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Use of Slow Strain Rate Tensile Testing to Assess the Ability of Several Superalloys to Resist Environmentally-Assisted Intergranular CrackingIntergranular fatigue crack initiation and growth due to environmental degradation, especially at notched features, can often limit the fatigue life of disk superalloys at high temperatures. For clear comparisons, the effects of alloy composition on cracking in air needs to be understood and compared separately from variables associated with notches and cracks such as effective stress concentration, plastic flow, stress relaxation, and stress redistribution. The objective of this study was to attempt using simple tensile tests of specimens with uniform gage sections to compare the effects of varied alloy composition on environment-assisted cracking of several powder metal and cast and wrought superalloys including ME3, LSHR, Udimet 720(TradeMark) ATI 718Plus(Registered TradeMark) alloy, Haynes 282(Trademark), and Inconel 740(TradeMark) Slow and fast strain-rate tensile tests were found to be a useful tool to compare propensities for intergranular surface crack initiation and growth. The effects of composition and heat treatment on tensile fracture strain and associated failure modes were compared. Environment interactions were determined to often limit ductility, by promoting intergranular surface cracking. The response of various superalloys and heat treatments to slow strain rate tensile testing varied substantially, showing that composition and microstructure can significantly influence environmental resistance to cracking.
Document ID
20140017059
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Gabb, Timothy P. (NASA Glenn Research Center Cleveland, OH United States)
Telesman, Jack (NASA Glenn Research Center Cleveland, OH United States)
Banik, Anthony (ATI Allvac Monroe, NC, United States)
McDevitt, Erin (ATI Allvac Monroe, NC, United States)
Date Acquired
December 8, 2014
Publication Date
September 28, 2014
Subject Category
Metals And Metallic Materials
Aircraft Propulsion And Power
Report/Patent Number
GRC-E-DAA-TN14010
Meeting Information
Meeting: International Symposium on Superalloy 718 and Derivatives
Location: Pittsburgh, PA
Country: United States
Start Date: September 28, 2014
End Date: October 1, 2014
Sponsors: Minerals, Metals and Materials Society
Funding Number(s)
WBS: WBS 473452.02.03.05.04.01.01
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
fatigue(materials)
oxidation
Heat resistant alloys

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