Review of rejuvenation process for nickel base superalloys

Combustion turbine components exposed to elevated temperatures and high stresses are subject to periodic replacement as a result of mechanical property degeneration to levels below that required for continued safe operation. In view of the very significant cast associated with replacement components there has been much interest in the rejuvenation of parts. This report reviews published literature on the rejuvenation of nickel base superalloys. The restoration of microstructure and properties to levels equivalent to the original material have been achieved with the use of reheat treatment alone or recovery cycles incorporating both hot isostatic pressing and reheat treatment. The majority of the literature considers the restoration of creep properties, although some success in the rejuvenation of fatigue properties has also been reported. (C) 2001 Siemens Westinghouse Power Corp.