Free Access
Microsc. Microanal. Microstruct.
Volume 8, Number 4-5, August / October 1997
Page(s) 335 - 352
Microsc. Microanal. Microstruct. 8, 335-352 (1997)
DOI: 10.1051/mmm:1997126

Complete TEM Investigation of a Nitrided Layer for a Cr Alloy Steel

Jean-Noël Locquet1, Richard Soto2, Laurent Barrallier1 et Ahmed Charaï2

1  Laboratoire MécaSurf, 2 Cours des Arts et Métiers, 13617 Aix-en-Provence Cedex 1, France
2  EDIFIS, Laboratoire de Métallurgie, Faculté de Saint Jérôme, 13397 Marseille Cedex 20, France

Un-nitrided material is investigated by TEM in order to identify the different types of precipitates and to determine their respective volume fraction. M23C6 and M4C3 carbides are reported. Experimental results are confirmed by thermodynamical calculations. The same material is nitrided in industrial conditions and also investigated by TEM. Crystallographic structures and chemical compositions are determined by Selected Area Electron Diffraction (SAED), Energy Dispersive Spectroscopy (EDS) and Electron Energy Loss Spectroscopy (EELS). V-rich carbonitrides, incoherent globular CrN nitrides and semi-coherent CrN nitrides are reported. In both cases, CrN precipitates have the Baker-Nutting orientation relationship with respect to the ferritic matrix. Their size distributions as a function of depth are studied.

8140E - Cold working, work hardening: post deformation annealing, recovery and recrystallisation: textures.
6116D - Electron microscopy determinations of structures.
6475 - Solubility, segregation, and mixing.
8130M - Precipitation.
7920K - Other electron surface impact phenomena.

Key words
alloy steel -- electron diffraction -- electron energy loss spectra -- precipitation -- surface hardening -- transmission electron microscopy -- TEM -- nitrided layer -- Cr alloy steel -- precipitates -- volume fraction -- carbides -- thermodynamical calculations -- crystallographic structures -- chemical compositions -- selected area electron diffraction -- energy dispersive spectroscopy -- electron energy loss spectroscopy -- EELS -- V rich carbonitrides -- incoherent globular CrN nitrides -- semi coherent CrN nitrides -- Baker Nutting orientation relationship -- ferritic matrix -- size distributions

© EDP Sciences 1997