Comparative Study of Creep Behavior in 9Cr-1Mo Steel With Different Prediction Methods

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Lin Zhu ◽  
Xinbao Liu ◽  
Ping Fan ◽  
Jianqiu Liu ◽  
Chengfei Pan
Keyword(s):  
Creep Rate ◽  
Minimum Creep Rate ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Model Combination ◽  
Creep Life ◽  
Physically Based ◽  
Term Creep ◽  
Short Term Creep

Abstract Over the range of variables (temperature and stress) normally encountered in service applications, creep behaviors of 9Cr-1Mo steel were investigated with various models, such as Wilshire model, combination of exponential form and omega (CEO) model, and continuum damage mechanics (CDM) model. First, a series of short-term creep data was prepared to evaluate the material parameters occurring in these models. Then, creep curve, minimum creep rate, and long-term creep life of present 9Cr-1Mo steel were extrapolated with these estimated models. Based on the analysis of obtained results in detail, it suggested that both CDM model and CEO model can give reliable minimum creep rate predictions. However, the most reliable values of long-term creep life are obtained by the CDM model, followed by the Wilshire model and then the CEO model. In particular, the physically based CDM model can provide useful insights into the underlying creep mechanisms. Therefore, the CDM model has promising potential to study the long-term creep behaviors of 9Cr-1Mo steels.

Long-Term Creep Life Estimation for Manaurite XM Material, Using a Constrained Monkman-Grant Plot and Proportional Similitude

2011 ◽  
Author(s):  
Howard R. Voorhees ◽  
H. Chong Rhee ◽  
Michael K. Baker
Keyword(s):  
Creep Rate ◽  
Early Stage ◽  
Test Results ◽  
Steady Creep ◽  
Creep Life ◽  
General Validity ◽  
Curve Fit ◽  
Term Creep ◽  
Short Term Creep

The present paper revisits a constrained use of Monkman-Grant coordinates, a relatively little employed or appreciated method for estimation of long-term creep life. This method is based on a logarithmic plot of remaining life versus the steady creep rate. A procedure, here called proportional similitude, is also discussed as a means to estimate the steady creep rate or time to rupture at an early stage of a test. Numerous studies as yet mostly unpublished increasingly demonstrate for many steel samples from prior creep service that a combination of these two methods permits extrapolations at least as soon, as accurate, and at overall cost similar to other popular procedures. One of the advantages of this procedure is that short term creep test results can be extrapolated to long-term creep life in a transparent manner without complex mathematical maneuvers or need for typical reference properties or initial behavior of the sample. Results now available for a variety of widely-employed materials suggest that these methods may have more-general validity for remaining creep life evaluations than industry has recognized. This paper presents remaining creep lives obtained though a combination of four procedures, i.e., Monkman-Grant, proportional similitude, Larson-Miller, and curve fit methods, for exposed hydrogen reformer tube samples. Results are compared with those of previous Omega analyses performed independently for the same sample.

Short-Term Creep Data Based Long-Term Creep Life Predictability for Grade 92 Steels and Its Microstructural Basis

2018 ◽  
Vol 25 (3) ◽  
pp. 713-722 ◽  
Author(s):  
Seen Chan Kim ◽  
Jae-Hyeok Shim ◽  
Woo-Sang Jung ◽  
Yoon Suk Choi
Keyword(s):  
Creep Data ◽  
Creep Life ◽  
Short Term ◽  
Term Creep ◽  
Short Term Creep

Creep Life Prediction of Gr.91 Using Creep Parameters in Transient Region

2012 ◽  
Author(s):  
Fujio Abe
Keyword(s):  
Creep Rate ◽  
Minimum Creep Rate ◽  
Life Prediction ◽  
Test Duration ◽  
Creep Life ◽  
Average Value ◽  
Transient Region ◽  
Creep Life Prediction ◽  
Wide Range ◽  
Term Creep

The creep deformation behavior and its effect on creep life have been investigated for Gr.91 by analyzing creep strain data in the NIMS Creep Data Sheet. The creep life tr is mainly determined by the minimum creep rate ε̇min, indicating tr ∝ (ε̇min)−1. The ε̇min is mainly determined by the time to minimum creep rate tm, indicating ε̇min ∝ (tm)−1. Then the creep life is correlated with the tm as tr=3.7tm, where the constant 3.7 is as an average value for a wide range of temperature (450–725 °C), stress (40–450 MPa) and test duration (11–68,755 h). Using this equation, we can predict the creep life by carrying out a short-term creep test for up to the end of transient region, corresponding to about 30% of creep life. The (tm/tr), the ratio of duration of transient region to the creep life, slightly decreases with decreasing stress and is evaluated to be 0.22 at 100 MPa and above 550 °C, which gives us tr= 4.5 tm at 100 MPa. Taking the stress dependence of the (tm/tr) into account, the accuracy of creep life prediction is further improved.

Unified Viscoplastic Model Coupled With Damage for Evaluation of Creep-Fatigue of Grade 91 Steel

2017 ◽  
Author(s):  
Nazrul Islam ◽  
David J. Dewees ◽  
Tasnim Hassan
Keyword(s):  
Damage Mechanics ◽  
Creep Damage ◽  
Continuum Damage Mechanics ◽  
Creep Model ◽  
Damage Evaluation ◽  
Creep Fatigue ◽  
Grade 91 ◽  
Term Creep ◽  
Grade 91 Steel

A continuum damage mechanics (CDM) coupled unified viscoplasticity model has been developed to predict the creep-fatigue life of modified Grade 91 steel. A tertiary creep model termed MPC-Omega codified in Part 10 of API (and also implemented in the ASME BP&V Code for Grade 22V and more recently Grade 91 Steel) is also employed for creep damage evaluation. As MPC-Omega has a direct relationship with Larson-Miller parameter (LMP) coefficients, creep damage coefficients in the unified constitutive model (UCM) are tied with MPC-Omega coefficients in order to utilize WRC and API 579-1 Grade 91 creep rupture database. The model is validated against long-term creep, LCF, creep-fatigue and TMF experimental responses at T = 20–600°C.

Creep Life Prediction of Aircraft Turbine Disc Alloy Using Continuum Damage Mechanics

2017 ◽  
Vol 38 (1) ◽  
pp. 25-30
Author(s):  
Yan-Feng Li ◽  
Zhisheng Zhang ◽  
Chenglin Zhang ◽  
Jie Zhou ◽  
Hong-Zhong Huang
Keyword(s):  
Numerical Analysis ◽  
Test Data ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Creep Model ◽  
Continuum Damage ◽  
Creep Life ◽  
Creep Life Prediction ◽  
Turbine Disc

Abstract This paper deals with the creep characteristics of the aircraft turbine disc material of nickel-base superalloy GH4169 under high temperature. From the perspective of continuum damage mechanics, a new creep life prediction model is proposed to predict the creep life of metallic materials under both uniaxial and multiaxial stress states. The creep test data of GH4169 under different loading conditions are used to demonstrate the proposed model. Moreover, from the perspective of numerical simulation, the test data with analysis results obtained by using the finite element analysis based on Graham creep model is carried out for comparison. The results show that numerical analysis results are in good agreement with experimental data. By incorporating the numerical analysis and continuum damage mechanics, it provides an effective way to accurately describe the creep damage process of GH4169.

scholarly journals Effect of Low-Temperature Annealing on Creep Properties of AlSi10Mg Alloy Produced by Additive Manufacturing: Experiments and Modeling

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 179
Author(s):  
Chiara Paoletti ◽  
Emanuela Cerri ◽  
Emanuele Ghio ◽  
Eleonora Santecchia ◽  
Marcello Cabibbo ◽  
...  
Keyword(s):  
Creep Rate ◽  
Applied Stress ◽  
Minimum Creep Rate ◽  
Annealing Treatment ◽  
Constant Load ◽  
Experimental Conditions ◽  
Creep Properties ◽  
Low Temperature Annealing ◽  
Physically Based ◽  
Excellent Description

The effects of postprocessing annealing at 225 °C for 2 h on the creep properties of AlSi10Mg alloy were investigated through constant load experiments carried out at 150 °C, 175 °C and 225 °C. In the range of the experimental conditions here considered, the annealing treatment resulted in an increase in minimum creep rate for a given stress. The reduction in creep strength was higher at the lowest temperature, while the effect progressively vanished as temperature increased and/or applied stress decreased. The minimum creep rate dependence on applied stress was modeled using a physically-based model which took into account the ripening of Si particles at high temperature and which had been previously applied to the as-deposited alloy. The model was successfully validated, since it gave an excellent description of the experimental data.

Prediction of Long Term Stress Rupture Data for 2124

2006 ◽  
Vol 519-521 ◽  
pp. 1041-1046 ◽  
Author(s):  
Brian Wilshire ◽  
H. Burt ◽  
N.P. Lavery
Keyword(s):  
Q Methodology ◽  
Fracture Behavior ◽  
Stress Rupture ◽  
Creep Data ◽  
Short Term ◽  
Rupture Data ◽  
Term Creep ◽  
Term Data ◽  
Short Term Creep

The standard power law approaches widely used to describe creep and creep fracture behavior have not led to theories capable of predicting long-term data. Similarly, traditional parametric methods for property rationalization also have limited predictive capabilities. In contrast, quantifying the shapes of short-term creep curves using the q methodology introduces several physically-meaningful procedures for creep data rationalization and prediction, which allow straightforward estimation of the 100,000 hour stress rupture values for the aluminum alloy, 2124.

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