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Abstract
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Corrosion resistance of AISI M2 high speed steel samples plasma nitrided in different process gas
composition was studied using polarization test. In order to evaluate inherent properties of diffusion zone, the
white layer, i.e. compound layer, was removed. Phase structure and surface hardness of samples were charac
terized using XRay diffraction and microhardness tests. Evaluations of polarization curves indicated that
plasma nitriding in a gas flow rate of 25 sccm N2– 75 sccm H2 improves corrosion resistance of AISI M2 high
speed steel, while increasing nitrogen content in gas composition degrades corrosion properties. Metallo
graphic images of corroded surfaces revealed sever pitting corrosion by increasing nitrogen content in the pro
cess gas.
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