Thesis
Eta (η) phase precipitation during forging and heat treatment of ATI 718Plus®
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2023
- Thesis identifier
- T16601
- Person Identifier (Local)
- 201374736
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- ATI 718Plus components are heat treated to optimised proportions of γ’ and η phases. η phase is utilised in controlling the grain size during hot working processes. When η phase is fully solutioned, the grain size is free to increase, and the material properties can become detrimental. In this study, the aims and objectives were to study the effect of strain and strain rate on the precipitation kinetics of η phase at a temperature range between 925°C to 975°C, at strains between 0 and 0.4 and strain rates of 0.1 s-1 and 0.01 s-1. In addition, the effect of the initial grain size on η phase precipitation kinetics was also studied at the same temperature, strain and strain rate ranges. The η phase at the equilibrium state was studied too, at a temperature range of 850°C to 975°C. TTT diagrams were produced for the η phase in strain-free recrystallised material, deformed material, and larger initial grain size material. Also, the equilibrium η phase content, aspect ratio, length and width were determined. The η phase precipitate aspect ratio, length and width were investigated in the strain-free recrystallised material and in the larger initial grain size material. Some of the key findings that were observed were: • Induced strain considerably hastens the η phase precipitation kinetics in comparison to that in the strain-free recrystallised material. No substantial difference was observed between the strain levels explored in this study. Increasing the strain rate has the effect of making the η phase precipitation kinetics faster in comparison to a slower strain rate. • Increasing the initial grain size produces slower η phase precipitation kinetics, Interestingly, with the same study, incrementally increasing the strain also increases the η phase precipitation kinetics between the strain levels. It is hoped that the findings from this study will assist in the manufacture of components made with ATI 718Plus with optimised microstructures fit for application.
- Advisor / supervisor
- Corney, Jonathan
- Jansen, Yann
- Rahimi, Salaheddin
- Nouveau, Sebastien
- Resource Type
- DOI
Relations
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PDF of thesis T16601 | 2023-06-07 | Public | Download |