Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Thermal diffusivity and surface mechanical properties of the plasma nitrided Hastelloy X superalloy
Submission Author:
Regiane Gordia Drabeski , PR
Co-Authors:
Regiane Gordia Drabeski, Rafael Fillus Chuproski, Isabel Borges da Rocha, Daniele Dias, Anderson Geraldo Marenda Pukasiewicz, Gelson B. de Souza
Presenter: Regiane Gordia Drabeski
doi://10.26678/ABCM.ENCIT2022.CIT22-0126
Abstract
Abstract. The nickel-based superalloy Hastelloy X were DC plasma nitrided for the first time in this study. Structure and mechanical properties of the nitrided surfaces were compared with the respective bulks, subjected only to heating. The nitriding produced the expanded austenite phase (mainly at 400 °C) and metal nitrides, such as Cr2N (in the higher temperatures, 500-700 °C). The nitrogen diffusion in the matrix obeyed a complex and dynamic correlation with temperature due to the competitive nitrogen retention in interstices and precipitates. The thickest layer (8 μm) and nitrogen amount (20 at%) were attained at the 600 °C nitriding. The overall thermal effect in the superalloy bulk was the precipitation of S-phase at 700 °C, for which hardness increased from 3.8 to 4.3 GPa. The nitrogen inlet yielded strengthened cases, with hardness values reaching 10.5 GPa (at 400 °C) and ~14 GPa (at the remaining conditions). The thermal diffusivity of the superalloy was 1.8610-6 m²/s. After the nitriding process, the effective thermal diffusivity values increased with the treatment temperature, reaching 4.3110-6 m²/s at 700°C the maximum nitriding temperature, a value similar to that of commercially available Chromel. These results are of intrinsic importance for the load bearing capacity and heating dissipation of the modified surfaces.
Keywords
Photoacoustic measurement, Phase-lag, nanoindentation, elastic modulus
