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AD730TM is a newly developed Ni-based superalloy for turbine disk applications produced by cast and wrought processes. Conventional ingot-to-billet conversion is an expensive and very complex operation. Because of the difficulties to achieve a uniform strain for recrystallization, large unrecrystallized grains are retained along this process. Heterogeneities of grain size have a negative impact on subsequent forging processes as well as ultrasonic inspectability of the destination part. The main aim of this work is to analyse the impact of both forging direction (billet, cogging) and strain (ε = 0.3 - 2) on the microstructural evolution of AD730 at subsolvus temperatures from a semi-finished product (billet) under conditions representative of both cogging and hot forging operations. Special attention to the presence of large unrecrystallized grains was paid. Double truncated cones (DTCs) were hot forged at subsolvus temperatures followed by air cooling. SEM and EBSD analysis were conducted in the as-received (billet) and the as-forged conditions. AD730 alloy presents a complex microstructure characterized by the presence of large unrecrystallized grains, aligned in the billet direction, with remarkable differences in γ’ precipitates distribution as compared to recrystallized structures. The fine distribution of primary γ’ precipitates (pinning effect) plays a key role on grain size control but also on the recrystallization behaviour. Continuous dynamic recrystallization (CDRX) mechanism was found to be operating in the large unrecrystallized grains, promoting the formation intragranular DRX grains and the gradual recrystallization of these grains. Strain presents a strong effect on the microstructural evolution of AD730, increasing the recrystallization fraction and refining the structure. By contrast, no significant effect associated to the forging direction was found. Conditions representative of cogging operations (ε ≤ 0.6) at subsolvus temperatures were translated into large fractions of unrecrystallized structures (strain accumulation).
|Number of pages||13|
|Early online date||5 Oct 2018|
|Publication status||Published - 31 Dec 2018|
- hot forging
- continuous dynamic recrystallization (CDRX)
- gamma precipitates
- EBSD analysis
FingerprintDive into the research topics of 'Impact of forging direction on the recrystallization behaviour of nickel base superalloy AD730 billet material at subsolvus temperatures'. Together they form a unique fingerprint.
- 2 Finished
AFRC_CORE_813: Analysis of the recrystallization behaviour of AD730
1/08/17 → 31/07/18
AFRC_CORE_530: Analysis of the recrystallization behaviour of Ni-based superalloy AD730
1/08/16 → 31/07/17
- 14 Citations
- 1 Poster
Impact of forging direction on the recrystallization behavior of nickel based superalloy AD730 billet material at subsolvus temperaturePerez, M., Dumont, C., Nodin, O. & Nouveau, S., 9 Sep 2018. 1 p.
Research output: Contribution to conference › PosterOpen AccessFile
- 1 Participation in conference
Marcos Perez (Participant)13 Nov 2018 → 15 Nov 2018
Activity: Participating in or organising an event types › Participation in conference