Extrapolation of Creep Curve and Creep Life Prediction From Secondary Creep by Evaluation of Strain Rate Change

2010 ◽  
Author(s):  
Hiroyuki Sato
Keyword(s):  
Strain Rate ◽  
Creep Curve ◽  
Life Prediction ◽  
Temperature Reconstruction ◽  
Rate Change ◽  
Secondary Creep ◽  
Creep Life ◽  
Strain Rate Change ◽  
Creep Life Prediction ◽  
Creep Curves

New method of creep life prediction by Strain-Acceleration-Parameter, SAP, is presented. Sato has found that shapes of creep curves can be characterized by the SAP that reflects magnitude of strain-rate change in secondary creep [1–4]. The SAP values are defined at minimum creep rates, and show the shapes of a creep curve, that depends on stress and temperature. Reconstruction of creep curves by a combination of SAP and a minimum-creep rate is successfully performed, and the extrapolated curves agree well with experiment. The predicted life times also reasonably agree with that obtained by experiment. The possibility of precise life prediction by SAP is pronounced. One of an important advantage of the proposed method is that the required parameters evaluated by individual creep curve are simpler than that are used in methods previously proposed, i.e., the theta projection concept, for example. Possibilities of wide application on many kinds of heat resistant materials should be investigated with the method of SAP.

Extrapolation of Sigmoidal Creep Curve by Strain Acceleration Parameter

2013 ◽  
Vol 592-593 ◽  
pp. 606-609 ◽  
Author(s):  
Hiroyuki Sato ◽  
Kosuke Omote ◽  
Akira Sato ◽  
Kouki Ueno
Keyword(s):  
Strain Rate ◽  
High Temperatures ◽  
Creep Curve ◽  
Primary Creep ◽  
Microstructural Change ◽  
Rate Change ◽  
Strain Rate Change ◽  
Acceleration Parameter ◽  
Creep Characteristics ◽  
Creep Curves

It has been widely accepted that the creep characteristics at high temperatures are mainly evaluated by a minimum creep rate and a time to fracture. Although, a shape of creep curve may vary depending on deformation conditions, the apparent minimum creep rates may become the same value. Thus, for detailed analysis and prediction of creep behavior, other values should be considered which reflects the shape of each creep curve. For the purpose, authors have proposed Satos Strain-Acceleration-Parameter (SAP) which reflects strain rate change during creep. Based on the concept of SAP, the whole creep curve can be represented by a set of small numbers of numerical parameters, and can be extrapolated from a part of creep curve [. It is also well accepted that the creep rates depend on microstructures, and microstructural changes cause strain rate change. The SAP would reflect stability and magnitude of microstructural change during deformation at high temperatures. In this paper, application of the concept of SAP to creep curves that show sigmoidal type primary creep is presented. The creep curve can be divided into two regime based on the SAP values. The sigmoidal creep curve is reasonably reproduced by the concept of Strain-Acceleration-Parameter, and reasonably agrees with experiment. Whole creep curve can be reasonably represented by a few numerical values which reflect shape of creep curve in each regime. The concept of SAP is applicable for quantitative evaluation of both normal and sigmoidal type of creep curves.

A modified θ projection model for constant load creep curves-II. Application of creep life prediction

2019 ◽  
Vol 35 (4) ◽  
pp. 687-694 ◽  
Author(s):  
Chao Fu ◽  
Yadong Chen ◽  
Xiaofei Yuan ◽  
Sammy Tin ◽  
Stoichko Antonov ◽  
...  
Keyword(s):  
Life Prediction ◽  
Constant Load ◽  
Creep Life ◽  
Projection Model ◽  
Creep Life Prediction ◽  
Creep Curves

Creep Life Prediction of T91/12Cr1MoV Dissimilar Welded Joint

2013 ◽  
Vol 330 ◽  
pp. 304-309
Author(s):  
Hu Chen ◽  
Jin Dan Zhu
Keyword(s):  
Experimental Data ◽  
Creep Test ◽  
Life Prediction ◽  
Welded Joint ◽  
Test Results ◽  
Creep Life ◽  
Dissimilar Welded Joint ◽  
Creep Life Prediction ◽  
Creep Curves ◽  
Good Agreement

Based on the creep test results of T91/12Cr1MoV dissimilar welded joint at different conditions, the creep curves of this dissimilar welded joint were established by modified θ projection concept. Low stress creep life was predicted by this curve and the established creep curve shows a good agreement with the experimental data. For computation, Larson-Miller parameters method was also used in creep life forecasting of T91/12Cr1MoV dissimilar welded joint. The resu lt showed that the modified θ projection concept was more accurately in predicting the creep life than Larson-Miller parameters method in allusion to T91/12Cr1MoV dissimilar welded joint.

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.

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