Investigation on Surface Integrity in Milling of Inconel X750: A Comprehensive analysis of Cutting Edges and Machining Parameters

Abstract

For over a century, machining has been a crucial manufacturing method, with milling standing out as a versatile and effective process for various engineering materials. Ni-based superalloys, renowned for their exceptional properties, present challenges in machining, causing excessive tool wear and surface quality issues. Techniques such as heat treatments, environmental adjustments, and tool geometry alterations are employed to mitigate tool wear and affect surface integrity, crucial for determining the quality of machined work materials, especially in high-strength superalloys where shear deformation induces grain misorientation. In this research article, an experimental study was carried out to find the impact of the different cutting edges on surface integrity while milling Inconel X750. Response Surface Methodology was employed using a central composite rotatable design of experiments to investigate the surface roughness of the machined sample under various cutting conditions. A thorough analysis was undertaken to explore the surface integrity of Inconel X750, involving variations in milling machining parameters (i.e., low, mid, and high) and the utilization of diverse cutting tool inserts. The investigation centred on analysing the sub-surface microstructure, texture, and residual stresses of the machined surface, aiming to achieve a comprehensive understanding of the material's surface characteristics. The double-coated cutting tool T2, with a diameter of 0.8 mm, exhibited superior performance in surface quality and grain distribution, particularly at low cutting parameters (feed rate: 0.15 mm/rev, cutting speed: 35 mm/min, depth of cut: 0.1 mm), showing fine equiaxed and lognormal grain distribution alongside low residual stresses (−36.8 MPa compressive, maximum shear residual stresses: 7.2 MPa) and a surface roughness of 0.17 μm.