Enhanced surface properties of M2 steel by plasma nitriding pre-treatment and magnetron sputtered TiN coating

Abstract

AISI M2 high-speed steels are widely used in cutting/forming tools due to their easy machinability and balanced toughness. Unfortunately, they exhibit severe cutting edge wear, which reduces their useful lifetime. The lifetime of such steels can be improved by titanium nitride hard coating. However, in sliding wear applications having a metal-to-metal contact, such coatings exhibit low adhesion to the substrate due to substantial hardness differences among coating and substrate. Here, plasma nitriding is performed before the deposition of magnetron sputtered-TiN coating using various nitriding parameters to find whether the surface properties of the duplex treated sample can be altered by changing these parameters or not. It is found that the surface hardness and hardening depth can be improved by using the duplex treatment as compared to only TiN coating. A significant decrease in wear rate is attained using the duplex treatment and substantial improvement by altering the plasma nitriding parameters.