Effect of WC/C PVD coating on fatigue behaviour of case carburized SAE8620 steel

Case carburizing steels, such as SAE8620, are generally employed in manufacture of automotive components viz. gears and shafts. These components are often subjected to a combination of wear and fatigue loads. Though a number of coatings are available that can enhance performance under such loadings, but high processing temperatures forbid their application to heat-treated components. On the other hand, the low processing temperature for the WC/C coating permits its application to heat-treated parts. The coating exhibits favourable tribological properties, but its influence on fatigue behaviour is yet unexplored. The present work is aimed at investigating the influence of WC/C coating on the fatigue behaviour of case carburized SAE8620 steel, wherein performance of uncoated and coated specimens is compared by subjecting them to four point rotating bending fatigue tests. The results point out that the coating leads to 7% gain in endurance limit without considerably affecting the hardness and tensile strength.