Research Papers

Creep Characterization of Ni-Based Superalloy IN-792 Using the 4- and 6-θ Projection Method

[+] Author and Article Information
S. A. Sajjadi

e-mail: sajjadi@um.ac.ir

A. Rezaee-Bazzaz

Department of Metallurgical and
Materials Engineering,
Faculty of Engineering,
Ferdowsi University of Mashhad,
Mashhad, Iran

1Corresponding author.

Contributed by the Materials Division of ASME for publication in the JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY. Manuscript received December 7, 2012; final manuscript received November 9, 2013; published online December 4, 2013. Assoc. Editor: Ashraf Bastawros.

J. Eng. Mater. Technol 136(1), 011006 (Dec 04, 2013) (7 pages) Paper No: MATS-12-1277; doi: 10.1115/1.4026035 History: Received December 07, 2012; Revised November 09, 2013

This paper studies the accuracy of a technique which is capable of predicting and modeling a wide range of creep life in Ni-based superalloys. The θ-projection method was applied to characterize the creep behavior of the Ni-based superalloy IN-792 at 800 °C. Constant load creep tests have been carried out over a wide range of loads at the constant operating temperature. Creep curves were fitted using either 4-θ or 6-θ equation by the use of a nonlinear least-square technique. The results showed that both 4- and 6-θ projection parameters revealed a good linearity as a function of stress. Comparison of experimental creep curves with those predicted using both of the utilized θ-projection techniques showed that the techniques fit the experimental data at high strain values very well while the 6-θ approach describes much better the creep curves at low strain region.

Copyright © 2014 by ASME
Topics: Creep , Superalloys , Stress
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Grahic Jump Location
Fig. 1

(a) As-cast microstructure of IN-792 with coarse γ′ and eutectic γ-γ′ phase particles; (b) microstructure after solution and aging treatment with cuboidal γ′ precipitates

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Fig. 2

Experimental creep curves obtained at constant temperature of 800 °C and at different stresses

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Fig. 3

Results of the experimental data and fitted curve at 800 °C with 4-θ projection with the stress (a) 550, (b) 525, (c) 500, (d) 475, and (e) 450 MPa

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Fig. 4

The variation of (a) θ1, (b) θ2, (c) θ3, and (d) θ4 with stress at 800 °C with 4-θ projection

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Fig. 5

Result of experimental data and fitted curve at 800 °C with 6-θ projection with the stress: (a) 550, (b) 525, (c) 500, (d) 475, and (e) 450 MPa

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Fig. 6

The variation of (a) θ1, (b) θ2, (c) θ3, (d) θ4, (e) θ5, and (f) θ6 with stress at 800 °C with 6-θ projection

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Fig. 7

Directed and rafted of γ′ precipitates during: (a) the second stage, and (b) third stage of creep at 800 °C



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