Numerical Modelling of Stress and Strain Evolution during Solidification of a Single Crystal Superalloy

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During the manufacture of turbine blades from single crystal nickel-based superalloys by investment casting, recrystallisation can occur during solution heat treatment. The introduction of grain boundaries into a single crystal component is potentially detrimental to performance, and therefore manufacturing processes and/or component geometries should be chosen to prevent their occurrence. In this work, numerical models have been designed to enable a predictive capability for the factors influencing recrystallisation to be constructed. The root cause is plasticity on the microscale caused by differential thermal contraction of metal, mould and core; when the plastic deformation is sufficient, recrystallisation can take place subsequently. The models take various forms. First, one-dimensional models based upon static equilibrium have been produced – our calculations indicate that plastic strain is likely to take place in two temperature regimes: by creep between 1150°C and 1000°C and by tensile (time-independent) strain below 650°C. The idea of a strain-based criterion for recrystallisation is then proposed. Second, more sophisticated three-dimensional calculations based upon the finite element method are carried out. Our predictions are compared critically with experimental information.

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Edited by:

M. Heilmaier

Pages:

204-209

DOI:

10.4028/www.scientific.net/AMR.278.204

Citation:

C. Panwisawas et al., "Numerical Modelling of Stress and Strain Evolution during Solidification of a Single Crystal Superalloy", Advanced Materials Research, Vol. 278, pp. 204-209, 2011

Online since:

July 2011

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