Modification of EN9 Steel Surface by Salt Bath Nitrocarburizing Process

Nitrocarburizing is a thermochemical treatment which involves the diffusional addition of nitrogen and carbon to the surface of ferrous materials. Usually carried out at temperatures within the ferritic phase field of the Fe-N-C system, i.e. below 593 °C, the treatment improves the resistance to scuffing through the development of a compound layer at the surface consisting predominantly of epsilon carbonitride, Fe2.3(C,N). The treated components also exhibit enhanced fatigue properties on account of the diffusion zone where nitrogen is held in solid solution beneath the compound layer. Nitrocarburizing is therefore applied advantageously to textile machinery components, water pump parts, timing gears and a number of automotive parts which undergo sliding-rolling. The aim of the present research is to investigate the effects of salt bath nitrocarburizing on the EN 9 steel. An increase in wear resistance and impact strength has been found, whereas a very slight variation in microhardness has been reported. ARTICLE HISTORY Received 12-04-2017 Revised 09-05-2017 Accepted 15-05-2017 Published 29-06-2017