| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1659317 | Surface and Coatings Technology | 2010 | 5 Pages |
The present work investigates the influence of gas nitriding pressure on the modification of surface properties of ASTM F138 stainless steel. Nitrided surfaces were characterized by X-ray diffraction, Conversion Electron Mössbauer Spectroscopy, Scanning Electron Microscopy and Vickers microhardness. Plasma nitriding was carried out in a medium of 80% H2 and 20% N2, at 400 °C, for 4 h, pressures between 3 and 7 torr. A modified layer, whose depth ranging from 5.4 to 6.6 μm, was observed for all the nitrided samples, regardless of the nitriding pressure. The sample treated at 7 torr showed the best result of hardness.Besides γN phase, the hexagonal ε phase (Fe2 + xN) was also observed on the Mössbauer spectra up to 0.4 μm depth of the nitrided samples. X-ray diffraction spectra were analyzed by full profile fitting, using the triclinic structure for the γN phase. The results indicated that nitrogen concentration reaches a maximum for a pressure of 4 torr.
