Correlating microstructure recovery to rejuvenation of high-temperature creep properties in a crept single-crystal superalloy

Abstract

Academic debate still exists as to whether and how multi-scale microstructure recovery is linked to creep properties rejuvenation of superalloys. We propose a rejuvenation heat treatment (RHT) for one single-crystal superalloy crept at 1100 °C/120 MPa, by which the degraded phase- and dislocation-microstructure can be recovered to standard heat treatment one. Despite experiencing different plastic deformation, such recovered microstructure leads to nearly a fixed 20% improvement in creep life. Through triple creep-RHT-creep cycle tests, the complete rejuvenation of creep life after special creep time has been validated, while the plastic deformation limit increases, where creep properties recoverability remains.

Keywords

• Rejuvenation heat treatment
• single-crystal superalloy
• dislocation
• microstructure recovery
• high-temperature creep