Electrical Potential Drop and Notch Opening Displacement Methods for Detecting High Temperature Low Cycle Fatigue Cracks of Circumferential Notched Specimens

Abstract

This paper assesses the accuracy of the crack initiation detection methods for type 304 SS circumferential notched specimens subjected to strain and stress controlled low cycle fatigue loads at 873 K in air. The methods examined were DC potential drop method (PDM) and the maximum stress criterion in the strain controlled test while they were DC potential drop method and the minimum notch opening displacement method (NOD) in the stress controlled test. The DC potential method and the minimum notch opening displacement method were proved to have a sufficient accuracy for the detection of crack initiation while the maximum stress criterion has less accuracy. The crack length detection based on DC potential drop method is also discussed.