Speaker
Description
Ni-Fe superalloys are used for the fabrication of forged components for turbine applications with a maximum service temperature of around 600°C (1100°F) due to their excellent properties retention at elevated temperatures such as strength, corrosion, creep (time-dependent deformation), stress-rupture (time to fracture) and thermal stability. However, the trade-off from a manufacturing perspective is that the processing window demands careful control of hot working and heat treatment parameters to develop an optimal microstructure, reduce the presence of detrimental phases and ensure target mechanical properties.
The processing of this material may include combinations of remelting techniques along with open-die forging, ring rolling, heat treatment, and machining.
On this basis, the present work explores the hot workability window of a Ni-Fe superalloy with a composition of Ni 40-45%, Cr 11-14%, Mo 5-7%, Ti 2.35-3.10%. in terms of the resultant microstructure by using different temperatures under industrial scale conditions. This type of superalloy is strengthened primarily by the precipitation of Gamma prime γ'[Ni₃(Ti,Al)] an intermetallic strengthening phase within a face-centered cubic (FCC) Gamma (γ) matrix among other metallurgical features.
To approach this from a reliable yet practical perspective, the wedge-forging test was selected. In this test, a wedge-shaped piece made of the selected melt is machining from the starting material for the forging process and forged (upset) between flat parallel dies. This technique as a whole allows the effects of the production environment to be evaluated. The outcome of the test is a strain gradient across the test specimen under the influence of different temperatures.
The findings of this work will provide a technical basis for optimizing microstructure for the manufacturing of Ni-Fe high temperature alloy components, targeting specific requirements. Finally, the experimental results are expected to be validated by means of FEA mathematical models.
| Speaker Company/University | FRISA |
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