Study On Removal Mechanism Of Inconel 718 By Cryogenic Turning

The high cutting temperature,fast tool wear and serious work hardening problems in the process of machining superalloy restrict the popularization and application of this kind of material to some extent.In recent years,with the rise of liquid nitrogen cryogenic cutting technology,it provides a new development direction for the cutting of high temperature alloy.This paper studies the mechanical properties of Inconel 718 under low temperature,constructs the material constitutive model under low temperature and high strain rate,studies the material removal mechanism through orthogonal cutting simulation and cryogenic cutting experiment,reveals the influence law of cutting parameters on surface integrity,and provides a theoretical basis for cryogenic cutting.The influence of low temperature on mechanical properties of Inconel 718 was investigated by low-temperature tensile test,low-temperature Hopkinson test and lowtemperature Hopkinson dynamic impact shear test,and the ductile brittle transformation of Inconel 718 was analyzed.Based on the dynamic mechanical properties of materials,the constitutive model of Inconel 718 at low temperature and high strain rate was modified,and cryogenic cutting simulation was carried out based on the constitutive model.The accuracy of the constitutive model is verified by experiment and simulation,and the temperature field and stress field in the cutting process are further analyzed.Chips with different cooling conditions were collected through cryogenic cutting experiments,and the macroscopic and microscopic shapes of chips were observed and analyzed by means of scanning electron microscope and ultra-depth of field microscope.The chip root was obtained by experiment,and the removal mechanism of the material was analyzed.The effects of cutting parameters and cooling conditions on surface roughness,surface residual stress and microhardness were analyzed by single factor cutting test,and the effects of different cutting parameters and cooling conditions on surface integrity were investigated.