Effect of Oxygen Potential on Crack Growth in Alloys for Advanced Energy Systems

TitleEffect of Oxygen Potential on Crack Growth in Alloys for Advanced Energy Systems
Publication TypeBook
Year of Publication2009
AuthorsBenz, JK, Kim, JH, Ballinger, R
Abstract

The effect of oxygen partial pressure on fatigue and SCC growth rates in alloy 617 has been studied using both static and fatigue loading @ 650 degrees C over the oxygen partial pressure range 10(-19)-10(-2) atm. Tests were conducted at either constant stress intensity factor, K, for static conditions or constant Delta K in fatigue. Oxygen concentration was measured on both the inlet and outlet as well as in-situ with a probe located directly at the specimen surface. For fatigue loading the crack path was observed to be transgranular but crystallographic with a decreasing growth rate as the oxygen concentration decreased. However, for static loading the crack path shifted to intergranular and exhibited an increasing crack growth rate with decreasing oxygen concentration.