases,the grain growth time is prolonged,the anisotropic columnar grains continue to grow along the deposition direction,and the grain size increases,so that the tensile strength,hardness and other mechanical properties are reduced,and the plasticity is improved along the deposition direction;in the five laser process parameters,the laser power and forming direction have a significant impact on the mechanical properties of Nickel-based superalloy fabricated by directional energy deposition,while scanning speed,hatch spacing,layer thickness have little effect on them.The tensile strength and hardness of the Nickel-based superalloy fabricated by directional energy deposition decrease with the increase of laser power,increase and decrease with the increase of scanning speed,increase and decrease with the increase of scanning spacing,first increase and then decrease with the increase of layer thickness,decrease with the increase of forming angle;the plasticity of Nickel-based superalloy fabricated by directional energy deposition decreases with the increase of laser power,first increases and then decreases with the increase of scanning speed,first increases and then decreases with the increase of hatch spacing,first decreases and then increases with the increase of the layer thickness,increases with the increase of the forming angle decreases;there is a large number of Laves phase segregation in the microscopic structure of the Nickel-based superalloy obtained by directional energy deposition,so that its hardness is reinforced and the plasticity decreases;compared with the ordinary forged Nickel-based superalloy,the tensile strength of the Nickel-based superalloy obtained by the directional energy deposition is reduced by 7.64%,the hardness is increased by 23.55%,and the plasticity is reduced,so the preparation of Nickel-based superalloy by the directional energy deposition process can ensure both mechanical properties and processing efficiency.The influence of directed energy deposition process parameters on the milling performance of nickel-based superalloys is studied.The influence mechanism of laser process parameters on milling force,milling temperature,surface quality and cutting chip form of Nickel-based superalloy fabricated by directed energy deposition is analyzed.The influence of five laser process parameters of laser power,scanning speed,scanning spacing,layer thickness and forming direction on the milling force,milling temperature,processed surface quality and cutting chip form of Nickel-based superalloy fabricated by directed energy deposition is tested by single-factor experimental method.Based on the previous research on additive manufacturing process and subtractive milling process of Nickel-based superalloy fabricated by directed energy deposition,the automobile double wishbone suspension hem arm mounting fork of Nickel-based superalloy is processed by additive-subtractive hybrid manufacturing method.The results show that the milling force decreases with the increase of laser power,increases with the increase of scanning speed,scanning spacing and layer thickness,and the milling force at the forming angle of 90° is greater than the milling force when the forming angle is 0°;the milling temperature decreases with the increase of laser power,and increases first and then decreases with the increase of scanning speed,scanning spacing and layer thickness,and the milling temperature at the forming angle of 90° is greater than the milling force when the forming angle is 0°;the roughness of the processed surface decreases with the increase of laser power,increases with the increase of scanning speed,layer thickness and hatch spacing,and the milling force of the machined surface roughness when the forming angle is 90°is larger than the milling force when the forming angle is 0°;compared with the forged nickelbased superalloy,the nickel-based superalloy obtained by the directional energy deposition has a greater milling force,a higher milling temperature and faster tool wear,but the processed surface roughness is lower,indicating that the nickel-based superalloy obtained by the directional energy deposition is more difficult to process,which is because there are more segregation of the Laves phase to increase the hardness and plasticity Nickel-based superalloy automobile double wishbone suspension hem arm mounting forklift parts processed by additive and subtractive hybrid manufacturing meet the requirements of use,and the parts have good dimensional accuracy and surface quality.