Table of Contents
Journal of Metallurgy
Volume 2017 (2017), Article ID 1052706, 7 pages
https://doi.org/10.1155/2017/1052706
Research Article

Nitriding Process Characterization of Cold Worked AISI 304 and 316 Austenitic Stainless Steels

1Nuclear and Energy Research Institute, IPEN, Avenida Lineu Prestes 2242, 05508-000 São Paulo, SP, Brazil
2MAHLE Metal Leve S/A, Rod. Anhanguera, s/n, Tijuco Preto, 13205-700 Jundiaí, SP, Brazil
3School of Engineering, Presbyterian Mackenzie University, Rua da Consolação 930, 01302-901 São Paulo, SP, Brazil

Correspondence should be addressed to Waldemar Alfredo Monteiro

Received 26 June 2016; Revised 9 September 2016; Accepted 18 September 2016; Published 18 January 2017

Academic Editor: Eric Jan Mittemeijer

Copyright © 2017 Waldemar Alfredo Monteiro et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The nitriding behavior of austenitic stainless steels (AISI 304 and 316) was studied by different cold work degree (0% (after heat treated), 10%, 20%, 30%, and 40%) before nitride processing. The microstructure, layer thickness, hardness, and chemical microcomposition were evaluated employing optical microscopy, Vickers hardness, and scanning electron microscopy techniques (WDS microanalysis). The initial cold work (previous plastic deformations) in both AISI 304 and 306 austenitic stainless steels does not show special influence in all applied nitriding kinetics (in layer thicknesses). The nitriding processes have formed two layers, one external layer formed by expanded austenite with high nitrogen content, followed by another thinner layer just below formed by expanded austenite with a high presence of carbon (back diffusion). An enhanced diffusion can be observed on AISI 304 steel comparing with AISI 316 steel (a nitrided layer thicker can be noticed in the AISI 304 steel). The mechanical strength of both steels after nitriding processes reveals significant hardness values, almost 1100 HV, on the nitrided layers.