Hot forming behavior of a modified Ni-Cr superalloy
2020
Carreño, Fernando | Carsí, Manuel | Llaneza, Jaime | Ruano, Oscar Antonio | Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
The hot working behavior of a 38Ni-21Cr based superalloy was studied. Torsion tests at strain rates between 2 and 20 s-1 and temperatures between 1 123 and 1 473 K were conducted. A fine microstructure of about 6-10 µm grain size and small TiC particles were observed after torsion tests at 1 473 K and 4 s-1. The results of these tests were analyzed using MATLAB and MS EXCEL programs to obtain the parameters of the Garofalo equation able to correlate the experimental data with a single equation. Stress exponent values much higher than 5 and a high activation energy for deformation suggest that the deformation is controlled by a slip creep mechanism characteristic of reinforced materials. The optimum forming temperatures at different strain rates were determined by means of the second Lyapunov stability equation. An optimum stability temperature of 1 643 K (1 370 °C) at 10 s-1 is determined.
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