Research On Hot Extrusion Process And Microstructure Evolution Of IN690 Superalloy Tube

IN690 super alloy is widely used in steam engines and pressurized water reactor because of its excellent corrosion cracking resistance,high strength,good stability and excellent processing characteristics,etc.The tubing extrusion process of IN690 super alloy had been studied by using DEFORM-3D software,Cellular Automata(CA)and advanced experimental testing method.The main results and conclusions are as follows:(1)The temperature and stress field of the extrusion die under different parameters had been studied by stress analysis module of the finite element software DEFORM-3D.Reducing the extrusion temperature and the friction coefficient,increasing the extrusion speed,the final temperature of the mold is reduced;Increasing the extrusion temperature and the extrusion speed,reducing the friction coefficient and the extrusion ratio,the maximum principal stress value of the die is reduced;(2)Multi-field coupling of IN690 super alloy tubing extrusion process based on finite element software DEFORM-3D had been simulated.The distribution law of temperature,stress and strain field and extrusion pressure had been studied under different process parameters.The influence rules of different process parameters on the tube extrusion process was obtained;(3)Dynamic recrystallization(DRC)microstructure evolution of IN690 super alloy during tube extrusion process had been studied by numerical simulation.The evolution law of dynamic recrystallization and the average grain size at different extrusion parameters were obtained;Complete dynamic recrystallization region and the average grain size become larger with the increase of extrusion temperature;Increasing the extrusion speed,the complete dynamic recrystallization region becomes larger,and the average grain size decreases;Increasing the extrusion ratio,the complete dynamic recrystallization region becomes larger,and the average grain size decreases;In the direction of pipe wall thickness,the average grain size increases firstly and then decreases.(4)Dynamic recrystallization of IN690 super alloy during tube extrusion had been simulated based on Cellular Automata(CA).It had been determined that model of dislocation density and model of reply and model of nucleation and model of grain growth.It had been obtained that grain morphology and distribution and orientation and size during the process of deformation;(5)The tube extrusion experiment of IN690 super alloy had been completed.The structure property of tube had been analyzed.The simulation results w in agreement with the experimental results.The relative error of the average grain size of the numerical simulation and experiment is less than 15.97% through comparison the numerical simulation and experiment microstructure.