A Comprehensive Review on the Conventional and Non-Conventional Machining and Tool-Wear Mechanisms of INCONEL®

Abstract

Nickel-based superalloys, namely INCONEL® variants, have had an increase in applications throughout various industries like aeronautics, automotive and energy power plants. These superalloys can withstand high-temperature applications without suffering from creep, making them extremely appealing and suitable for manufactured goods such as jet engines or steam turbines. Nevertheless, INCONEL® alloys are considered difficult-to-cut materials, not only due to their superior material properties but also because of their poor thermal conductivity (k) and severe work hardening, which may lead to premature tool wear (TW) and poor final product finishing. In this regard, it is of paramount importance to optimise the machining parameters, to strengthen the process performance outcomes concerning the quality and cost of the product. The present review aims to systematically summarize and analyse the progress taken within the field of INCONEL® machining sensitively over the past five years, with some exceptions, and present the most recent solutions found in the industry, as well as the prospects from researchers. To accomplish this article, ScienceDirect, Springer, Taylor & Francis, Wiley and ASME have been used as sources of information as a result of great fidelity knowledge. Books from Woodhead Publishing Series, CRC Press and Academic Press have been also used. The main keywords used in searching information were: “Nickel-based superalloys”, “INCONEL® 718”, “INCONEL® 625” “INCONEL® Machining processes” and “Tool-wear mechanisms”. The combined use of these keywords was crucial to filter the huge information currently available about the evolution of INCONEL® machining technologies. As a main contribution to this work, three SWOT analyses are provided on information that is dispersed in several articles. It was found that significant progress in the traditional cutting tool technologies has been made, nonetheless, the machining of INCONEL® 718 and 625 is still considered a great challenge due to the intrinsic characteristics of those Ni-based-superalloys, whose machining promotes high-wear to the tools and coatings used.

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

“…High-accuracy machining of any hard-to-cut metal is the most substantial advantage of non-conventional processes, regardless of the shape complexity, while not requiring contact between the tool and the wrought stock. For further information about INCONEL ® 718 and 625 alloys and all surrounding subjects, such as microstructure, machining problems and predictive mathematical models, we suggest Pedroso et al [ 43 ] for better comprehension.…”

The effect of chipbreaker parameters on the cutting temperature of Inconel 718 alloy based on the secondary development of Abaqus

“…With high strength, high creep resistance and high fatigue life, Inconel 718 alloy is used extensively in nuclear engineering, aviation and space, cryogenic engineering and turbines [1,2] . However, Inconel 718 has poor thermal conductivity and high cutting temperature, which tend to exacerbate the plastic deformation of chips and are typically difficult to machine metals [3] .…”

Effect of microstructure on low cycle fatigue behavior of Inconel 706 at 650°C

“…While IN718 has excellent mechanical and corrosion properties at room and elevated temperature up to 650 C, [1][2][3][4] conventional machining techniques of utilizing high-strength tools may not be applicable due to its extremely tough nature and low machinability. [5][6][7] IN706 has been developed to have improved fabricability, particularly machining, with similar mechanical properties to those of IN718. [8][9][10] Since the *Inconel alloy family was first developed in 1932, and its trademarks were registered by the International Nickel Company (INCO) in the United States.…”

“…Precipitation‐hardenable INCONEL nickel‐iron‐chromium alloy 706 (IN706) has been developed by INCO in the 1970s, based on the chemistry of Inconel 718 (IN718) that is a workhorse of Ni (nickel)‐based superalloy industry. While IN718 has excellent mechanical and corrosion properties at room and elevated temperature up to 650°C, 1–4 conventional machining techniques of utilizing high‐strength tools may not be applicable due to its extremely tough nature and low machinability 5–7 . IN706 has been developed to have improved fabricability, particularly machining, with similar mechanical properties to those of IN718 8–10 .…”