Influences of cryogenic CO₂ and LN₂ on surface integrity of inconel 625 during face milling

ABSTRACT

Inconel 625 is a nickel-based super alloy especially used in aeronautical industries, due to its high mechanical strength, exceptional weldability and good corrosion resistance properties. However, machinability of Inconel 625 is quite challenging because of high-level heat generation in the cutting zone. In this work, to improve sustainable machining of Inconel 625; cryogenic CO₂ and LN₂ have been used as lubricants. Face milling was performed at two feed rates (f) of 0.2 and 0.6 mm/rev and spindle speeds (n) of 509 and 764 rpm with cryogenic (CO₂ and LN₂) cooling environments. The resulting surface characteristics, such as morphology, topography, micro-hardness and residual stress, along with chip morphology and tool wear, were investigated. Both cryogenic lubricants offered relatively better results at lower feed rate (f) and spindle speed (n). While cryogenic CO₂ provided better surface morphology and topography, LN₂ provided lower residual stress and higher surface micro-hardness.

KEYWORDS:

• Face milling
• cryogenics
• surface integrity
• chip morphology
• tool wear