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Gas nitriding is emerging as the significant surface hardening process for today's and future industry, constituting a viable alternative to the well-established carburising process. Most gears, shafts, hubs, pins and other parts are carburised in mass production to various case depths with accurate carbon potantial control. On the other hand nitriding brings along several advantages.
In a predominant number of gas-nitriding installations worldwide, even including latest systems, the controlled parameter
is simply the atmosphere flow rate and the resultant dissociation rate. This approach is inadequate, since neither of these
parameters, by itself, directly influences the properties of the nitrided layer. Although recognized for many years, the
nitriding potential has only recently been harnessed technologically to control nitriding.
Properties of the white layer (e.g. hardness, brittleness, load-bearing capacity, etc.) can be directly linked to nitrogen
concentration in the surface of the treated part, such concentration being directly dependent on the nitriding potential.
The type of phase formed under isothermal conditions will depend directly on the concentration of nitrogen.
An industrial-scale, computer controlled and fully automated gas nitriding system, with nitriding potential control,
has been developed by Nitrex Metal Inc. in Canada and successfully implemented industrially as the
NITREG process.
CARBURISING vs. NITRIDING
TECHNICAL LAYOUT OF NITREX GAS NITRIDING SYSTEM
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