Special Issue "Advancements in Machining Technologies of Titanium-Based Alloys"

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metal Casting, Forming and Heat Treatment".

Deadline for manuscript submissions: 31 March 2023 | Viewed by 4062

Special Issue Editor

School of Engineering and Built Environment, Griffith University, Gold Coast, QLD 4222, Australia
Interests: advanced manufacturing; high-speed machining of metals; metals, alloys and composites; laser materials processing; additive manufacturing (3D printing)

Special Issue Information

Dear Colleagues,

Machining has been and is still a major hurdle of manufacturing of titanium-based alloy components because of the low allowable cutting speed and high tooling cost. This is mainly attributed to the rapid increase in cutting temperature with an increase in cutting speed.

After being intensively investigated in decades, the significant progresses have been made to improve the machinability of titanium-based alloys in terms of the longer tool life and higher cutting speed.

The aim of this special issue in Metals is to present the state-of-the-art research status in the advancements of machining technologies of titanium-based alloys including, but not limited to, the following topics:

  • The machinability of various titanium alloys: additively manufactured titanium alloys, alpha-beta titanium alloys, beta titanium alloys etc.;
  • Assisted machining: thermally assisted, ultrasonic vibration assisted machining, etc.;
  • Non-traditional machining: electrical discharge machining, abrasive jet machining, etc.;
  • Effective cooling strategies: high pressure coolant, cryogenic machining, minimum quantity cooling etc.;
  • New materials, coatings and designs for cutting tools: polycrystalline diamond (PCD) tool, self-propelled rotary tool, etc.;
  • Tribology of cutting and tool wear;
  • Chip formation and control;
  • Computational simulation of machining of titanium alloys.

Prof. Dr. Shoujin Sun
Guest Editor

Manuscript Submission Information

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Keywords

  • high-speed machining
  • assisted machining
  • titanium alloys and composites
  • cutting tool technologies
  • cooling strategies
  • chip control
  • optimization
  • simulation
  • machined surface integrity

Published Papers (4 papers)

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Research

Article
Effect of Titanium Based Alloys on Thermo-Mechanical Behavior in 3D Forging Simulation
Metals 2022, 12(10), 1611; https://doi.org/10.3390/met12101611 - 26 Sep 2022
Cited by 2 | Viewed by 756
Abstract
Titanium has been one of the traditional metals used in the medical industry since 1940. This work modeled and simulated a hip-joint replacement implant using Creo 5.0 and DEFORM 3D (v11.0), respectively. Four titanium-based billets were modeled; out of four billets, three billets [...] Read more.
Titanium has been one of the traditional metals used in the medical industry since 1940. This work modeled and simulated a hip-joint replacement implant using Creo 5.0 and DEFORM 3D (v11.0), respectively. Four titanium-based billets were modeled; out of four billets, three billets were coated with a specified thickness, and one was uncoated. Among the three coated billets, one billet was coated with a 500-micron and two billets coated with a 1000-micron thickness. At the end of the simulation, the coating materials formed patches on the surface of the forged parts. The coating material Ti-6Al-4V (high O2) produced excellent mechanical properties in contrast to the CP-Ti material, which displayed low mechanical properties and did not match the core property. Hence, it was suggested to provide a bulk coating of Ti-6Al-4V (high O2) on the billet to improve the physio-mechanical properties and biocompatibility. Four points were selected on the surface of the forged parts at different locations for identifying the property variations concerning forging time. Results found that coating thickness required more on the side surface of the billet material than on the upper and lower surfaces to enhance its properties. Full article
(This article belongs to the Special Issue Advancements in Machining Technologies of Titanium-Based Alloys)
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Article
In-Process Fingerprints of Dissimilar Titanium Alloy Diffusion Bonded Layers from Hole Drilling Force Data
Metals 2022, 12(8), 1353; https://doi.org/10.3390/met12081353 - 15 Aug 2022
Viewed by 734
Abstract
The manufacture of components that have specific material properties in subcomponent regions is highly desired in many sectors. However, it is challenging to achieve via conventional ingot-wrought and joining processing routes. Recently, diffusion bonding titanium alloy powder using field assisted sintering technology (FAST) [...] Read more.
The manufacture of components that have specific material properties in subcomponent regions is highly desired in many sectors. However, it is challenging to achieve via conventional ingot-wrought and joining processing routes. Recently, diffusion bonding titanium alloy powder using field assisted sintering technology (FAST) has demonstrated that multi-material billets can be manufactured. Such billets still need to be machined into final net shaped components. The machinability and machining strategy of such components needs to be better understood if manufacturing of multi-material components is to be economically viable. This is the first study where drilling machinability of FAST diffusion bonded titanium alloys has been investigated. Location indexed force and torque feedback in-process fingerprinting is utilised during the drilling of multi-material titanium alloy billets. The in-process fingerprinting enabled rapid identification of the types and layering order of alloys within the FAST billets. In addition to force feedback, the hardness, hole surface topography and subsurface microstructure were characterised. Although hardness was found to contribute to variation in bond to bond machinability, results highlighted how alloy chemistry and bond composition are intrinsic to the machining directionality and significantly influence the machined surface quality and process stability. The work demonstrates that machining strategy of multi-material drilling needs to be tailored with respect to direction and diffusion bonded alloy pairing to avoid undesirable surface and subsurface damage at bond locations. Full article
(This article belongs to the Special Issue Advancements in Machining Technologies of Titanium-Based Alloys)
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Article
Machinability Analysis of Finish-Turning Operations for Ti6Al4V Tubes Fabricated by Selective Laser Melting
Metals 2022, 12(5), 806; https://doi.org/10.3390/met12050806 - 07 May 2022
Cited by 2 | Viewed by 874
Abstract
With the advent of additive manufacturing as an advanced technology for the fabrication of titanium components, there is a pressing need to investigate the machinability of parts produced using these techniques compared to components made with conventional wrought methodologies. The motivation for this [...] Read more.
With the advent of additive manufacturing as an advanced technology for the fabrication of titanium components, there is a pressing need to investigate the machinability of parts produced using these techniques compared to components made with conventional wrought methodologies. The motivation for this study was to investigate the influences of machining parameters, especially cutting depth, on the machinability of selective laser melted (SLMed) Ti6Al4V tubes, by analyzing the cutting responses, including cutting forces, machined surface roughness and tool wear at varying cutting parameters. Generally, it can be inferred that specific cutting tools used to machine wrought titanium components can also be used for SLMed parts when carrying out finish-machining operations. Cutting forces in the machining of SLMed workpieces could be up to 70% higher than those in machining the wrought counterparts. In contrast, the tool-wear analysis correspondingly showed larger tool-workpiece engagement area on the tool rake face for tools used for machining wrought parts. Adhesion on the cutting edge in the form of built-up edge and attrition of the tool surface were found to be the two most dominant tool-wear mechanisms, and the oxidation condition of the tool surface in machining SLMed parts was more severe (about 8% and 21%). Vibration analysis was also carried out, but no significant difference between the SLMed and wrought workpieces was observed, and the quality of the machined surface was similar. Full article
(This article belongs to the Special Issue Advancements in Machining Technologies of Titanium-Based Alloys)
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Article
Understanding the Micro-Mechanical Behaviour of Recast Layer Formed during WEDM of Titanium Alloy
Metals 2022, 12(2), 188; https://doi.org/10.3390/met12020188 - 20 Jan 2022
Cited by 5 | Viewed by 1061
Abstract
In the course of wire electro-discharge machining (WEDM), the unavoidable and undesirable formation of a recast layer on titanium (Ti) alloy was observed to have taken place. As a result, subsequent processing steps are required to remove this recast layer. In order to [...] Read more.
In the course of wire electro-discharge machining (WEDM), the unavoidable and undesirable formation of a recast layer on titanium (Ti) alloy was observed to have taken place. As a result, subsequent processing steps are required to remove this recast layer. In order to facilitate its removal, this study investigates the micro-mechanical properties of the said recast layer to better understand them. To that end, micro-pillars were fabricated on a recast layer after which in situ micro-pillar compression and nanoindentation were carried out. The in situ compression technique helps visualize deformation of materials in real time with corresponding features in stress–strain curves. The recast layer exhibits relatively brittle behaviour associated with the heat-affected zone (HAZ) and base alloy. Whereas the base alloy experienced substantial work hardening as evidenced by the formation of slip/shear bands, the recast layer was found to break down under external loading without any visible strain accommodation. This understanding of the recast layers could facilitate the design of effective removal operations, saving time and money. In addition, the recast layer might be useful in some applications. Full article
(This article belongs to the Special Issue Advancements in Machining Technologies of Titanium-Based Alloys)
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