|Title||Effect of Oxygen Potential on Crack Growth in Alloys for Advanced Energy Systems|
|Year of Publication||2009|
|Authors||Benz, JK, Kim, JH, Ballinger, R|
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.