Basic Research On Quenching Stress Calculation Of 12Cr2Ni4A Steel

As an important heat treatment method,quenching can improve the microstructure and performance of parts,and is widely used in aerospace,aviation and transportation manufacturing fields.In the quenching process,the temperature of parts changes dramatically,which will produce uneven temperature distribution and uneven transformation,and easily make the quenching stress too large.Therefore,it is very important to accurately predict the stress change in the quenching process,which is directly related to the deformation and cracking tendency of parts,and is an important basis for the formulation of quenching process.The quenching process simulation software used in China are all products of foreign companies.In this paper,the 12Cr2Ni4 A steel cylinder sample is taken as the research object,and the basic research on the simulation of quenching process is carried out.The main research studies of the paper are as follows:(1)The interaction relationship between the carburizing concentration field,temperature field,microstructure field and stress-strain field is discussed.The influence of deformation heating and stress-induced phase transition is ignored.After simplification,the coupling relationship of multiple fields changes from complete coupling to sequential coupling.Based on thermo-elastic-plastic mechanics,the elastic-plastic incremental constitutive relation was derived,which considered the influence of temperature and phase transformation comprehensively.Combined with diffusion dynamics,heat transfer and phase transformation dynamics,a multi-field coupled mathematical model was established for quenching process.(2)Based on the multi-field coupling mathematical model,the corresponding simulation program is developed through the interface provided by Abaqus.USDFLD,HETVAL and UMAT subroutines were written to realize the quenching calculation function.A carbon potential judgment module is added to the subroutine,and the carburizing and quenching calculation can be performed when there is an external carbon potential input.(3)The thermal physical parameters,phase transformation dynamic parameters and mechanical properties parameters of each sub-phase were calculated by JMat Pro software.The heat treatment process route is determined,and the model displacement constraints and thermal boundary conditions are given.The finite element model of quenching and carburizing quenching of 12Cr2Ni4 A steel cylinder samples is established,and simulation analysis is carried out.(4)The evolution of the temperature,microstructure and stress calculated by independent programming during the quenching process is compared with the calculation results of DANTE.Combined with residual stress experiments,the calculation accuracy of the subroutine is verified.(5)The stress evolution law of 12Cr2Ni4 A cylinder sample during carburizing and quenching was analyzed by using independent programming.In this paper,a multi-field coupling mathematical model suitable for quenching process is established,and the corresponding Abaqus subroutine is developed,which can be used to predict quenching stress of12Cr2Ni4 A steel sample.Based on this research,the evolution law of stress and the distribution law of residual stress during quenching and carburizing quenching of 12Cr2Ni4 A steel samples are obtained,which can guide the formulation of quenching process.