Anomalies in hydrogen enhanced fatigue of a high strength steel

Fatigue crack growth for an HSLA steel was studied with in situ hydrogen charging. The hydrogen effect was highest at low Delta K values. The anomalies in hydrogen effect were found in the relative insensitivity of the crack growth rates to Delta K in a decreasing Delta K test protocol, and in the distinct differences of the crack growth rates for different loading protocols. These anomalies are explained by the hydrogen availability at the crack tip as a function of the test parameters. A t and Delta K based parameter was found to be universally applicable for hydrogen enhanced fatigue irrespective of loading protocol. (C) 2013 Elsevier Ltd. All rights reserved.