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Author Pridemore, Wesley D.
Source SpringerLink
Content type Text
Publisher Springer US
File Format PDF
Copyright Year ©2008
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Chemistry & allied sciences
Subject Keyword Gas turbine ♦ Nickel-based superalloy ♦ Creep ♦ Stress-rupture ♦ Gamma prime (γ′) ♦ Grain boundaries ♦ Interdendritic and creep voiding ♦ Quality Control, Reliability, Safety and Risk ♦ Structural Mechanics ♦ Mechanics ♦ Characterization and Evaluation of Materials ♦ Tribology, Corrosion and Coatings ♦ Materials Science
Abstract Today’s gas turbine engines utilize high volume fraction gamma prime (γ′) strengthened alloys for turbine airfoils, which typically operate at temperatures greater than ∼0.5T $_{m }$of the alloy. At these temperatures and at stresses below yield, time-dependent deformation (creep) of the airfoil can occur and, if left unabated, can result in complete separation of the airfoil. This process is commonly referred to as stress rupture. Insufficient cooling air, unintentional interruptions of cooling air as well as abnormal engine operating conditions are typical causes of stress-rupture failures in gas turbine blade components. Stress-rupture fractures are generally heavily oxidized, tend to be rough in texture, and are primarily intergranular and/or interdendritic in appearance compared to smoother, transgranular fatigue type fractures. Often, gross plastic yielding is visible on a macroscopic scale. Commonly observed microstructural characteristics include creep voiding along grain boundaries and/or interdendritic regions. Internal voids can also nucleate at carbides and other microconstituents, especially in single crystal castings that do not possess grain boundaries. Other signs of overtemperature include partial resolutioning of the γ′ strengthening precipitates, with the remaining volume fraction of γ′ commonly used to estimate blade metal temperatures. This article highlights the visual, fractographic, and metallographic characteristics typically encountered when analyzing stress rupture of turbine airfoils.
ISSN 15477029
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2008-04-30
Publisher Place Boston
e-ISSN 18641245
Journal Journal of Failure Analysis and Prevention
Volume Number 8
Issue Number 3
Page Count 8
Starting Page 281
Ending Page 288

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Source: SpringerLink