Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
PLASMA NITRIDING OF SINTERED AUSTENITIC STAINLESS STEEL 316L WITH NITROGEN PULSED FLOW
Submission Author:
Diandra Grossmann Pereira , PR
Co-Authors:
Diandra Grossmann Pereira, Marcio Mafra, euclides alexandre bernardelli, Cristiano Binder
Presenter: Diandra Grossmann Pereira
doi://10.26678/ABCM.COBEM2021.COB2021-1174
Abstract
Surface treatments are used in sintered stainless steel with the aim of increasing the hardness of the surface and its wear and corrosion resistance. Previous studies have shown the formation of cracks in layers formed in nitrided samples under some treatment conditions. A promising way to avoid crack formation, that is the aim of this work, is to vary the nitrogen potential, which is achieved by pulsing the nitrogen flow, during plasma nitriding. To reach the objective, samples of sintered stainless steel 316L were plasma nitrided for 4 h e 8 h, with continuous and pulsed nitrogen flows (cycles of 20 minutes, being 2 minutes with nitrogen on and 18 minutes with nitrogen off). After the nitriding, the samples were characterized by scanning electron microscopy, X-ray diffraction and microhardness. In all processing conditions was observed the formation of expanded austenite in the nitrided layers. The sample treated for 8 h in continuous flow, was the only presenting formation of chromium nitrides. The samples nitrided in pulsed flow have shown lower hardness in comparison to the continuous flow, for similar processing times. The sample treated for 8 h with continuous flow showed the highest hardness of all samples. SEM results indicated the lowest occurrence of cracks on the samples nitrided under pulsed flow when compared with the continuous treatment. This behavior is related to the reduction of nitrogen content in the layer, and the consequent reduction of the residual stresses from the formation of expanded austenite.
Keywords
plasma nitriding, sintered stainless steel, pulsed nitrogen flow
