Effect of Cutting Parameters and Cutting Environment on Surface Integrity During Machining of Nimonic C-263

Abstract

Nimonic C-263 has been widely used in hot portion of jet engine, submarine and chemical industries, gas turbine components, heat exchanger and ultra-supercritical power plant due to its ability to operate at elevated temperature for long period of time and higher resistance to corrosion and oxidation in acidic and aqueous environment. Properties such as high shear strength, low thermal conductivity, high tendency towards strain hardening, high hot hardness, and chemical affinity towards tool material poses greater challenge to the industries for achieving higher productivity and good surface quality of component with sustainable machining. Topographical, mechanical, metallurgical, chemical and thermal changes happen in the surface and sub-surface layer of material during machining which influences the functional performance of component. The study focuses on the effect of coating and cooling technique on surface integrity during machining of Nimonic C-263. Surface and sub-surface alteration such as surface damages, grain refinement, microstructural alteration, white layer and work-hardened layer during machining was examined using Field emission scanning electron microscopy (FESEM), X ray diffraction (XRD) system, XRD texture measurement and micro hardness tester. The effect of cutting speed and feed rate on surface integrity under these environments also has been analysed. The research demonstrated significant improvement in surface integrity with the use of minimum quantity lubrication (MQL) and flood environment during machining at low and medium cutting condition. High tool wear of uncoated tool and less cooling and lubricating efficiency of MQL and flood together deteriorate surface integrity at high cutting speed and feed. The PVD multilayer coated tool even under dry machining condition has given comparable result and sometimes even better than wet machining with uncoated tool. Surface damages in the form of micro cracks, voids, grooves, cavity and material transfer mainly observed in the surface. Deformed zones were intrinsic for all process conditions whereas their intensity and thickness increases with increases in tool wear and cutting parameter. The increase of feed rate had more influence on the plastic deformation. Overall it can be recommended that dry machining can be more beneficial than wet machining when PVD multilayer coated tool vii used under high cutting speed and feed. This is particularly important for higher productivity in sustainable manner.