Surface damages and tool wear mode in end milling of hastelloy-C276 under dry and wet conditions

Hastelloy-C276 is a nickel based superalloy that is widely used in chemical, petro-chemical, environmental and nuclear industries due to its outstanding performance in a wide range of corrosive mediums. The superior properties of nickel based superalloys impair their machinability which increases the difficulty in obtaining a good surface finish. Because most of the components' failures are initiated from surface defects, several researchers have been concerned about surface integrity in machining aerospace superalloys particularly Inconel-718. Due to the lack of studies done on machining corrosion-resistant superalloys, this study aims to investigate surface damages and tool wear modes in milling Hastelloy-C276 under dry and wet conditions. The absence of cooling and lubricating actions in dry machining resulted in the formation of craters, severe plastic deformation, voids, debris re-deposition and materials drag. The breakage of the nucleated carbide phases resulted in the formation of nucleated cavities on the machined surface in both wet and dry machining. Adhesive tool wear was less in dry machining due to the formation of oxide layers on tool faces which suppressed the formation of built-up edges due to the weak adhesion properties of oxide compounds which resulted in less surface roughness at v_c = 50 m/min. On the other hand, the higher temperature and friction in dry machining resulted in severer tool coating delamination.