A Comparison of the C-Ring Test and the Jones Test as Standard Practice Test Methods for Studying Stress Corrosion Cracking in Ferritic Steels

Abstract

Creep-strength-enhanced-ferritic (CSEF) steels have been widely implemented as water wall alloy materials in the coal-fired power industry for many years. The stress corrosion cracking (SCC) behavior of this class of materials is currently of significant interest to the industry due to recent failures. To better understand the test methods used to characterize SCC behavior in the laboratory, three representative CSEF alloys (UNS K40712, K30736, and K92460, also known in the industry as T23, T24, and T92 respectively) were subjected to two SCC test protocols: the ‘Jones Test’ set forth in DIN 50915, and the C-ring SCC test set forth in ASTM G38-01. Samples were tested in either the as-received (normalized + tempered) condition or in the normalized condition (quenched from 1065⁰C). Samples were exposed to aerated water in one test case and de-aerated water in a second test case for a period of 7 days at 200⁰C. It was found that for both test protocols, the normalized condition with aerated water led to severe cracking for all three alloys, whereas no evidence of cracking was found for the other conditions.