Conference Paper
Potential implications of step loading in impression creep testing
Authors:
A. Bridges ,
Electric Power Research Institute, 1300 W. W.T Harris Blvd, Charlotte, NC 28262 USA
D. Purdy
Electric Power Research Institute, 1300 W. W.T Harris Blvd, Charlotte, NC 28262 USA
Abstract
The small sample impression creep test method has recently been of interest, as it can give a good indication of expected creep rates in uniaxial creep testing with minimal use of material. The compressively loaded test has also been shown to provide accurate results under multi-step loading conditions for a low alloy steel (½Cr½Mo¼V) to further extract value from a single test specimen. The Electric Power Research Institute (EPRI) has conducted step tests (step temperature and step loading changes) on another low alloy steel (Grade 22), as well as a tempered martensitic 9 Cr steel (Grade 91). Results have shown that there may be potential problematic areas when conducting step-up and step-down steps in these materials. Additional posttest evaluations have shown that material effects, such as strain hardening and strain softening, may add additional complexities when comparing strain rates of multi-stepped loaded stain rates. Hardness testing on posttest impression creep specimens have confirmed strain softening of tempered martensitic Grade 91 and no observed effect for an ex-service Grade 22 alloy. These findings have shown that careful considerations must be made before using creep rates obtained from multi-stepped loaded tests in situ of single loaded tests.
How to Cite:
Bridges, A. and Purdy, D., 2018. Potential implications of step loading in impression creep testing. Ubiquity Proceedings, 1(S1), p.9. DOI: http://doi.org/10.5334/uproc.9
Published on
10 Sep 2018.
Peer Reviewed
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