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Title:Modelling of thermo-mechanical fatigue behavior in superalloys
Author(s):Kadioglu, Yavuz
Doctoral Committee Chair(s):Sehitoglu, Huseyin
Department / Program:Mechanical Science and Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Mechanical
Engineering, Materials Science
Abstract:Thermo-mechanical fatigue (TMF) and isothermal fatigue (IF) behavior of coated and uncoated Mar-M247 and, uncoated Mar-M246 was studied. The Mar-M247 was coated with Alpak-S1. The coating consists of a manganese and Aluminium powder slurry that is applied by painting, dipping, or spraying with an air brush.
Thermo-mechanical experiments for coated Mar-M247 were conducted under T$\sb{\rm min}$ = 500$\sp\circ$C and T$\sb{\rm max}$ = 871$\sp\circ$C conditions. Both out-of-phase and in-phase strain-temperature phasing conditions were considered. Isothermal experiments were conducted at 500$\sp\circ$C and 871$\sp\circ$C. Comparison with the uncoated Mar-M247 showed that fatigue lives of coated material could be lower than the uncoated material and the difference was as much as four folds in some cases. For uncoated Mar-M247, only thermo-mechanical out-of-phase experiments were conducted. The temperature limit considered was T$\sb{\rm min}$ = 500$\sp\circ$C and T$\sb{\rm max}$ = 1038$\sp\circ$C. SEM, Microprobe and Auger spectroscopy were used to gain insight into oxidation effects at high temperature.
An experimental program for Mar-M246 was also carried out. Due to the coarse grained structure, the stress-strain response indicates variation from specimen to specimen in some cases. The effect of this variation on life does not appear significant, except at smaller strain ranges.
A numerical method is also developed to estimate the stress field due to a surface inhomogeneity in an elastic half space. The technique is based on Eshelby's equivalent inclusion method. The results were used in developing a life prediction methodology for the coated superalloys.
Issue Date:1992
Rights Information:Copyright 1992 Kadioglu, Yavuz
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9215833
OCLC Identifier:(UMI)AAI9215833

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