Creep Test And Failure Study Of Full Size P92 Steel Pipe Elbow

Since the beginning of this century with the construction of a large number of supercritical units,especially the construction and operation of ultra supercritical units in recent years,coupled with the "big pressure on the small" guide,a lot of boiler in power plant operation temperature and pressure rise overall which has become the main direction of the new million units,the operating temperature and the high temperature heating component main parameter has also been to improve.When the operating temperature of the component is above 630?,the oxidation resistance and creep properties of P92 steel will decrease with the increase of temperature.This is a new requirement for the basic life and safety of the material,in which the boiler elbow part is the most vulnerable part.Due to the change of wall thickness and ellipticity and the complex stress changes between the inner and outer walls of elbow,many factors have led to the elbow part becoming an important part affecting the safe operation of boiler.In actual operation,the inducement of flow change and abnormal operation will make the elbow become one of the most seriously affected parts.Therefore,by designing elbow test and scientific research,we can achieve reasonable and effective implementation plan for pipeline design and management evaluation,and also provide material test data support for developing higher parameter units.Based on the collection of a large number of the known research results,according to the technical features of design and improve the applied transverse thrust condition creep test of P92 steel pipe elbow,the creep test of high temperature pipe elbow for 1000h at 650 C was completed and an interruption was taken at 500h.At the same time,8 observation points are selected in the middle section,and 3 of them are designed to collect the strain of different measuring points.,the study of complex stress condition of P92 steel wall thickness variation and the variation of hardness and stress distribution changes with time and the influence on the creep behavior.In addition to select the appropriate model based on the finite element analysis of the structure and in the late binding temperature coupling was analyzed by using the uniaxial data fitting parameters,developed using ANSYS simulation through the UPFs interface,creep simulation analysis of the third stages of creep damage accelerating creep stage,to make up for the test time is short faults,creep research the elbow of the relationship,the time-varying stress distribution,damage trends and other issues,the results show that the stress distribution of different time and position of the injury is different,and will affect the distribution of elbow creep.The actual situation,elbow in the bending process of the wall thickness will change significantly,it is because of this change will lead to the elbow stress state change,through the simulation analysis and Research on non uniform wall thickness and other factors on the elbow stress distribution and the influence of creep and damage on the development of the situation changes.By comparing the bending creep test strain results collected with ANSYS simulated strain results,further analysis of the difference of uniaxial compression test of the classic application of constitutive model to creep under multiaxial stress state is produced with the actual situation,discuss the verification of the creep constitutive model is applied to the complex stress condition and feasibility the reliability,thus providing a theoretical basis for the high temperature metal model and multi axial creep simulation.