Abstract
Thermal fatigue failure of pipes induced by fluid temperature change is one of interdisciplinary issues for long term structural reliability. In this work a special focus was put on the effect of thermal and loading histories on high cycle fatigue crack growth behavior. In order to get basic understanding on this article the fatigue crack propagation tests were carried out in a low alloy steel which experienced several kind of loading and/or thermal histories. Both the effects of stress ratio, test temperature on the fatigue crack threshold, and the change in the threshold depending on the thermo-mechanical loading histories, were experimentally investigated. It was shown that the thermo-mechanical loading history left its effect along the prior fatigue crack wake resulting in the change of fatigue crack threshold. Some discussions are made on how this type of loading history effect should be treated from engineering point of view.
