• Title/Summary/Keyword: 크리프 수명

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Creep-Life Prediction and Standard Error Analysis of Type 316LN Stainless Steel (Type 316LN 스테인리스 강의 크리프 수명 예측과 표준오차 분석)

  • Yun S.N.;Kim W.G.;Liu W.S.;Yi W.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1406-1411
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    • 2005
  • The creep rupture data for type 316LN stainless steels were collected through literature survey or experimental data produced in KAERI. Using these data, polynomial equations for predicting creep life were obtained by Larson-Miller (L-M), Orr-Sherby-Dorn (O-S-D) and Manson-Haferd (M-H) etc. time-temperature parametric (TTP) methods. Standard error of estimate (SEE) values for the each parameter was obtained with different temperatures through the statistical process of the creep data. The results of L-M, O-S-D and M-H methods showed good creep-life prediction, but M-H method showed better agreement than L-M and O-S-D methods. Especially, it was found that SEE values of M-H method at $700^{\circ}C$ were lower than that of L-M and O-S-D methods.

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New Considerations on Variability of Creep Rupture Data and Life Prediction (크리프 파단 데이터의 변동성에 대한 새로운 고찰과 수명예측)

  • Jung, Won-Taek;Kong, Yu-Sik;Kim, Seon-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.10
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    • pp.1119-1124
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    • 2009
  • This paper deals with the variability analysis of short term creep rupture test data based on the previous creep rupture tests and the possibility of the creep life prediction. From creep tests performed by constant uniaxial stresses at 600, 650 and $700^{\circ}C$ elevated temperature, in order to investigate the variability of short-term creep rupture data, the creep curves were analyzed for normalized creep strain divided by initial strain. There are some variability in the creep rupture data. And, the difference between general creep curves and normalized creep curves were obtained. The effects of the creep rupture time (RT) and steady state creep rate (SSCR) on the Weibull distribution parameters were investigated. There were good relation between normal Weibull parameters and normalized Weibull parameters. Finally, the predicted creep life were compared with the Monkman-Grant model.

Improvement of Long-term Creep Life Prediction Method of Gr. 91 steel for VHTR Pressure Vessel (초고온가스로 압력용기용 Gr. 91 강의 장시간 크리프 수명 예측 방법 개선)

  • Park, Jae-Young;Kim, Woo-Gon;EKAPUTRA, I.M.W.;Kim, Seon-Jin;Kim, Min-Hwan
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.10 no.1
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    • pp.64-69
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    • 2014
  • Gr. 91 steel is used for the major structural components of Generation-IV reactor systems, such as a very high temperature reactor(VHTR) and sodium-cooled fast reactor(SFR). Since these structures are designed for up to 60 years at elevated temperatures, the prediction of long-term creep life is important for a design application of Gr. 91 steel. In this study, a number of creep rupture data were collected through world-wide literature surveys, and using these data, the long-term creep life was predicted in terms of three methods: the single-C method in Larson-Miller(L-M) parameter, multi-C constant method in the L-M parameter, and a modified method("sinh" equation) in the L-M parameter. The results of the creep-life prediction were compared using the standard deviation of error value, respectively. Modified method proposed by the "sinh" equation revealed better agreement in creep life prediction than the single-C L-M method.

Variability of Short Term Creep Rupture Time and Life Prediction in Stainless Steels (스테인리스 강의 단시간 크리프 파단시간의 변동성과 수명예측)

  • Jung, Won-Taek;Kong, Yu-Sik;Kim, Seon-Jin
    • Journal of Ocean Engineering and Technology
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    • v.24 no.6
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    • pp.97-102
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    • 2010
  • This paper deals with the variability of short term creep rupture time based on previous creep rupture tests and the statistical methodology of the creep life prediction. The results of creep tests performed using constant uniaxial stresses at 600, 650, and $700^{\circ}C$ elevated temperatures were used for a statistical analysis of the inter-specimen variability of the short term creep rupture time. Even under carefully controlled identical testing conditions, the observed short-term creep rupture time showed obvious inter-specimen variability. The statistical aspect of the short term creep rupture time was analyzed using a Weibull statistical analysis. The effect of creep stress on the variability of the creep rupture time was decreased with an increase in the stress level. The effect of the temperature on the variability also decreased with increasing temperature. A long term creep life prediction method that considers this statistical variability is presented. The presented method is in good agreement with the Lason-Miller Parameter (LMP) life prediction method.

Creep-Life Prediction and Standard Error Analysis of Type 316LN Stainless Steel by Time-Temperature Parametric Methods (시간-온도 파라미터 방법에 의한 Type 316LN 강의 크리프 수명 예측과 표준오차 분석)

  • Yoon Song Nam;Ryu Woo Seog;Yi Won;Kim Woo Gon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.1 s.232
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    • pp.74-80
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    • 2005
  • A number of creep rupture data for type 316LN stainless steels were collected through literature survey or experimental data produced in KAERI. Using these data, polynomial equations for predicting creep life were obtained by Larson-Miller (L-M), Orr-Sherby-Dorn (O-S-D) and Manson-Haferd (M-H) parameters using time-temperature parametric (TTP) methods. Standard error of estimate (SEE) values for the each parameter was obtained with different temperatures through the statistical process of the creep data. The results of L-M, O-S-D and M-H methods showed good creep-life prediction, but M-H method showed better agreement than L-M and O-S-D methods. Especially, it was found that SEE values of M-H method at $700^{\circ}C$ were lower than that of L-M and O-S-D methods.

입계부식법에 의한 고온플랜트 요소의 크리프 잔여수명 평가

  • 윤기봉;한상인;강태연;박종진
    • Proceedings of the Korean Institute of Industrial Safety Conference
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    • 1998.05a
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    • pp.71-76
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    • 1998
  • 고온플랜트 설비 고온요소의 재질열화 정도를 평가하기 위해서 사용되는 방법 중 입계부식법은 시험절차가 간단하고 실제 플랜트에서의 적용이 용이하여 안전 및 수명진단시에 많이 이용되어 왔다. 본 논문에서는 오랜 기간 고온에서 사용된 고온$\cdot$고압플랜트의 실기 요소에 입계부식법을 적용하여 재질의 고온에서의 장시간 노출에 의한 인성저하로 발생되는 잔여 수명을 평가한 결과를 제시하였다. (중략)

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Prediction of Steady-State Stresses within Heat Affected Zone Due to Creep Mismatch in Welded Straight Pipes (직관 용접부의 크리프 특성 불균일에 따른 열영향부 정상상태 응력 예측)

  • Han, Jae-Jun;Kim, Sang-Hyun;Chung, Jin-Taek;Kim, Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.3
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    • pp.405-412
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    • 2013
  • This paper reports the steady-state stresses within the heat affected zone (HAZ) of a welded straight pipe subject to creep. The creep constants and exponent are varied systematically to see the effect of various mismatches in creep properties on the steady-state creep stresses, via detailed two-dimensional finite element (FE) creep analyses. The weldments consist of the base metal and weld metal with the HAZ, which are characterized using the idealized power creep laws with the same creep exponent. The internal pressure and axial loading are considered to see the effect of the loading mode. To quantify the creep stresses, a creep mismatch factor is introduced as a function of the creep constants and exponent. It is concluded that the ratio of the section-averaged stresses for a mismatched case to those for an evenmatched case are linearly dependent on the mismatch factor. The results are compared with the FE results, including the Type IV region, as well as the R5 procedure.

Creep Life Prediction of Friction Welded Joints (Cu-Alloy/STS316L) for Nuclear Power Plant (원자력 발전소용 마찰용접재 (Cu합금/STS316L)의 크리프 수명예측)

  • 유인종;공유식;오세규;김선진
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.10a
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    • pp.258-263
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    • 2001
  • In this paper, the real-time prediction of high temperature creep life was carried out for the friction welded joints of dissimilar heat resistintg steels (CulCr0.5Zr-STS316L). Various life prediction methods such as LMP (Larson-Miller Parameter) and ISM (initial strain method) were applied. The creep behaviors of those steels and the welds under static load were examined by ISM combined with LMP at 300, 400 and 50$0^{\circ}C$, and the relationship between these two methods was investigated. A real-time creep life (tsub/r/, hr) prediction equation by initial strain ($\varepsilon_0$, %) under any creep stress ($\sigma$, MP$\alpha$) at any high temperature (T, K) was developed

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High Temperature Creep Life Prediction of Friction Welded Joints by Initial Strain Method and the AE Evaluation (ISM에 의한 마찰용접재(SUH3-SUH35)의 고온크리프 수명예측에 관한 연구)

  • 오세규;이원석
    • Journal of Ocean Engineering and Technology
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    • v.11 no.4
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    • pp.40-48
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    • 1997
  • There are many research results as individual uni-axial tension creep test of heat-resisting materials. However, there are very few about the study on the high temperature creep test for the Initial Strain Method, and especially any study on it about the friction welded joints of SUH3 to SUH35. One of the important concerns is a reliable method of evaluating static creep properties. No reliable method seems available at present to evaluate or predict static creep properties. So, the reliable method to evaluate and predict them by the ISM and AE techniques was made.

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Creep Life Prediction of Aircraft Gas Turbine Material by ISM (ISM에 의한 항공기용 가스터빈 재료의 크리프 수명예측)

  • 공유식;오세규;윤한기
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.05a
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    • pp.108-113
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    • 2001
  • In this paper, the real-time prediction of high temperature creep strength and creep strength and creep life for nickel-based superalloy Udimet 720 (high-temperature and high-pressure gas turbine engine materials) was performed on round-bar type specimens under pure load at the temperatures of 538, 649 and 704$^{\circ}C$. The predictive equation of ISM creep has better reliability than that of LMP and LMP-ISM, and its reliability is getting better for long time creep prediction(10$^3$~10sup/5/h).

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