Microstructure Refinement to Improve Creep-Fatigue Resistance

Large precipitates in 316H PM-HIP parts result in poor creep-fatigue performance, limiting their application for nuclear reactors. PM-HIP components can lower the cost of new reactor designs because the process is generally cheaper and quicker than the traditional methods (casting, forging) of manufacturing large netshape parts. However, due to the elevated temperatures experienced by the parts in reactor design, PM-HIP parts need improvement in their creep-fatigue performance to meet the guidelines in ASME Sec. III, Div. 5. Electropulse Aging Treatment (EAT) is a process that can be used to treat the final parts, removing large precipitates and therefore improving the creep-fatigue performance. This process will be used in Phase I to treat different 316H PM-HIP samples, which will then undergo creep-fatigue testing to validate their improved performance. A Phase II and III program would be focused on scaling the EAT process to larger parts with different geometries.