Study On Deformation Control Of Large Cylinder Section During Heat Treatment

Large barrel joint is the core basic component in petrochemical,nuclear and other fields,and plays a decisive role in the stable operation of large equipment.Large cylinder sections are used in harsh environments such as high temperature and high pressure,so they need to have excellent mechanical properties.In actual production,the comprehensive mechanical properties of large cylinder joints are improved by quenching and tempering heat treatment.However,large cylinder joints usually deform after quenching and tempering heat treatment,resulting in unqualified product quality and high cost.Therefore,this paper focuses on the research on the influence of heat treatment process parameters on the deformation of large cylinder sections,and carries out physical tests and numerical simulation to provide reference for optimizing the actual process.In this paper,the thermophysical parameters and the true stress-strain curve of2.25Cr-1Mo-0.25 V steel are obtained by using the test method,and the TTT curve is obtained by using JMat Pro software,and a complete database of 2.25Cr-1Mo-0.25 V steel heat treatment performance is established.The prediction model of the microstructure field of 2.25Cr-1Mo-0.25 V steel during heat treatment is established by using the USDFLD and HETVAL subroutines in the finite element software ABAQUS.The influence of phase change latent heat on temperature is considered in the heat treatment process,and the influence of phase change latent heat on temperature is considered in the numerical simulation process.In this paper,316 LN austenitic stainless steel and 2.25Cr-1Mo-0.25 V steel are used for quenching test,and the quenching process temperature is measured,and the quenching process temperature change curve is obtained.The temperature change curve of 316 LN austenitic stainless steel and DEFORM software were used to calculate the change of heat transfer coefficient with temperature during quenching.Based on the established numerical simulation model,the quenching process of 316 LN austenitic stainless steel and2.25Cr-1Mo-0.25 V steel was numerically simulated,and the numerical simulation results were compared with the test results.The results show that the numerical simulation results are in good agreement with the experimental results,which verifies the accuracy of the numerical simulation model.Use FLUENT software to determine the heat transfer coefficient of large cylinder section during quenching.The established numerical simulation model is used to simulate the heat treatment process of large cylinder section.Consider the changes of temperature field,stress field,microstructure field and deformation of large cylinder section under different process conditions.Determine the influence of transfer time and quenching speed on temperature field,stress field,microstructure field and deformation of large cylinder section.The results show that the optimum heat treatment process conditions for large cylinder sections are 7 min transfer time and 180 mm/s quenching speed.