Speaker
Description
The development of Very High Bypass Ratio (VHBR) aero-engines can contribute to fulfilling the goals of the Sustainable and Green Engines (SAGE) programme. The potential environmental benefits of the new
aero-engine concept require increased speed and loading capabilities as compared to today’s solutions.
This paper describes the development of an advanced temperature resistant, corrosion tolerant steel for hybrid bearing rings for aero-engine applications. The target was for an increase in the hybrid bearing load capacity by 15% plus an increase of 25% in the rotation speed capability.
In order to achieve the load capacity target, the steel rings of the hybrid bearing needed to be improved in terms of hardness, specifically hot hardness. The composition of Pyrowear 675 was taken as a basis for the development and the alloying philosophy centred around the use of cobalt because of its beneficial effects on hot hardness.
A series of small scale test melts were made with the initial compositions being modelled using ThermoCalc. The heat treatment response of the initial melts was used to define further test melts to refine the composition to a final target composition for an industrial 16 ton VIM-VAR melt.
The toughness properties of the core microstructure of the VIM-VAR steel have been assessed, as has the response to thermochemical heat treatments such as carburising and carbonitriding. The hot hardness properties and tribological properties will be compared to baseline aerospace steel and heat treatment combinations such carburised M50NiL.
Rolling contact fatigue testing of components has shown good results compared to existing aerospace steel and heat treatment solutions.
The next steps towards implementation of the concept will be outlined.
| Speaker Country | The Netherlands |
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