Thermal Evolution of Expanded Phases Formed by PIII Nitriding in Super Duplex Steel Investigated by In Situ Synchrotron Radiation
Bruna Corina Emanuely Schibicheski Kurelo,
João Frederico Haas Leandro Monteiro,
Gelson Biscaia de Souza,
Francisco Carlos Serbena,
Carlos Maurício Lepienski,
Rodrigo Perito Cardoso,
Silvio Francisco Brunatto
Affiliations
Bruna Corina Emanuely Schibicheski Kurelo
Laboratory of Mechanical Properties and Surfaces, Department of Physics, State University of Ponta Grossa, Campus Uvaranas, Ponta Grossa 84030-000, Brazil
João Frederico Haas Leandro Monteiro
Interdisciplinary Center of Fluid Dynamics, Federal University of Rio de Janeiro, Rio de Janeiro 21941-594, Brazil
Gelson Biscaia de Souza
Laboratory of Mechanical Properties and Surfaces, Department of Physics, State University of Ponta Grossa, Campus Uvaranas, Ponta Grossa 84030-000, Brazil
Francisco Carlos Serbena
Laboratory of Mechanical Properties and Surfaces, Department of Physics, State University of Ponta Grossa, Campus Uvaranas, Ponta Grossa 84030-000, Brazil
Carlos Maurício Lepienski
Postgraduate Program in Mechanical and Materials Engineering, Federal Technological University of Paraná, Campus Ecoville, Curitiba 81280-340, Brazil
Rodrigo Perito Cardoso
LabMat, Department of Mechanical Engineering, Federal University of Santa Catarina, Campus Trindade, Florianópolis 88040-900, Brazil
Silvio Francisco Brunatto
Department of Mechanical Engineering, Federal University of Paraná, Curitiba 81531-980, Brazil
The Plasma Immersion Ion Implantation (PIII) nitriding was used to form a modified layer rich in expanded austenite (γN) and expanded ferrite (αN) phases in super duplex steel. The thermal stability of these phases was investigated through the in situ synchrotron X-ray diffraction. All the surfaces were analyzed by SEM, EDS, and nanoindentation. During the heating stage of the thermal treatments, the crystalline structure of the γN phase expanded thermally up to a temperature of 350 °C and, above this temperature, a reduction in the lattice parameter was observed due to the diffusion of nitrogen into the substrate. During the isothermal heating, the gradual diffusion of nitrogen continued and the lattice parameter of the γN phase decreased. Increasing the treatment temperature from 450 °C to 550 °C, a greater reduction in the lattice parameter of the γN phase occured and the peaks related to the CrN, α, and αN phases became more evident in the diffractograms. This phenomenon is associated with the decomposition of the γN phase into CrN + α + αN. After the heat treatments, the thickness of the modified layers increased and the hardness values close to the surface decreased, according to the diffusion of the nitrogen to the substrate.
