Modeling stress accelerated grain boundary oxidation (SAGBO) in INCOLOY alloy 908
Name
64387820-MIT.pdf
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2.04 MB
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Checksum (MD5)
53f2f697b183edf9e0d48b907a817b8d
Author(s)
Soontrapa, Chaiyod
Advisor(s)
Ronald G. Ballinger.
Alternative Title
Modeling SAGBO in INCOLOY alloy 908
Date Issued
2005
Publisher
Massachusetts Institute of Technology
Abstract
This study explores the possibility of extending the Ph.D. work of Yan Xu on copper-tin alloys (University of Pennsylvania, 1999) to model stress accelerated grain boundary oxidation (SAGBO) in INCOLOY alloy 908. The steady state model involves the embrittlement along the grain boundary due to oxygen diffusion with the concentration gradient and the stress field ahead of the crack tip as the driving forces. As oxygen forms brittle phases with the segregates in the grain boundary, it reduces the cohesive strength of the grain boundary and causes intergranular cracking in the material. The extensions to the original model include (1) dependence of oxygen concentration at crack tips on oxygen partial pressure and (2) a new creep law specific to nickel-based superalloys. While the steady state model correctly indicates temperature as one of three leading factors in SAGBO, it fails to capture the effects of the two remaining factors: applied loading and oxygen partial pressure.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005.
Includes bibliographical references (p. 57-59).
Subjects
Materials Science and Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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