Prediction of hardness–depth profile from indentations at surface of materials

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Role of plastic deformation on the efficiency of a nitriding treatment: modelling of the hardness-depth profile

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Austenite modification of AISI 316L SS by pulsed nitrogen ion beams generated in dense plasma focus discharges

International audienceWe present the results of a surface modification of AISI 316L stainless steel by surface irradiation with high energy, pulsed nitrogen ion beams generated with 0.8 kJ dense plasma focus. The surface characterization was done using GAXRD, Auger electrons spectroscopy, TEM and optical microscopy. After the irradiation, we found a modification of a 1 μm thick surface layer, on which a gradual lattice expansion of the austenite with the number of irradiation pulses, i.e. with the total nitrogen ion fluence, was observed. In addition, ~ 40 nm close to the surface layer, a disordered lattice structure had been observed through TEM analysis. Those results can be explained in terms of the extreme thermal effect induced on the surface through the fast high energy release during the pulsed ion interaction with the steel surface, followed by an also rapid cooling down process which limits the nitrogen diffusion to the bulk

Austenite modification of AISI 316L SS by pulsed nitrogen ion beams generated in dense plasma focus discharges

We present the results of a surface modification of AISI 316L stainless steel by surface irradiation with high energy, pulsed nitrogen ion beams generated with 0.8 kJ dense plasma focus. The surface characterization was done using GAXRD, Auger electrons spectroscopy, TEM and optical microscopy. After the irradiation, we found a modification of a I pm thick surface layer, on which a gradual lattice expansion of the austenite with the number of irradiation pulses, i.e. with the total nitrogen ion fluence, was observed. In addition, similar to 40 nm close to the surface layer, a disordered lattice structure had been observed through TEM analysis. Those results can be explained in terms of the extreme thermal effect induced on the surface through the fast high energy release during the pulsed ion interaction with the steel surface, followed by an also rapid cooling down process which limits the nitrogen diffusion to the bulk. (c) 2009 Elsevier B.V. All rights reserved

Characterization of expanded austenite developed on AISI 316L stainless steel by plasma carburization

Expanded austenite generation through ion carburizing of AISI 316L using two different reactive gas mixtures (Ar 50%, H(2) 45%, CH(4) 5% and Ar 80%, H(2) 15%, CH(4) 5%) has been studied. It was found that an similar to 14 mu m surface layer of expanded austenite was developed with 30 min processing for both gas mixtures. Nevertheless, AES analyses have shown that on the similar to 150 nm surface layer carbon in a concentration of similar to 12% was diffused and located as carbide. For longer periods of processing, while for the gas mixture with 50% of Ar no significant modifications within those 150 nm surface layer were produced, for the gas mixture with 80% of Ar a gradual increase in the carbon concentration with time was found, with the extra carbon remaining as free carbon. The difference between both situations can be attributed to the different resulting current densities that have been of 7.0 rnA cm(-2) and 8.1 mA cm(-2) for 50% and 80% of Ar respectively. Higher current densities result in higher carbon and Ar ions fluxes inducing, from one side surface element concentration modification through sputtering, and from the other the enhancement of carbon diffusion on the first hundred nanometers of the surface layers. This free carbon on top of the surface layers can act as solid lubricant reducing wear rate. Nevertheless, and in spite of the fact that expanded austenite was proved to be corrosion resistant, a reduction against NaCl solution corrosion in relation to the base material was observed. This lost to corrosion resistance can be attributed to carbide development on the layers closer to the surface that can work as a trigger for localized corrosion. (C) 2010 Elsevier B.V. All rights reserved

Characterization of expanded austenite developed on AISI 316L stainless steel by plasma carburization

Expanded austenite generation through ion carburizing of AISI 316L using two different reactive gas mixtures (Ar 50%, H2 45%, CH4 5% and Ar 80%, H2 15%, CH4 5%) has been studied. It was found that an 14 µm surface layer of expanded austenite was developed with 30 min processing for both gas mixtures. Nevertheless, AES analyses have shown that on the 150 nm surface layer carbon in a concentration of 12% was diffused and located as carbide. For longer periods of processing, while for the gas mixture with 50% of Ar no significant modifications within those 150 nm surface layer were produced, for the gas mixture with 80% of Ar a gradual increase in the carbon concentration with time was found, with the extra carbon remaining as free carbon. The difference between both situations can be attributed to the different resulting current densities that have been of 7.0 mA cm−2 and 8.1 mA cm−2 for 50% and 80% of Ar respectively. Higher current densities result in higher carbon and Ar ions fluxes inducing, from one side surface element concentration modification through sputtering, and from the other the enhancement of carbon diffusion on the first hundred nanometers of the surface layers. This free carbon on top of the surface layers can act as solid lubricant reducing wear rate. Nevertheless, and in spite of the fact that expanded austenite was proved to be corrosion resistant, a reduction against NaCl solution corrosion in relation to the base material was observed. This lost to corrosion resistance can be attributed to carbide development on the layers closer to the surface that can work as a trigger for localized corrosion.Fil: García Molleja, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Nosei, L.. Universidad Nacional de Rosario; ArgentinaFil: Ferron, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); ArgentinaFil: Bemporad, E.. Universita Di Roma; ItaliaFil: Lesage, J.. Université Des Sciences Et Des Technologies de Lille;Fil: Chicot D.. Université Des Sciences Et Des Technologies de Lille; FranciaFil: Feugeas, Jorge Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentin

Modeling of very thin aluminum nitride film mechanical properties from nanoindentation measurements

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