Formation Mechanism Analysis And Prediction Model Of White Layer In Orthogonal Cutting Of AerMet100 Steel

Ultra high strength steel(AerMet100)has good fatigue and stress corrosion resistance,which is widely applied to manufacture important structural parts,such as carrier aircraft landing gear,aircraft rotor and rocket casing.The effect of stress and strain causes the change of micro-structure on the machined surface in the process of mechanical manufacturing,which has a seriously impact on mechanical and mechanical properties,and then influence fatigue resistance and service life of products.Therefore,it is necessary to research the formation mechanism of the white layer on the surface of high strength steel and predict the thickness of the white layer accurately.Aiming at ultra high strength steel(AerMet100),the formation mechanism of the white layer on the surface was discussed in this paper.A white layer analysis for orthogonal cutting and finite element simulation prediction model are established.The paper mainly work are as follow:Combining micro-structure observation,phase analysis,elemental analysis,hardness testing and residual stress analysis,white layer formation mechanism of AerMet 100 Steel in orthogonal cutting was studied,the report shows that comprehensive mechanism of phase change and plastic deformation is the cause of white layer formation,characteristic of high hardness and easy cracking in white layer area were also being verified.Based on forecast model of cutting force and temperature field,considering shear and ploughing,a mechanical stress field at workpiece was established.A novel methodology was proposed to evaluate the phase transformation temperature,which takes into account the comprehensive effects of stress,elastic and plastic deformation.And a function related to cutting temperature and phase transformation temperature is defined to determine the white layer thickness,finally an analytical prediction model for white layer thickness was established.Mechanical parameters of AerMet100 steel is demarcated by experiments,and finite element prediction model for orthogonal cutting on which self-adaptive mesh technique is applied.Comparing with the results of cutting force experiment,the accuracy of the finite element prediction model was verified.Extracting the curve of temperature,stress and strain energy density of workpiece surface layer,comparing the temperature distribution curve with the actual phase change temperature distribution curve to predict the white layer thickness in orthogonal cutting.In order to verify the white layer analysis and finite element prediction model based on phase transition mechanism,dynamometer and NI data acquisition system are used to collect cutting force data,and VK-H1 XVE is used to measure white layer thickness in micro-structure measurement.Then,the predicted values of analytical model and finite element prediction model are compared with the measured values of cutting force and white layer thickness,which verified the effectiveness of the model.Finally,effect of cutting parameters and tool geometric parameters on white layer formation were analyzed with the model.This work can be furt her applied to optimize cutting process parameters,improving surface integrity of workpiece.