Establishment Of Constitutive Model For 06Cr18Ni11Ti And Experimental Study On Creep Feed Grinding Of Narrow Deep Grooves Of Such Material

Narrow deep groove is a special type of groove structure with width of groove to be less than 4mm and the ratio of the depth over the width(of groove)to be greater than 2.Such grooves are often used on some key parts in the aviation and automotive field.Generally speaking,there are 10~12 radial high precision straight grooves uniformly distributed along the rotor circumference.These grooves are typical narrow deep grooves.Machining narrow deep grooves of high precision has been proven to be challenging.Referring back to the rotor pump,when transporting corrosive material,rotor material must be a corrosion resistant material,such as 06Cr18Ni11 Ti austenitic stainless steel,which has not only higher ductility and toughness,but also good weld ability and strong intergranular corrosion resistance and is widely used in various fields of chemical industry and light industry.It has a certain theoretical significance and practical value to select 06Cr18Ni11 Ti as rotor material and machine narrow and deep grooves.In the first section of this paper,the study of the dynamic mechanical properties of 06Cr18Ni11 Ti was made.The quasi-static uniaxial compression tests at room temperature and the Split Hopkinson Pressure Bar(SHPB)tests under room temperature and high temperature were conducted.The curves of true stress-true strain were gained and analyzed.The modified constitutive model was established.The finite element simulations on surface grinding by single abrasive grain using ABAQUS software were carried out in the second.Experiments of creep feed grinding narrow deep grooves of 06Cr18Ni11 Ti were performed using a single layer electroplated cubic boron nitride(CBN)wheel at last.The project was supported by the National Natural Science Foundation of China(51575375).The main contents of this paper were as follows:(1)The present situation of stainless steel and its processing technology was studied.The machining technology of narrow and deep groove was analyzed,and the creep feed grinding technology and its application in machining narrow deep grooves were discussed in detail.(2)The dynamic mechanical properties and the constitutive model of 06Cr18Ni11 Ti were studied.The quasi-static uniaxial compression tests at room temperature were carried out at first,and the Split Hopkinson Pressure Bar(SHPB)tests were carried out in the second.The curves of true stress-true strain were gained and analyzed.The fitting of the constitutive equation of the material was carried out.The modified Johnson-Cook constitutive model was established according to the experimental data.The flow stresses at a range of temperature from 20 oC to 300 oC and strain rates from 0.0056s-1 to 2500s-1 were predicted by the modified constitutive model.The predicted data and experimental data were in good agreement with the data for R2=0.97042.The average errors between the predicted data and experimental data under studied experimental conditions was 2.629%?(3)The finite element simulation on surface grinding by single abrasive grain was carried out.Using ABAQUS software,the simulation model of single cubic boron nitride(CBN)abrasive grain grinding 06Cr18Ni11 Ti workpiece was established.The simulations of grinding process with different grinding wheel speed,different thickness of the undeformed chip,different rake angle were carried out.The influences of grinding parameters on the grinding force,the equivalent stress and the temperature of the grinding zone were studied.(4)Experiments were carried out machining 06Cr18Ni11 Ti workpiece using a single layer electroplated CBN wheel,a WinTec MV-40 machining center and creep feed grinding following orthogonal test method were used.The surface quality of the narrow deep grooves was analyzed by the method of range analysis and surface topography.The influence of grinding parameters(including wheel speed,feed rate and cutting depth)on the surface roughness of the grooves was studied.The optimum parameters of grinding the 06Cr18Ni11 Ti narrow deep groove were achieved in view of using the MV-40 machining center.A model predicting the surface roughness Ra values of the machined grooves was established by processing the collected data by Partial Least Square Regression.The regression function fits well with the data for R2=0.947833,and the model is significant on the whole with the data for P-Value=0.038574 at 95% confidence level.