Critical assessment 31: on the modelling of tertiary creep in single-crystal superalloys

ABSTRACT

Modelling of tertiary creep in single-crystal superalloys – operative over the majority of the temperature/stress regime of relevance – is assessed. Traditional, empirical approaches are useful for the prediction of component life; a modern trend is for more physically faithful models which account for microstructure and alloy composition. Calculations are made using different methods, to identify advantages/disadvantages, in an effort to approach best practice. The predictions are tested against experimental data. The creep resistance can be estimated to within approximately one-half of a Larson–Miller parameter, from an input of alloy composition, deformation conditions, and estimates of microstructural parameters, rate laws (and parameters therein), and physical constants. Different merit indices are considered to identify the most appropriate for compositional optimisation.

KEYWORDS:

• Single-crystal nickel-based superalloys
• creep damage
• continuum damage mechanics
• creep modelling
• alloy design

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Sabin Sulzer  http://orcid.org/0000-0001-6647-3538

Additional information

Funding

Financial support from Siemens Industrial Turbomachinery AB (Finspång, Sweden) is gratefully acknowledged. RR acknowledges funding from the Engineering and Physical Sciences Research Council (EPSRC) [grant number EP/M005607/01].