Study On Microstructure Characteristics Of Metamorphic Layer Of GH4169 Cut By PCBN Tools And Tool Wear Under High-pressure Cooling

Superalloy GH4169 is a difficult-to-process material that currently accounts for a significant portion of China’s heavy industry.The severe and demanding working environment places a high demand on the service performance and life of the workpieces.The micro-structure defects of the metamorphic layer on the machined surface are the principal cause of the poor surface quality of the workpiece.To improve the microstructure of the metamorphic layer and hence the service life of the workpiece.The microstructure characteristics of the metamorphic layer of GH4169 cut by PCBN tools and tool wear during high pressure cooling will be investigated in this work.To begin,the GH4169 cutting process is simulated and analyzed utilizing Third Wave AdvantEdge metal cutting simulation software,as well as simulation models developed under various cutting parameters.The cutting force,cutting temperature,residual stress,and strain field simulation data are examined to identify the influence of cutting speed,feed rate,cooling pressure,and flank wear width.It provides theoretical guidance for subsequent experimental research on microstructure characteristics.Secondly,a GH4169 cutting experiment with high-pressure cooling is performed using the single factor technique.Cutting forces during the experiment are collected and analyzed.When doing flank wear experiment,the tool is pre-grinded to the set value before cutting.Samples of workpieces corresponding to each set of parameters are obtained by slow wire cutting and prepared into metallographic samples.Qualitatively analyze the microstructure characteristics of the metamorphic layer on the cutting surface using the optical microscope,scanning electron microscope,energy spectrum analyzer,x-ray diffraction,and then compare it to the original structure of GH4169 to reveal the layer’s microstructure characteristics.Finally,based on the theoretical knowledge of material crystallography,EBSD technology is used to quantitatively analysis the metamorphic layers of machined surfaces under different cutting parameters.Explore the change trend of grain refinement,plastic deformation and stress throughout the depth of the workpiece section,as well as the effect laws of cutting speed,feed rate,and cooling pressure on microstructure parameters such as grain size and grain boundary orientation,will be discussed.The wear shape of the flank formed by cutting GH4169 with a PCBN tool are investigated.By integrating the tool wear form with the EBSD experiment findings,the impact of flank wear on the metamorphic layer’s microstructure characteristics on the cutting surface is studied.This section of research provides a theoretical basis for controlling the microstructure defects of the metamorphic layer.