Heat treatment of nickel based superalloys for turbine blade application: modelling and validation

Cosentino, Francesco (2013). Heat treatment of nickel based superalloys for turbine blade application: modelling and validation. University of Birmingham. Ph.D.

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Abstract

A numerical model has been developed for the simulation of the vacuum heat treatment and high pressure gas quenching used during the manufacture of single crystal turbine blades, of the type used for aeroengine applications. Heat transfer by radiation and forced convection is taken into account to obtain quantitative predictions of the thermal history of the components during ramping-up, holding and gas fan quenching. The uniformity of the temperature is investigated and the effectiveness of the treatment is assessed. Simulations of the quenching process have allowed visualisation of the flow field and prediction of the local quench rate as a function of the furnace parameters. The results of the modelling have been validated against thermocouple measurements made on laboratory-scale vacuum furnace with many of the characteristics of the type used in industrial production. The modelling methodology is extended to industrial scale processes via a multi-scale decomposition approach. The effect of quench rate on the microstructure of CMSX-10 has been characterised using scanning electron microscopy. It is shown that the precipitate size distribution correlates directly with the local quenching rate. To understand the influence of the microstructure on creep performance, two structures with different average \(\gamma\)’ size have been tested in creep over a wide range of temperatures and applied stress levels. Particularly in the low temperature / high stress regime, the size of the precipitates markedly determines the creep performance observed.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):