TY - JOUR
T1 - Improvement of omega method for creep life prediction
AU - Maruyama, Kouichi
AU - Nonaka, Isamu
AU - Sawada, Kota
AU - Sato, Hiroyuki
AU - Koike, Jun Ichi
AU - Umaki, Hideo
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1997
Y1 - 1997
N2 - Omega method has been proposed for predicting rupture life from creep strain ε-time t data. The method is based on a linear relation between logarithm of creep rate ε̇ and strain, namely a creep curve without the primary and secondary creep stages. Such a linear relation, however, seldom holds in real creep data. In this paper, the original equation is modified to the following form: ε=ε0 + 1/Ω {In(1 + ζt)-In (1-ηt)} where ε0, Ω, ζ, and η are parameters characterizing a creep curve. The first and second terms in the parentheses describe primary creep and tertiary creep, respectively. The equation is applied to ferritic steels. The four parameters of the equation can uniquely be determined for a creep curve with a curved In ε̇-ε relation. The equation can well reproduce creep curves with a prominent primary creep stage. Because of the high reproducibility, the modified equation can predict rupture life with higher accuracy at an earlier stage of creep than the original equation.
AB - Omega method has been proposed for predicting rupture life from creep strain ε-time t data. The method is based on a linear relation between logarithm of creep rate ε̇ and strain, namely a creep curve without the primary and secondary creep stages. Such a linear relation, however, seldom holds in real creep data. In this paper, the original equation is modified to the following form: ε=ε0 + 1/Ω {In(1 + ζt)-In (1-ηt)} where ε0, Ω, ζ, and η are parameters characterizing a creep curve. The first and second terms in the parentheses describe primary creep and tertiary creep, respectively. The equation is applied to ferritic steels. The four parameters of the equation can uniquely be determined for a creep curve with a curved In ε̇-ε relation. The equation can well reproduce creep curves with a prominent primary creep stage. Because of the high reproducibility, the modified equation can predict rupture life with higher accuracy at an earlier stage of creep than the original equation.
KW - Constitutive creep equation
KW - Creep curve
KW - Creep rupture
KW - Heat affected zone
KW - Heat resisting steel
KW - High temperature
KW - Life assessment
KW - Omega method
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U2 - 10.2355/isijinternational.37.419
DO - 10.2355/isijinternational.37.419
M3 - Article
AN - SCOPUS:0030714263
VL - 37
SP - 419
EP - 423
JO - Transactions of the Iron and Steel Institute of Japan
JF - Transactions of the Iron and Steel Institute of Japan
SN - 0915-1559
IS - 4
ER -