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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Effects of plasma nitriding with post-oxidation and of salt bath on the corrosion resistance of a tool steel

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Ranalli, G. A. ; Pallone, A. S. N. ; Pereira, V. F. ; Oliveira, R. G. ; Mariano, N. A. [5]
Total Authors: 5
Document type: Journal article
Source: MATERIA-RIO DE JANEIRO; v. 14, n. 2, p. 814-823, 2009.
Field of knowledge: Engineering - Materials and Metallurgical Engineering

Nitriding consists of a surface hardening treatment under a nitrogen atmosphere during a certain time and temperature that may be performed by a conventional procedure (liquid or gaseous) or using plasma. The material uses in the present work was a modified type AISI H10 toll stell that has been nitrided by plasma and salt bath procedures with the objective to produce a layer with high toughness and corrosion resistant. The microstructure of the nitrided layer was characterized by scanning electron microscopy and X-ray diffraction. The layer effective depth was determined by micro-hardness profiling and the corrosion resistance was evaluated by dynamic polarization tests in an aqueous solution of sodium chloride 0,5 mol L-1 and also by testing in a salty spray camera. The microstructure obtained after the previous heat treatment of quenching and tempering consisted of a tempered martensite matrix containing a homogeneous dispersion of spherodized carbides. The nitrided layer produced by the salt bath treatment presented a diffusion layer with a depth of 150µm and an embrittled compound layer with a thickness of about 10µm. The nitrided layer created by the plasma treatment with post-oxidation presented a homogeneous compound layer with thickness of up to 7µm and a diffusion layer with a network of nitride precipitates the surfaces that were plasma nitrided with post-oxidation presented a better resistance to corrosion in aqueous 0,5 mol L-1 NaCl solution. (AU)