####
J. Japan Inst. Metals, Vol. 69, No. 8 (2005),

pp. 735-738

##
Applicability of a Creep Constitutive Equation for Ni-Base Superalloys Using Structural Parameters at Different Temperature-Stress Conditions

**
Hitoshi Izuno, Tadaharu Yokokawa and Hiroshi Harada
**

National Institute for Materials Science, Materials Engineering Laboratory, High Temperature Materials Group, Tsukuba 305-0005

#### Abstract:

A new creep constitutive equation for Ni-base superalloys with good reproducibility of high temperature-low stress condition (1100°C/137 MPa) has been proposed. In this paper, an application of the creep constitutive equation for creep curves of lower temperature-high stress condition (900°C/392 MPa) is discussed. Under the condition, it seems evidently that creep curves have no logarithmic elongation at early secondory creep stage, thus a parameter of the creep constitutive equation contained in the logarithmic part decreases to zero. Muti-regression analysis for each parameter of the creep constitutive equation with gamma-prime composition, structural parameters as explanatory variables have been carried out in order to obtain a comparison of the result of multi-regression analysis of high-temperature low-stress condition. Predictions of creep curves at different temperature-stress conditions by interpolation is also discussed.

(Received 2005/4/22)

#### Keywords:

nickel-base superalloy, creep curve prediction, creep constitutive equation, structural parameter, multi regression analysis

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