Pulsed plasma nitriding of large components and coupons of chrome plated SS316LN stainless steel

Pulsed plasma nitriding of electroplated Cr on stainless steel substrates is reported. The properties of the chromium nitride coatings on small coupons synthesised simultaneously with large-scale components have been investigated. The effect of temperature and duration of the nitriding process on the coating properties are discussed. A gradual variation in the hardness profile from a peak harness of about 950 HV at the surface to about 650 HV at 90 lm of case depth has been achieved. The chromium nitride coating was not brittle. The resistance of the coating to abrasive wear was higher than that for Cr. X-ray diffraction and energy dispersive X-ray analysis confirmed that the coating is composed of polycrystalline Cr2N and Cr indicating that there was partial conversion of the electroplated Cr film to nitride.