Plasma nitriding has been successfully employed to engineer the surfaces of austenitic stainless steels to improve their wear and triboogical properies.However,due to the precipitation of chromium nitrides in the nitrided case,conventional plasma nitriding suually resultis in the deterioration of corrosion resistance,which is unacceptable in man y application situatoiosn involving severe corrosive attack by the environment.Attempts have thus been made in recent years to improve the corrosion behaviour of plasma nitrided austenitic stainless stteels so as to achieve combined wear and corrosion resistant surfacs.Two applroaches have beeh examined.i.e. conventional high temperatuer nitriding followed by surface passivation treatments and low temperatue nitriding.The former produces a relatively thick and wear resistant nitrided subsurface and a corrosion resistant passivasion film on top of the surface.Whilst teh low temperature techniqe produces a thin,hard and precipitation-free nitrided layer,which possesses excellent corrosion properties.The present paper presents recent experimental results obtained and discusses the response of austenitic stainless steels to various treatments in terms of microstructures,kinetics,wear resistance and ocrrosion characteristics.
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