Investigating creep rupture and damage behaviour in notched P92 steel specimen using a microscale modelling approach

Zhao, Lei; Alang, N. A.; Nikbin, Kamran

doi:10.1111/ffe.12713

Cited by 21 publications

(14 citation statements)

References 52 publications

(138 reference statements)

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“…In structural metals deformed at room temperature, the voids generally nucleate by decohesion of second phase particles or by particle fracture, and grow by plastic deformation of the surrounding matrix. Void coalescence occurs either by necking down of the matrix material between adjacent voids or by localized shearing between well separated voids, as has been described in a previous review paper [38,39]. Furthermore, for materials deformed at elevated temperature, grain-boundary slide, wedge-cracks, or voids grow on boundaries lying roughly normal to the tensile axis are usually considered as the crack recourses, which is known as an creep-controlled intergranular fracture [40].…”

Section: Fractography Analysismentioning

confidence: 99%

Creep Behavior and Life Assessment of a Novel Heat-Resistant Austenite Steel and Its Weldment

Jing

Han

et al. 2018

Acta Metall. Sin. (Engl. Lett.)

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In the present study, creep activation energy for rupture was obtained as 221-348 kJ/mol for 22Cr15Ni3.5CuNbN due to the precipitation-hardening mechanism. The extrapolation strength of creep rupture time of 10 5 h at 923 K for 22Cr15Ni3.5CuNbN is more valid (83.71 MPa) predicted by the Manson-Haferd method, which is superior to other commercial heat-resistant steels. The tensile creep tests ranging from 180 to 240 MPa at 923 K were conducted to investigate creep deformation behavior of welded joint between a novel heat-resistant austenite steel 22Cr15Ni3.5CuNbN and ERNiCrCoMo-1 weld metal. Apparent stress exponent value of 6.54 was obtained, which indicated that the ratecontrolled creep occurred in weldment during creep. A damage tolerance factor of 6.4 in the weldment illustrates that the microstructural degradation is the dominant creep damaging mechanism in the alloy. Meanwhile, the welded joints perform two types of deformation behavior with the variation in applied stress, which resulted from the different parts that govern the creep processing. Also, the morphology evolution of the fracture surfaces confirms the effects of stress level and stress state. Keywords Heat-resistant steel weldment Á Creep deformation Á Life assessment Á TTP (time-temperature parametric) method Recent researches on life assessment of high-temperature alloys used in power plants, nevertheless, mainly converge on grades 91 and 92 [9-13]. The long-term lifetime extrapolation and allowable stress calculation are particularly inadequate for newly developed high-temperature steel. Meanwhile, welding is an inevitable processing

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Section: Fractography Analysismentioning

confidence: 99%

Creep Behavior and Life Assessment of a Novel Heat-Resistant Austenite Steel and Its Weldment

Jing

Han

et al. 2018

Acta Metall. Sin. (Engl. Lett.)

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“…This requires the use of advanced oxidation and creep‐resistant materials with superior performances. The temperature of the next generation ultra‐supercritical (USC) power plants will be improved to over 600°C, even up to 700°C for advanced USC power plants 1–4 . Up to now, the suitable and mature materials and the matched welding materials for advanced USC power plants have not been developed.…”

Section: Introductionmentioning

confidence: 99%

Analysis on stress‐strain behavior and life prediction of P92 steel under creep‐fatigue interaction conditions

Zhao

Han

et al. 2020

Fatigue Fract Eng Mat Struct

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Considering the flexible operation conditions, the creep‐fatigue performance of P92 steel plays a crucial role in manufacturing structural components of ultra‐supercritical fossil power plants at 620°C–630°C. The creep‐fatigue interaction tests of P92 steel were conducted at 630°C in air with different duration periods, where the duration periods were simultaneously added on the peak tensile strain and valley compressive strain. The addition of hold time resulted in a rapid decrease of fatigue life, where the reduction amplitude increasing with the hold time. There was more than five times reduction as the hold time increased to 300 s. Moreover, the stress relaxation behavior during hold time exhibited a saturation behavior at long dwell time, where the limited relaxed stress gradually approached to the creep threshold stress. Furthermore, a modified strain energy density exhaustion model involving creep threshold stress was proposed and provided more accurate predictions in comparison with the conventional model, reducing the conservatism.

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“…The maximum value of triaxiality was found to be at the notch centre and the lower value at the notch root for all applied stresses for lower acuity. It is also well established that [7], high triaxiality causes brittle fracture while low triaxiality is responsible for ductile fracture. As a result, brittle-like fractures are frequently detected on higher-acuity creep samples.…”

Section: Resultsmentioning

confidence: 99%

“…This behaviour, however, tends to saturate to a sharp notch. In another study on P91 steel, Zhao et al [7] reported that the damage initiation position is influenced by the notch radius and external stress. For sharp notch, the damage or crack propagated both towards the notch root and the centre of specimens.…”

Section: Introductionmentioning

confidence: 98%

Numerical Prediction of Creep Rupture Life of Ex-Service and As-Received Grade 91 Steel at 873 K

Ferdous

Alang

Alias

et al. 2021

IJAME

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Infallible creep rupture life prediction of high temperature steel needs long hours of robust testing over a domain of stress and temperature. A substantial amount of effort has been made to develop alternative methods to reduce the time and cost of testing. This study presents a finite element analysis coupled with a ductility based damage model to predict creep rupture time under the influence of multiaxial stress state of ex-service and as-received Grade 91 steel at 873 K. Three notched bar samples with different acuity ratios of 2.28, 3.0 and 4.56 are modelled in commercial Finite Element (FE) software, ABAQUS v6.14 in order to induce different stress state levels at notch throat area and investigate its effect on rupture time. The strain-based ductility exhaustion damage approach is employed to quantify the damage state. The multiaxial ductility of the material that is required to determine the damage state is estimated using triaxiality-ductility Cock and Ashby relation. Further reduction of the ductility due to the different creep mechanisms over a short and long time is also accounted for in the prediction. To simulate the different material conditions: ex-service and as-received material, different creep coefficients (A) have been assigned in the numerical modelling. In the case of ex-service material, using mean best fit data of minimum creep strain rate gives a good life prediction, while for new material, the lower bound creep coefficient should be employed to yield a comparable result with experimental data. It is also notable that ex-service material deforms faster than as-received material at the same stress level. Moreover, higher acuity provokes damage to concentrate on the small area around the notch, which initiates higher rupture life expectancy. It also found out that, the stress triaxiality and the equivalent creep strain influence the location of damage initiation around the notch area.

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Investigating creep rupture and damage behaviour in notched P92 steel specimen using a microscale modelling approach

Cited by 21 publications

References 52 publications

Creep Behavior and Life Assessment of a Novel Heat-Resistant Austenite Steel and Its Weldment

Creep Behavior and Life Assessment of a Novel Heat-Resistant Austenite Steel and Its Weldment

Analysis on stress‐strain behavior and life prediction of P92 steel under creep‐fatigue interaction conditions

Numerical Prediction of Creep Rupture Life of Ex-Service and As-Received Grade 91 Steel at 873 K

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