The effect of the white layer on micro-pitting and surface contact fatigue failure of nitrided gears

Abstract

The effect of the ‘white layer’ in nitrided steel on micro-pitting of gears has been investigated by comparing the performance of case carburized and nitrided gears fabricated from modern, low-oxygen steels. It is shown that the white layer, produced during nitriding, imparts a high resistance to micro-pitting. Because surface contact fatigue is nucleated at micro-pits in low-oxygen steels, the resistance to micro-pitting also manifests itself in a higher fatigue resistance for the nitrided material.