Evaluation of J-R Curve Testing of Nuclear Piping Materials Using the Direct Current Potential Drop Technique.

摘要

A method is described for developing J-R curves for nuclear piping materials using the D.C. Potential Drop (DCPD) technique. Experimental calibration curves were developed for both three point bend and compact specimen geometries using ASTM A106 steel, a type 304 stainless steel and a high strength aluminum alloy. These curves were fit with a power law expression over the range of crack extension encountered during J-R curve tests (0.6 a/W to 0.8 a/W). The calibration curves were insensitive to both material and sidegrooving and depended solely on specimen geometry and lead attachment points. Crack initiation in J-R curve tests using DCPD was determined by a deviation from a linear region on a plot of COD vs. DCPD. The validity of the criterion for ASTM A106 steel was determined by a series of multispecimen tests that bracketed the initiation region. A statistical differential slope procedure for determination of the crack initiation point is presented and discussed.