Microstructural evolution of a delta containing nickel-base superalloy during heat treatment and isothermal forging
Materials Science and Engineering: A
MetadataShow full item record
Mignanelli, P., Jones, N., Perkins, K., Hardy, M., & Stone, H. (2014). Microstructural evolution of a delta containing nickel-base superalloy during heat treatment and isothermal forging. Materials Science and Engineering: A, 621 265-271. https://doi.org/10.1016/j.msea.2014.10.071
The next generation of aerospace gas turbine engines need to operate at higher temperatures and stresses to improve their efficiency and reduce emissions. These operating conditions are beyond the capability of existing nickel-base superalloys requiring the development of new high temperature materials. Controlling the microstructures of these new materials is key to obtaining the required properties and therefore, it is critical to understand how these alloys respond to processing and heat treatment. Here, the microstructural evolution of V207M, a new δ containing, nickel-base superalloy, has been investigated following heat treatment and forging. The solvus temperatures of the γ′ and δ phases, determined by differential scanning calorimetry and microscopy, were found to be ~ 985 and ~ 1060 ˚C respectively. Isothermal forging of the alloy was conducted at 1000, 1050 and 1100 ˚C, corresponding to different volume fractions of retained δ. Considerable softening was observed prior to steady state flow when forging at 1000 ˚C, whilst only steady state flow occurred at 1050 and 1100 ˚C. The steady state flow process was believed to be dominated by dynamic recovery in the γ phase, with an activation energy of 407 kJ.mol-1. Samples that exhibited flow softening also showed a significant change in the orientation of the δ precipitates, preferentially aligning normal to the forging axis, and this reorientation was thought to be the cause of the observed flow softening.
nickel-base superalloys, thermomechanical processing, electron microscopy, microstructure
The authors would like to acknowledge M. Shakib for assistance with the forging and the EPSRC/Rolls-Royce Strategic Partnership for supporting this work through EP/H022309/1 and EP/H500375/1.
UNIVERSITY OF BIRMINGHAM (FB EPSRC) (EP/H022309/1)
External DOI: https://doi.org/10.1016/j.msea.2014.10.071
This record's URL: https://www.repository.cam.ac.uk/handle/1810/246344
Attribution 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by/2.0/uk/
Recommended or similar items
The following licence files are associated with this item: