Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/231595

Title

The effect of hydrogen on the growth of the nitrided layer in r.f.-plasma-nitrided austenitic stainless steel AISI 316

Author(s)

Kumar, S.;  Baldwin, M. J.;  Fewell, M. P.;  Haydon, S. C.;  Short, K. T.;  Collins, G. A.;  Tendys, J.

Abstract

Austenitic stainless steel AISI 316 has been nitrided by low-temperature r.f. plasmas containing various nitrogen-hydrogen gas mixtures, in order to study the effect of hydrogen on the growth of the 'expanded austenite' layer. The layers thus produced have been characterised using cross-sectional scanning electron microscopy, X-ray diffraction and instrumented microhardness measurements; the plasmas were studied by optical emission spectroscopy. The treated layer shows higher resistance to acid etching than the bulk material. Provided that the partial pressure of nitrogen is held constant, the addition of hydrogen at concentrations in the range 5-50% results in thicker nitrided layers and enhanced surface hardness compared with treatments in pure nitrogen. An excessive amount of hydrogen (~75%), on the other hand, retards the nitriding process. Optical spectroscopy indicates that the addition of hydrogen does not increase the concentration of active nitriding species, although mass spectroscopy shows the presence of NH1-4. The beneficial effect of hydrogen is therefore due to the action of hydrogen atoms and molecules at the surface of the workpiece.

Publication type

Journal article

Source

Surface and Coatings Technology, Vol. 123, no. 1 (Jan 2000), pp. 29-35

Publication year

2000

FOR Code(s)

0204 Condensed Matter Physics;  0306 Physical Chemistry (Incl. Structural);  0912 Materials Engineering

Keyword(s)

Addition reactions;  Austenite;  Composition effects;  Crosssectional scanning electron microscopy;  Emission spectroscopy;  Hydrogen;  Mass spectrometry;  Microhardness;  Optical emission spectroscopy;  Plasma nitriding;  Plasmas;  Protective coatings;  Stainless steel AISI 316;  Steel;  X ray diffraction analysis

Publisher

Elsevier

ISSN

0257-8972

Publisher URL

http://dx.doi.org/10.1016/S0257-8972(99)00393-X

Copyright

Copyright © 2000 Elsevier Science SA.

Additional information

Supported by the Australian Research Council and the Australian Institute of Nuclear Science and Engineering (AINSE).

Peer reviewed