The Influence Of Jet Pressure On The Residual Stress Field Of Bearing Steel In Strengthening Grinding

Reinforced grinding is a new type of surface strengthening technology,which can improve the fatigue strength of the workpiece by forming a residual compressive stress layer on the surface.There is closely related the intensive grinding process and the surface residual stress.At present,in the research of the reinforced grinding technology,the research on the formation mechanism of the residual stress field is relatively weak,and the research on the residual stress is not comprehensive,so the further development of the technology is hinder.For this reason,this paper combines experimental measurement and finite element analysis to study the formation process of residual stress field on the reinforced grinding,and study the influence of different injection pressure on the distribution of residual stress field.Based on the theory of elastoplastic mechanics,the plastic deformation process of bearing steel during intensified grinding is discussed,and the theoretical model of residual stress field is derived.To analyze the forming mechanism of residual stress from the micro-structure,carry out the observation of microstructure by SEM scanning electron microscopy and metallographic microscope.And preliminary determine the depth of the residual compressive stress layer.A single steel ball and multiple steel ball simulation models is established to simulate the process of strengthening the residual stress field by the ABAQUS software.The accuracy of the theoretical analysis was verified and the influence of injection pressure on the residual stress field was analyzed.Finally,discussing the influence of the number of steel balls on the residual stress field,which shows that the effect of the multi-steel ball model is ideal.Discussing the feasibility of micro-hardness indentation method to measure residual stress on bearing steel surface,and the accuracy of indentation method is verified by X-ray method,which shows that micro-hardness indentation method can be used to study surface residual stress with jetting pressure changing.The intrinsic relationship between residual stress and micro-hardness along the depth direction is determined.And the variation law of residual stress along the depth direction is analyzed according to the micro-hardness value.Through the experimental measurement,the influence of the injection pressure on the residual stress field of the bearing steel was analyzed.When the injection pressure is at the0.3⁰.55Mpa,the residual compressive stress affected the layer depth(?5₀?is gradually deepening,increasing from 20?m to 100?m,and the surface residual compressive stress???is slowly increasing.When the injection pressure is at the 0.55⁰.75Mpa,(5₀ is constantly,and?is increase slowly.The greater the injection pressure,the greater the maximum residual compressive stress(?₈)).The position of the maximum residual compressive stress moves from the surface of the sample to the depth direction as the injection pressure increases,(5₈)is constantly increasing.In addition,this paper verifies the reference ability of the finite element simulation model by comparing the simulation results with the experimental results,which using the increase of residual stress characterization values.It is shown that the variation of residual stress with injection pressure in simulation is consistent with the experimental law.