Metallurgical response of an AISI 4140 steel to different plasma nitriding gas mixtures
AUTOR(ES)
Skonieski, Adão Felipe Oliveira, Santos, Giovanni Rocha dos, Hirsch, Thomas Karl, Rocha, Alexandre da Silva
FONTE
Mat. Res.
DATA DE PUBLICAÇÃO
21/05/2013
RESUMO
Plasma nitriding is a surface modification process that uses glow discharge to diffuse nitrogen atoms into the metallic matrix of different materials. Among the many possible parameters of the process, the gas mixture composition plays an important role, as it impacts directly the formed layer's microstructure. In this work an AISI 4140 steel was plasma nitrided under five different gas compositions. The plasma nitriding samples were characterized using optical and scanning electron microscopy, microhardness test, X-ray diffraction and GDOES. The results showed that there are significant microstructural and morphological differences on the formed layers depending on the quantity of nitrogen and methane added to the plasma nitriding atmosphere. Thicknesses of 10, 5 and 2.5 µm were obtained when the nitrogen content of the gas mixtures were varied. The possibility to obtain a compound layer formed mainly by γ'-Fe4N nitrides was also shown. For all studied plasma nitriding conditions, the presence of a compound layer was recognized as being the responsible to hinder the decarburization on the steel surface. The highest value of surface hardness - 1277HV - were measured in the sample which were nitrided with 3vol.% of CH4.
Documentos Relacionados
- Influência da mistura gasosa nos processos de nitretação e nitrocarbonetação a plasma do aço AISI 4140
- Nitriding of AISI 1020 steel: comparison between conventional nitriding and nitriding with cathodic cage
- Propriedades do aço AISI 4140 nitretado a gás
- Surface Integrity Analysis in Machining of Hardened AISI 4140 Steel
- AISI 1005 Steel Plasma Treated by Different Thermochemical Surface Treatments