Rejuvenation heat treatment's influence on the microstructure and properties of superalloys

Abstract

Rejuvenation heat treatment is an important technology to restore damaged microstructure and properties of superalloys. This investigation is conducted to figure out the effect of rejuvenation heat treatment on the superalloys. The microstructure and micro-hardness of K002 and DZ125 superalloys after different heat treatment procedures were evaluated. The results show that the heating temperature mainly affects the solubility of the carbides and γ′ phases, while the cooling rate has an effect on the morphology of secondary γ′ phase. Owing to the transition of carbides during the work process, rejuvenation heat treatment temperature has little effect on the amount of carbides in damaged alloys. Suggestions for rejuvenation heat treatment are proposed.

Lifetime extension prediction of the rejuvenated first stage gas turbine blades

“…Consequently, important costs saving can be achieved by aged buckets life extension through RHTs through reducing their degradation and boosting up their usable life [11]. As reported by H. Yang et al [12], to achieve a good blade structure with two-phase γ′ structure utilise vacuum heat treat furnace for the RHTs process, in order to erase and reform the microstructure of GTD-111 buckets after long-term service. Thus, the secondary γ′ precipitates changed to a more cuboidal morphology, which provides for buckets creep life revitalising, hardness properties improvement [13].…”