Influência do fluxo intermitente de nitrogênio na formação da camada nitretada do aço inoxidável ISO 5832-1

Abstract

ABNT ISO 5832-1 steel is an austenitic steel that is used for applications with high risks of corrosion, but its low carbon content makes it unsuitable for applications where hardness is necessary. As a surface hardening strategy for steels of this nature, this work deals with plasma nitriding by pulsed flow of nitrogen, which appears as an alternative to low temperature treatment, with the purpose of maintaining the inherent characteristic of corrosion protection, through diffusion. Of interstitial nitrogen atoms. This process follows a methodology of periods of nitrogen supply followed by periods of non-supply according to the logic: 120/120, 48/192, 24/216 and 12/228, with these parameters being measured in seconds, in addition to continuous nitriding in order to establish comparison. All nitridations took a total of 2h. The results obtained for the thickness of the nitrided layer are in accordance with the literature and decrease with the nitrogen supply time. In the same vein, the nitrogen concentration in the nitrided layer showed a drop along with the nitrogen supply time, but in a smaller order than that seen in work with longer pulse periods. Surface hardness showed a similar trend for all tested conditions. Thus, it appears that the pulsed flow of nitrogen in smaller pulses promotes nitrided layers with higher nitrogen content compared to longer pulse periods. Thus, the use of intermittent nitrogen flow to control the nitrided layer proves to be beneficial, since changing this parameter produces different results.