Long-term creep strength predictions from short-term creep test data for high Cr creep-resistant steels and microstructural evolution origin of over-predictions

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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EXTRAPOLATION OF SHORT TERM CREEP DATA INTO LONG TERM RUPTURE TIME PREDICTIONS VIA CAVITY NUCLEATION MEASUREMENTS

Materials at High Temperatures ◽

10.1080/09603409.2021.1979744 ◽

2021 ◽

pp. 1-7

Author(s):

Kostas Davanas

Keyword(s):

Rupture Time ◽

Creep Data ◽

Short Term ◽

Cavity Nucleation ◽

Term Creep ◽

Short Term Creep

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Microstructural evolution of delta ferrite in SAVE12 steel under heat treatment and short-term creep

Materials Characterization ◽

10.1016/j.matchar.2012.08.009 ◽

2012 ◽

Vol 73 ◽

pp. 144-152 ◽

Cited By ~ 25

Author(s):

Shengzhi Li ◽

Zumrat Eliniyaz ◽

Lanting Zhang ◽

Feng Sun ◽

Yinzhong Shen ◽

...

Keyword(s):

Heat Treatment ◽

Microstructural Evolution ◽

Short Term ◽

Delta Ferrite ◽

Term Creep ◽

Short Term Creep

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

Metals and Materials International ◽

10.1007/s12540-018-00214-x ◽

2018 ◽

Vol 25 (3) ◽

pp. 713-722 ◽

Cited By ~ 1

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

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New Numerical Analysis Method for Creep Lifetime of Gas Turbine Materials by Using the Discrete Cosine Transform

Volume 10B: Structures and Dynamics ◽

10.1115/gt2020-14029 ◽

2020 ◽

Author(s):

Hideo Hiraguchi

Keyword(s):

Discrete Cosine Transform ◽

Creep Curve ◽

Creep Data ◽

Short Term ◽

Cosine Transform ◽

Discrete Signals ◽

Creep Region ◽

Term Creep ◽

Short Term Creep

Abstract Recently the Discrete Cosine Transform[1], [2], [3] which is a modified Fourier Transform has begun to be used to express coefficients of creep equations using the power law or the exponential law such as Bailey-Norton law[4], [5] and θ Projection[6], [7], [8], [9], [10]. In addition, the Discrete Cosine Transform has begun to be used to express a creep equation itself. We have already found that the Discrete Cosine Transform can express the temperature and stress dependence property of the coefficients of the creep equations at the same time by the two-dimensional Discrete Cosine Transform using 8 × 8 discrete signals[11]. Furthermore, we have already found that the Discrete Cosine Transform can fit measured creep strain values very well from the primary creep region to the tertiary creep region using 8 discrete signals and it can estimate creep strain values between the measured points by interpolation very well[12]. However it has not been known if the Discrete Cosine Transform can predict the long term creep curve by using the short term creep data yet. Therefore, as a next stage, we tried to estimate the long term creep curve from the short term creep data of gas turbine materials by extrapolation using the Discrete Cosine Transform. As a result, we were able to obtain a useful numerical analysis method by utilizing the Discrete Cosine Transform Coefficients and others as a new extrapolation method. It is found that this new numerical method would be able to predict the configuration of 150,000-hour creep curve by using 500-hour to 13,000-hour short term creep data.

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Quantitative Evaluation of Secondary Phases in a Weld Joint Made of COST F and FB2 Creep Resistant Steels

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.270.183 ◽

2017 ◽

Vol 270 ◽

pp. 183-188

Author(s):

Dagmar Jandová

Keyword(s):

Quantitative Evaluation ◽

Creep Strength ◽

Weld Joint ◽

Precipitate Size ◽

Secondary Phases ◽

Creep Tests ◽

Transmission Electron ◽

Creep Resistant Steels ◽

Term Creep

Conventional (CCT) and accelerated (ACT) creep tests of a weld joint made of COST F and COST FB2 steels were carried out over a temperature range from 550 °C to 650 °C. Fracturing of the crept specimens was located in the heat affected zone (HAZ) of the F steel. Two specimens were selected after CCT and ACT for quantitative evaluation of the precipitates and compared to the weld joint in as-received conditions. Scanning and transmission electron micrographs were used to measure the precipitate size. Both methods were compared and the accuracy of the results was discussed. It was concluded that ACT can simulate the precipitation of chromium carbides and structure recovery during long term creep exposures. However, precipitation of Laves phase during CCT was not recorded after ACT. Therefore, it is difficult to use ACT in this experiment for estimating the long term creep strength.

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