Journal Published Online: 18 October 2010
Volume 39, Issue 3

Criteria for Small Scale Creep Testing Condition and Estimation of

CODEN: JTEVAB

Abstract

As new creep resistant materials are developed for the temperature range of 800–1100°C, the improved creep properties sometimes require the modification of the conventional approaches in high temperature life assessment procedures which have been applied for low alloy steels and chromium steels usually used in the temperature range of 500–650°C. In this study, finite element analyses were carried out by using the creep properties of a gas turbine material to establish the small scale creep testing requirements and to propose a corrected Ct estimation scheme. The maximum allowable creep zone size was estimated through the analogy between the small scale yielding conditions and the small scale creep conditions. The maximum time during which the small scale creep condition holds was also defined. The creep zone boundary with the definition of εce was more suitable for Ct estimation than that with the definition of εc=0.002, since it was easy to find a proper correction function by applying the former definition. The newly estimated value of β r̃ c =1/7=1/12 was derived for determining Ct instead of the conventional value of β r̃ c =1/7.5. Excellent correlations were shown between the estimated Ct values obtained with the new β r̃ c and the finite element calculated Ct values in all creep condition ranges. This result strongly supports the validity of the suggested small scale creep criterion and the new correction value β r̃ c =1/12 proposed in this study.

Author Information

Wha Ma, Young
Dept. of Mechanical Engineering, Chung Ang Univ., Seoul, Korea
Yoon, Kee
Dept. of Mechanical Engineering, Chung Ang Univ., Seoul, Korea
Pages: 7
Price: $25.00
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Details
Stock #: JTE102920
ISSN: 0090-3973
DOI: 10.1520/JTE102920