The impact of the cutting parameters and tool condition on surface integrity when milling Inconel 625

Abstract

During machining, the workpiece material tends to undergo mechanical and thermal transformations. Machining Inconel 625 is a challenging task since this material has low thermal conductivity, rapidly work hardening, and maintains its strength even at high temperatures. This superalloy is used extensively by the aerospace and oil and gas industries due to both its corrosion and heat resistance. All these characteristics influence tool life, cutting forces, and the integrity of the machined surface, which, in turn, significantly impacts the fatigue life of the components. It is therefore important to understand the surface integrity induced during milling. Although many reports have been published about tool wear and surface integrity studies for Inconel alloys, especially on the effect of the tool condition on the surface and subsurface which address residual stress, corrosion, and deformed layers have not been investigated so far. This study highlights the importance of assessing the surface integrity of Inconel 625 clad workpieces milled with both fresh and worn tools at different cutting speeds and feed rates. The results show that the best conditions for maintaining surface integrity among the conditions tested are vc = 55 m/min and fz = 0.10 mm/tooth. The workpiece milled with a fresh tool presented better corrosion resistance, whereas the worn tool produced more compressive stress, indicating that such conditions would improve the fatigue life of the part.

Keywords

• Inconel 625
• Surface integrity
• Tool wear
• Corrosion resistance
• Residual stress