Tool wear and chip formation during dry high speed turning of direct aged Inconel 718 aerospace superalloy using different ceramic tools

Abstract

Direct aged Inconel 718 superalloy is used in manufacturing critical cross-sections of aero-engine components. It is a hard-to-machine material, especially in dry conditions. To perform successful machining operations for this alloy, cutting tools with high hot hardness and chemical stability are required. The present study investigates the tool wear and chip formation during dry finish turning of direct aged Inconel 718 superalloy (51–53 HRC) using different ceramic tools. Pure alumina with added ZrO2 and alumina matrix reinforced with silicon carbide whiskers tools were used at cutting speeds of 150 and 250 m/min. A scanning electron microscope and energy dispersing spectroscopy were utilized to study the tool wear mechanisms. Structural and phase transformations during cutting on the tool–chip interface at the higher cutting speed were analyzed with X-ray photoelectron spectroscopy. Chip-undersides and cross-sections were studied with scanning electron microscope to investigate the chip formation mechanism. Results reveal that pure alumina with added ZrO2 can be an adequate choice for machining direct aged Inconel 718 because of its higher abrasive wear resistance and the formation of a sapphire protective tribo-layer at the tool–chip interface under severe cutting conditions. Chipping and notching of the cutting edge was found to decrease with the rise of the cutting speed for this tool material. As confirmed by X-ray photoelectron spectroscopy, alumina reinforced with silicon carbide whiskers tool was found to have a lower performance due the chemical degradation of the whiskers, especially at the higher cutting speed (250 m/min).

Wear Mechanisms and Notch Formation of Whisker-Reinforced Alumina and Sialon Ceramic Tools during High-Speed Turning of Inconel 718

“…This separation was largely considered as a tearing process, which favored interrupted seizure and consequent pullout of tool material. The effect of the adhered workpiece material on tool wear was also reported by Shalaby [ 15 ]. The Si-O tribo-film was found on the worn cutting edge, which indicated that the oxidation happened to the SiC whiskers.…”

Pareto Analysis of Machining Factors Significance When Turning of Nickel-Based Superalloy Inconel 718

“…The finished surface machined with the PCBN tool achieves a more consistent quality and better surface roughness during machining [15,23]. A significant disadvantage of this type of tool is its high cost, but it is lower than that of a CBN tool [32].…”

“…Silicon carbide (SiC) fibers or fibers are added to increase the strength of Al 2 O 3 ceramic tools and increase thermal conductivity because SiC has a very high tensile strength. Alumina ceramics (Al 2 O 3 + SiC whisker ), reinforced with filaments, can achieve cutting speeds ranging from 200 to 750 m/min and feed rates from 0.18 to 0.375 mm/rev and have increased strength [23,32]. R. P. Zeilmann et al [35] compared ceramic inserts with SiAlON and Al 2 O 3 + SiC whisker and investigated the cooling effect.…”

Optimization of Dry Turning of Inconel 601 Alloy Based on Surface Roughness, Tool Wear, and Material Removal Rate

“…Feed was the most influencing parameter for cutting force and surface roughness while cutting speed was the most influencing parameter for flank wear. Shalaby Veldhuis [24] investigated tool wear and chip formation with different ceramic tools. The results showed that alumina with added ZrO 2 had the best resistance to abrasive wear.…”