Abstract

RODRIGUEZ VALDIVIA, Marcelo  and  MOLLEHUANCA CABALLERO, Edgard. Caracterización mecánica y microestructural de un acero inoxidable Aisi:304 endurecido mediante nitruración usando residuos de melamina. Rev. Bol. Quim [online]. 2021, vol.38, n.5, pp.1-12. ISSN 0250-5460.  https://doi.org/10.34098/2078-3949.38.5.1.

This article presents the results obtained from the nitriding of an AISI: 304 stainless steel, subjected to a solid nitriding process recycling melanin residues; due to its chemical composition it constitutes a suitable material for supplying nitrogen gases. The micrographs showed that the nitriding process causes important structural changes with the formation of Fe nitrides (γ´-Fe4N and ɛ-Fe2N), which substantially increase the surface hardness. Tests at 550°C/4 hours, 580ºC /4 hours and 565ºC /3 hours, showed surface hardness of 30.17, 30.0 and 29.9 HRc; representing an increase of 67% when compared to steel in supply condition. Statistical analysis applying a factorial experimental design indicated that the main factors that influence hardness are: nitriding time and its interaction with temperature with a significance of 0.0094 and 0.0707 for a confidence level of 90%. The thickness of the hardened layer is directly dependent on the concentration and diffusion rate of N atoms that enter the steel from its surface and move towards the interior.

Keywords : Melamine; diffusion; nitriding; factorial experimental design; stainless steel AISI:304; surface hardness.

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