The Use of Heat-Treatment to Recover the Creep Properties of Nimonic 115 After High-Temperature Creep

Davies, Peter W. F.; Dennison, J.P.

doi:10.1179/030634575790444793

Cited by 12 publications

(2 citation statements)

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“…Depending on how far creep was allowed to proceed prior to annealing, and also on the annealing parameters, the creep life was extended by varying degrees. In one experiment, fracture only occurred after eleven creep-anneal cycles which corresponded to a rupture life increase of over 90% [3]. In practice, blades may require more than 3 rejuvenations for the total design-life of their plant, but are frequently retired for other causes, such as impact damage, before undergoing 3 or more rejuvenations.…”

Section: Service Experiencementioning

confidence: 99%

“…The first studies showing that the creep life of superalloys could be extended were performed on Nimonic 80 during the 1960's [2]. Further studies during the 1970's, examining the effects of heat treatments on higher strength alloys, showed that it was possible to achieve substantial restoration of creep properties through the use of appropriate heat treatment cycles [3,4]. The term "rejuvenation" was first adopted in 1977, when the techniques, including hot isostatic pressing, were first used to restore service exposed turbine blades to a serviceable condition [5].…”

Section: Introductionmentioning

confidence: 99%

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Practical Experience With the Development of Superalloy Rejuvenation

Liburdi¹,

Lowden²,

Nagy³

et al. 2009

Volume 4: Cycle Innovations; Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine

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Material degradation is one of the primary causes of gas-turbine hot section component retirement. This is characterized by microstructural aging and subsequent loss of creep strength. Under the same temperature conditions, the longer components remain in service, the more microstructural degradation occurs. This can be evaluated both through microscopy and stress-rupture tests, quantifying the material strength under high temperature, constant load creep conditions. In an effort to extend component life and reduce replacement part costs, material rejuvenation processes have been developed and implemented over the past few decades. In total over 35 commercial superalloy rejuvenation processes were studied and it was found that many alloys can be successfully rejuvenated but others pose a greater challenge. Issues of grain growth in forged turbine components and recrystallization in single crystal components impose limits on rejuvenation processes and are areas of ongoing development. The feasibility, successes and limitations of material rejuvenation are reviewed in this paper with a particular focus on the following superalloys: GTD111, IN738, and Nimonic 115. Examples of microstructure and stress-rupture life of turbine components in both the service-exposed and rejuvenated condition are presented. Component microstructure is shown to be restored, and the stress-rupture life following rejuvenation is returned to a condition fit for continued service.

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Section: Service Experiencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%