Tribological phenomena and tool wear mechanisms during machining of hard-to-cut TiAl6V4 aerospace alloy have been investigated in detail. Since cutting tool wear is directly affected by tribological phenomena occurring between the surfaces of the workpiece and the cutting tool, the performance of the cutting tool is strongly associated with the conditions of the machining process. The present work shows the effect of different machining conditions on the tribological and wear performance of TiB 2 -coated cutting tools compared to uncoated carbide tools. FEM modeling of the temperature profile on the friction surface was performed for wet machining conditions under varying cutting parameters. Comprehensive characterization of the TiB 2 coated vs. uncoated cutting tool wear performance was made using optical 3D imaging, SEM/EDX and XPS methods respectively. The results obtained were linked to the FEM modeling. The studies carried out show that during machining of the TiAl6V4 alloy, the efficiency of the TiB 2 coating application for carbide cutting tools strongly depends on cutting conditions. The TiB 2 coating is very efficient under roughing at low speeds (with strong buildup edge formation). In contrast, it shows similar wear performance to the uncoated tool under finishing operations at higher cutting speeds when cratering wear predominates.

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In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

Use of an alpha-beta (multiphase HCP-BCC) titanium alloy, Ti6Al4V, is ubiquitous in a wide range of engineering applications. The previous decade of finite element analysis research on various titanium alloys for numerous biomedical applications especially in the field of orthopedics has led to the development of more than half a dozen material constitutive models, with no comparison available between them. Part of this problem stems from the complexity of developing a vectorised user-defined material subroutine (VUMAT) and the different conditions (strain rate, temperature and composition of material) in which these models are experimentally informed. This paper examines the extant literature to review these models and provides quantitative benchmarking against the tabulated material model and a power law model of Ti6Al4V taking the test case of a uniaxial tensile and cutting simulation.

Abstract:A new family of physical vapor deposited (PVD) coatings is presented in this paper. These coatings are deposited by a superfine cathode (SFC) using the arc method. They combine a smooth surface, high hardness, and low residual stresses. This allows the production of PVD coatings as thick as 15 µm. In some applications, in particular for machining of such hard to cut material as compacted graphite iron (CGI), such coatings have shown better tool life compared to the conventional PVD coatings that have a lower thickness in the range of up to 5 µm. Finite element modeling of the temperature/stress profiles was done for the SFC coatings to present the temperature/stress profiles during cutting. Comprehensive characterization of the coatings was performed using XRD, TEM, SEM/EDS studies, nano-hardness, nano-impact measurements, and residual stress measurements. Application of the coating with this set of characteristics reduces the intensity of buildup edge formation during turning of CGI, leading to longer tool life. Optimization of the TiAlN-based coatings composition (Ti/Al ratio), architecture (mono vs. multilayer), and thickness were performed. Application of the optimized coating resulted in a 40-60% improvement in the cutting tool life under finishing turning of CGI.