Fatigue Simulation Of Reactor Weld Zone Under High Temperature And High Pressure With Hydrogen Permeation

Hydrogen production reactor runs for a long time under extreme conditions such as high temperature,high pressure and hydrogen presence,and its weld zone is prone to performance degradation,which seriously affects the reliability of reactor operation.In order to ensure the normal operation of hydrogen reactor and prolong its service life,it is necessary to analyze and study the fatigue life of welding seam under the condition of high temperature and high pressure near hydrogen.In this paper,the evolution of weld material properties under thermal-mechanical-chemical coupling was simulated and analyzed,and the influence law of extreme working conditions and groove form on weld fatigue life of reactor was obtained.The main research contents are as follows:(1)The thermal-mechanical-chemical coupling finite element model of hydrogen reactor weld was established.Based on the theory of material phase transformation,the hydrogen content ratio in the weld was determined by using the cloud map of hydrogen concentration field affected by temperature and pressure.According to the content of chemical elements in the weld,the material properties of hydrogenation weld were calculated by Jmat Pro software,and the finite element model of thermal-mechanical-chemical coupling weld was established combining with the actual high temperature and high pressure conditions.The finite element model of hydrogenation weld was verified by tensile test data of hydrogenation weld material,and the validity of thermal-mechanical-chemical coupling simulation model was confirmed.The weld stress field and temperature field under the coupling action of multiple fields in the reactor are obtained by using this model,the highest stress occurs in the t-weld zone and fusion zone where the base metal is connected to the weld,which provides reference conditions for the subsequent study of weld fatigue life analysis.(2)Simulation of weld fatigue life based on extreme conditions of high temperature,high pressure and hydrogen.The thermal-mechanical-chemical coupling finite element models of different groove forms were simulated under different extreme conditions.Define stress field simulation results for the fatigue analysis of symmetrical load spectrum of the role of circulation,according to the different temperature of weld s-n curve fitting for fatigue analysis model of the fatigue material parameters,the Fe-safe software on weld fatigue life calculation,it is concluded that in extreme conditions with different groove weld in the form of the weld crack initiation life of laws,The high temperature condition in the reactor has a great influence on the temperature stress on the weld surface,and increases the influence range of hydrogen penetration.The temperature will accelerate the induction of hydrogen penetration into the weld,resulting in the reduction of the fatigue life of the weld surface.(3)Analyze the influence of different factors on the fatigue life of weld and predict it.Through the establishment of weld fatigue simulation model,obtained the extreme working conditions and the Angle of groove,groove blunt edge length to weld the influence law of fatigue life,and by using SPSS,Minitab software analysis such as pressure,temperature and the blunt edge length has more significant effect on weld fatigue life,the regression equation of the fatigue life of the response surface function,Thus the fatigue life of the weld in the reactor can be predicted.In summary,this paper studies the influence of different working conditions and groove forms on weld fatigue life in hydrogen production reactor,providing reference conditions for the study of the inhibition mechanism of weld performance degradation under long-term extreme service conditions.