Investigations on the Surface Integrity and Wear Mechanisms of TiAlYN-Coated Tools in Inconel 718 Milling Operations

Abstract

Inconel 718 is a Ni superalloy with superior mechanical properties, even at high temperatures. However, due to its high hardness and low thermal conductivity, it is considered a difficult-to-machine material. This material is widely used in applications that require good dimensional stability, making the milling process the most used in machining this alloy. The wear resulting from this process and the quality of the machined surface are still challenging factors when it comes to Inconel 718. TiAlN-based coating has been used on cutting tools with Yttrium as a doping element to improve the process performance. Based on this, this work evaluated the machined surface integrity and wear resistance of cutting tools coated using Physical Vapor Deposition (PVD) HiPIMS with TiAlYN in the end milling of Inconel 718, varying the process parameters such as cutting speed (vc), feed per tooth (fz), and cutting length (Lcut). It was verified that the Lcut is the parameter that exerts the most significant influence since, even at small distances, Inconel 718 already generates high tool wear (TW). Furthermore, the main wear mechanisms were abrasive and adhesive wear, with the development of a built-up edge (BUE) under a125 m/min feed rate (f) and a Lcut = 15 m. Chipping, cracking, and delamination of the coating were also observed, indicating a lack of adhesion between the coating and the substrate, suggesting the need for a good interlayer or the adjustment of the PVD parameters.

INCONEL® Alloy Machining and Tool Wear Finite Element Analysis Assessment: An Extended Review

“…These tools were employed in finishing operations on INCONEL ® 718 to advance the comprehension of the wear patterns exhibited by coated tools during the machining of these alloys. Silva et al [70] evaluated machined surfaces' integrity and TW resistance using cutting tools coated through PVD HiPIMS with TiAlYN during the end milling of INCONEL ® 718. These efforts demonstrate that experimental work is time-consuming and simulation can save resources and time for researchers.…”

A Comparative Study of Different Milling Strategies on Productivity, Tool Wear, Surface Roughness, and Vibration

“…Figure 7c shows the EDS analysis, which shows that the chemical composition of the tool surface in sample areas Z1 and Z2 is mainly composed of the W element, and in sample area Z3, the Al element can be observed from the milled surface. Regarding the good performance of the coating, recent work carried out by the same group [44][45][46] has identified problems with the adhesion of some coatings (TiAlTaN, TiAlYN and TiAlTaN, TiAlYN) deposited using industrial machines on the same substrate, but machining other materials (Inconel and AMPCO alloy), a situation that was not observed in the case of these tools working according to this cutting strategy and machining an aeronautical aluminum alloy (AA7075-T7451). Thus, these coatings demonstrate good adhesion properties to the substrate and prove to be efficient in terms of hindering the adhesion of the machined material to the tool surface.…”

An In-Depth Exploration of Unconventional Machining Techniques for INCONEL® Alloys

“…The commercial WC TiAlN-coated tool [ 32 , 33 ] used in the experiments suffered mainly from erosion on the cutting edge due to diffusion wear after the abrasive wear when cutting INCONEL ® 713C. This type of coating, TiAlN, and its variants TiN [ 34 ], TiAlYN [ 35 ] and TiAlVN, have been experimented with in INCONEL ® 718. Osmond et al [ 36 ] described the mechanisms involved in chip formation and wear for SiAlON-based ceramics and silicon carbide whisker-reinforced alumina (WRA, Figure 4 ) round inserts during the turning process of solution-annealed INCONEL ® 718, utilizing a cutting fluid with an oil-concentration of 10%.…”