Previous heat treatment inducing different plasma nitriding behaviors in martensitic stainless steels
- Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, New South Wales 2234, Australia and Instituto de Fisica 'Gleb Wataghin', Unicamp, Campinas, Sao Paulo 13083-970 (Brazil)
In this work we report a study of the induced changes in structure and corrosion behavior of martensitic stainless steels nitrided by plasma immersion ion implantation (PI{sup 3}) at different previous heat treatments. The samples were characterized by x-ray diffraction and glancing angle x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, and potentiodynamic measurements. Depending on the proportion of retained austenite in the unimplanted material, different phase transformations are obtained at lower and intermediate temperatures of nitrogen implantation. At higher temperatures, the great mobility of the chromium yields CrN segregations like spots in random distribution, and the {alpha}{sup '}-martensite is degraded to{alpha}-Fe (ferrite). The nitrided layer thickness follows a fairly linear relationship with the temperature and a parabolic law with the process time. The corrosion resistance depends strongly on chromium segregation from the martensitic matrix, as a result of the formation of CrN during the nitrogen implantation process and the formation of Cr{sub x}C during the heat treatment process. Briefly speaking, the best results are obtained using low tempering temperature and low implantation temperature (below 375 deg. ) due to the increment of the corrosion resistance and nitrogen dissolution in the structure with not too high diffusion depths (about 5-10 {mu}m)
- OSTI ID:
- 20853528
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 24, Issue 5; Other Information: DOI: 10.1116/1.2219759; (c) 2006 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AUSTENITE
AUSTENITIC STEELS
CHROMIUM
CHROMIUM NITRIDES
CORROSION
CORROSION RESISTANCE
FERRITE
ION IMPLANTATION
MARTENSITE
MARTENSITIC STEELS
NITROGEN
PHASE TRANSFORMATIONS
PLASMA
SCANNING ELECTRON MICROSCOPY
SEGREGATION
STAINLESS STEELS
X RADIATION
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY