12% Cr Ultra-supercritical Rotor Steel Heat Treatment For Basic Research And Process Simulation

The high-pressure rotor is an important part of the ultra-supercritical generating units，and the bad working environment requires it should have excellent high temperature creepproperties, thermal fatigue performance and low cycle fatigue performance, etc.12%Crsteel is a kind of heat resistant steel often used to make the high-pressure rotor, but themechanical performances become worse and it is difficult to control the quality of the parts.because of that the steel alloy composition is high, and the size of the high-pressure is large,lead to produce these problems in the hot-working process such as coarse grain, mix crystaland tissue abnormalities and so on. Therefore, studying the changes of the organizations andperformances of12%Cr ultra supercritical pressure rotor in the process of forging and heattreatment is greatly important to improve the hot working technology and the quality of theforging products.This paper is based on the process of forging and heat treatment, by means ofdetermination the CCT curve of the12%Cr steel, researching austenitic grain growth, hightemperature ferritic exhalation and eliminate rules, testing heat treatment temperature fieldheat transfer coefficient, simulating the process of forging, doing Physical experiment aboutthe process of forging and heat treatment, etc, studied the changes of the organizations andperformances of12%Cr steel in the process of forging and heat treatment, and finallyoptimized the process of forging and heat treatment. The main conclusions are:Use expansion method in Gleeble-1500D thermal simulation test enginery todeterminate the CCT curve of the12%Cr steel, and to get Ac1temperature, Ac3temperatureand Ms point temperature of the steel, to infer the heating and cooling process of forgingand after forging heat treatment. According to the temperature of the CCT curve, todetermine the heat treatment temperature range, and study the growth law of austenitic inthe interval, which provide the reference for the grain changes of the process of forging andheat treatment.According to studying the law of the high temperature ferrite’s precipitation andelimination, the results show that the heating temperature exceeds1160℃will lead to alarge number of the high temperature ferrite precipitation, and verify that the mechanical properties of the steel fall because of the existence of high temperature ferrite; and eliminatethe high temperature ferrite only through large deformation produced by forging, whichmake the mechanical properties of the steel to enhance larger.Use the thermocouple to test the temperatures of the measuring point of the12%Crsteel in air cooling and furnace cooling, and based on to Calculate the heat transfercoefficient under the conditions of air cooling and furnace cooling, proven the accuracy, useto analog the temperature changes of the ultra-supercritical rotors in the process of forgingand heat treatment, to provide the basses for making the process of heating and cooling.Use the software of DEFORM-3D to simulate the process of the whole free forging ofthe12%Cr ultra-supercritical pressure rotor and predict the rage of the grains after forging,prepare small samples used to comply with the range after forging, which for the process offorging and heat treatment in different time, simulate that the changes of the organizationsand performances of ultra-supercritical pressure rotor after the process of forging and heattreatment, and finally optimize the process of forging and heat treatment.