Identification of Expanded Austenite in Nitrogen-Implanted Ferritic Steel through In Situ Synchrotron X-ray Diffraction Analyses

Schibicheski Kurelo, Bruna C. E.; Lepienski, Carlos M.; de Oliveira, Willian R.; de Souza, Gelson B.; Serbena, Francisco C.; Cardoso, Rodrigo P.; das Neves, Julio C. K.; Borges, Paulo C.

doi:10.3390/met13101744

Open AccessArticle

Identification of Expanded Austenite in Nitrogen-Implanted Ferritic Steel through In Situ Synchrotron X-ray Diffraction Analyses

by

Bruna C. E. Schibicheski Kurelo

^1,*,

Carlos M. Lepienski

¹

,

Willian R. de Oliveira

²,

Gelson B. de Souza

²

,

Francisco C. Serbena

²,

Rodrigo P. Cardoso

³

,

Julio C. K. das Neves

¹

and

Paulo C. Borges

¹

Postgraduate Program in Mechanical and Materials Engineering, Federal Technological University of Paraná, Campus Ecoville, Curitiba 81280-340, Brazil

²

Laboratory of Mechanical Properties and Surfaces, Department of Physics, State University of Ponta Grossa, Campus Uvaranas, Ponta Grossa 84030-900, Brazil

³

LabMat, Department of Mechanical Engineering, Federal University of Santa Catarina, Campus Trindade, Florianópolis 88040-900, Brazil

^*

Author to whom correspondence should be addressed.

Metals 2023, 13(10), 1744; https://doi.org/10.3390/met13101744

Submission received: 30 June 2023 / Revised: 30 September 2023 / Accepted: 10 October 2023 / Published: 14 October 2023

(This article belongs to the Special Issue Advances in Low-Temperature Nitriding and Carburizing of Stainless Steels and Metallic Materials: Formation and Properties)

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Abstract

The existence and formation of expanded austenite in ferritic stainless steels remains a subject of debate. This research article aims to provide comprehensive insights into the formation and decomposition of expanded austenite through in situ structure analyses during thermal treatments of ferritic steels. To achieve this objective, we employed the Plasma Immersion Ion Implantation (PIII) technique for nitriding in conjunction with in situ synchrotron X-ray diffraction (ISS-XRD) for microstructural analyses during the thermal treatment of the samples. The PIII was carried out at a low temperature (300–400 °C) to promote the formation of metastable phases. The ISS-XRD analyses were carried out at 450 °C, which is in the working temperature range of the ferritic steel UNS S44400, which has applications, for instance, in the coating of petroleum distillation towers. Nitrogen-expanded ferrite (α_N) and nitrogen-expanded austenite (γ_N) metastable phases were formed by nitriding in the modified layers. The production of the α_N or γ_N phase in a ferritic matrix during nitriding has a direct relationship with the nitrogen concentration attained on the treated surfaces, which depends on the ion fluence imposed during the PIII treatment. During the thermal evolution of crystallographic phase analyses by ISS-XRD, after nitriding, structure evolution occurs mainly by nitrogen diffusion. In the nitrided samples prepared under the highest ion fluences—longer treatment times and frequencies (PIII 300 °C 6 h and PIII 400 °C 3 h) containing a significant amount of γ_N—a transition from the γ_N phase to the α and CrN phases and the formation of oxides occurred.

Keywords: UNS S44400 alloy; nitriding at low temperature; α_N phase; γ_N phase; in situ thermal evolution of crystallographic phases; synchrotron XRD

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MDPI and ACS Style

Schibicheski Kurelo, B.C.E.; Lepienski, C.M.; de Oliveira, W.R.; de Souza, G.B.; Serbena, F.C.; Cardoso, R.P.; das Neves, J.C.K.; Borges, P.C. Identification of Expanded Austenite in Nitrogen-Implanted Ferritic Steel through In Situ Synchrotron X-ray Diffraction Analyses. Metals 2023, 13, 1744. https://doi.org/10.3390/met13101744

AMA Style

Schibicheski Kurelo BCE, Lepienski CM, de Oliveira WR, de Souza GB, Serbena FC, Cardoso RP, das Neves JCK, Borges PC. Identification of Expanded Austenite in Nitrogen-Implanted Ferritic Steel through In Situ Synchrotron X-ray Diffraction Analyses. Metals. 2023; 13(10):1744. https://doi.org/10.3390/met13101744

Chicago/Turabian Style

Schibicheski Kurelo, Bruna C. E., Carlos M. Lepienski, Willian R. de Oliveira, Gelson B. de Souza, Francisco C. Serbena, Rodrigo P. Cardoso, Julio C. K. das Neves, and Paulo C. Borges. 2023. "Identification of Expanded Austenite in Nitrogen-Implanted Ferritic Steel through In Situ Synchrotron X-ray Diffraction Analyses" Metals 13, no. 10: 1744. https://doi.org/10.3390/met13101744

APA Style

Schibicheski Kurelo, B. C. E., Lepienski, C. M., de Oliveira, W. R., de Souza, G. B., Serbena, F. C., Cardoso, R. P., das Neves, J. C. K., & Borges, P. C. (2023). Identification of Expanded Austenite in Nitrogen-Implanted Ferritic Steel through In Situ Synchrotron X-ray Diffraction Analyses. Metals, 13(10), 1744. https://doi.org/10.3390/met13101744

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Identification of Expanded Austenite in Nitrogen-Implanted Ferritic Steel through In Situ Synchrotron X-ray Diffraction Analyses

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