ISSN: 1945-7553
CODEN: JTEVAB
Page Count: 7

Dynamic Loading Fracture Tests of Ferritic Steel Using the Direct Current Potential Drop Method

Oh, YJ
Graduate students and Associate Professor, Seoul National University, Seoul,

Kim, JH
Graduate students and Associate Professor, Seoul National University, Seoul,

Hwang, IS
Graduate students and Associate Professor, Seoul National University, Seoul,

(Received 26 January 2001; accepted 18 January 2002)

Abstract

To apply the leak-before-break concept to nuclear piping, the dynamic strain aging of low alloy steel materials has to be considered. For this goal, J-R tests are needed over a range of temperatures and loading rates, including rapid dynamic loading conditions. In dynamic J-R tests, the unloading compliance method cannot be applied and usually the direct current potential drop (DCPD) method is used. But, the DCPD method is known to have a problem in defining the crack initiation point due to a potential peak that arises in the early part of loading of ferromagnetic materials. In this study, the characteristics of measured DC potential peaks were investigated for SA106 Gr. C piping steels, and the definition of crack initiation point was determined by backtracking from the physically-measured final crack length. It is proposed that this technique could be applied as an improved DCPD method applicable for the dynamic loading J-R test.

Keywords:
leak-before-break, direct current potential drop, dynamic loading, backtracking, low alloy steel, dynamic strain aging, rapid loading

Paper ID: JTE12309J
DOI: 10.1520/JTE12309J
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