Titanium and nickel alloys are used in the creation of components exposed to harsh and variable operating conditions. Such components include thin-walled structures with a variety of shapes created ...using milling. The driving factors behind the use of thin-walled components include the desire to reduce the weight of the structures and reduce the costs, which can sometimes be achieved by reducing the machining time. This situation necessitates, among other things, the use of new machining methods and/or better machining parameters. The available tools, geometrically designed for different strategies, allow working with similar and improved cutting parameters (increased cutting speeds or higher feed rates) without jeopardizing the necessary quality of finished products. This approach causes undesirable phenomena, such as the appearance of vibrations during machining, which adversely affect the surface quality including the surface roughness. A search is underway for cutting parameters that will minimize the vibration while meeting the quality requirements. Therefore, researching and evaluating the impact of cutting conditions are justified and common in scientific studies. In our work, we have focused on the quality characteristics of horizontal thin-walled structures from Tisub.6Alsub.4V titanium alloys obtained in the milling process. Our experiments were conducted under controlled cutting conditions at a constant value of the material removal rate (2.03 cmsup.3⁄min), while an increased value of the cut layer was used and tested for use in finishing machining. We used three different cutting tools, namely, one for general purpose machining, one for high-performance machining, and one for high-speed machining. Two strategies were adopted: adaptive face milling and adaptive cylindrical milling. The output quantities included the results of acceleration vibration amplitudes, and selected surface topography parameters of waviness (Wsub.a and Wsub.z) and roughness (Rsub.a and Rsub.z). The lowest values of the pertinent quantities were found for a sample machined with a high-performance tool using adaptive face milling. Surfaces typical of chatter vibrations were seen for all samples.
As a dielectric, biolubricant (vegetable oil) cannot maximize the efficiency of electrostatic atomization minimum quantity lubrication (EMQL). The lecithin-enhanced technology is expected to solve ...this technical bottleneck. The effects of lecithin on the electrophysiological properties of biolubricant (soybean oil) were investigated. Lecithin can increase the conductivity, viscosity, and charge mass ratio and reduce the surface tension of soybean oil. Comparative experiments show that the maximum average temperature rise of workpiece surface with MQL is 241.6 °C. The value under flooding, EMQL, and L+EMQL is reduced by 28.97%, 42.8%, and 48.92%, respectively, compared with MQL. The influence of lecithin mixing ratio on grinding performance was discussed. The minimum surface roughness value (0.49 µm) is obtained at the mixing ratio of 2:10.
•A new grinding method of lecithin bioubricant EMQL was proposed.•The effects of lecithin addition on physical characteristics of vegetable oil were studied.•Several groups of comparative experiments are carried out to verify the effectiveness of L+EMQL lubrication method.•L+EMQL method can reduce the grinding temperature and improve the surface quality of workpiece effectively.•Lecithin has self-assembly behavior in non-polar oil, which can improve its lubrication performance effectively.
Titanium is a good example of a material that is globally recognized for its outstanding properties, making it desirable for a range of industries. Titanium and its alloys are utilized in a wide ...range of industries, including aerospace, automotive and high performance leisure equipment. This Special Issue of Metals focusing on titanium contains a range of articles based on research into this fascinating material and its wide range of alloys. For applications that can withstand the high basic cost of titanium it is shown that the unique properties of the material have the potential to provide further performance improvements to existing industries, whilst offering new opportunities to emerging markets.
Duplex aging is one of the common heat treatments in titanium alloys. The microstructure introduced in the first-step aging has an effect on the growth/dissolution of alpha in the second-step aging. ...In the present work, a beta + alpha.sub.acicular microstructure is preset in Ti-55531 (Ti-5Al-5Mo-5V-3Cr-1Zr wt%) alloy. The isochronal and isothermal phase transformation kinetics in the second-step aging is studied by combining the dilatometer test with microstructure characterization and local composition mapping. The phase transformations and corresponding temperature ranges are determined as beta right arrow alpha.sub.acicular 643-845 K and alpha.sub.acicular right arrow beta 845-1130 K by isochronal annealing. A TTT diagram for isothermal transformation kinetics is plotted based on the transformed phase fraction and reproduced by Johnson-Mehl-Avrami theory. The calculated kinetic curves are in good agreement with experiment ones. The C-shaped TTT curves verify the classical nucleation and growth of alpha in the second-step aging. In comparison with Ti-55531 alloy with preset beta + alpha.sub.lath microstructure (in authors' previous work), the alpha precipitation exhibits prolonged incubation period and slowed average transformation rate, which is evidenced by a right shift of C-curves for the alpha precipitation portion along the time axis. However, the C-curves of alpha dissolution show a left shift on the TTT diagram. The precipitation kinetics of alpha aciculae from dilatometry is synchronous with that obtained from the diffusion of Al detected in STEM mapping, while the diffusion of slow-diffusion elements lags behind the structural transformation. The TTT diagram and the dataset of microstructure features obtained in the present work can be employed to optimize processing in duplex aging.
The article discusses the properties and features of heat-resistant titanium alloys. The microstructure of a new titanium alloy VT41, its mechanical and service properties after various processing ...modes are presented. The main problems in the machining of difficult-to-machine titanium alloys are considered. The developed mathematical model of the formation of errors in turning titanium alloys, taking into account thermal deformations and dimensional wear of the cutting tool, elastic deformations of the technological system, is described. The paper presents the results of experimental research on turning of heat-resistant titanium alloy VT41 on a multi-parameter stand.
In this article, we subjected the Ti60 alloy to solid-solution treatment at 1020 °C and aging treatment at 600 °C, respectively, achieving a bimodal microstructure. The microstructures obtained after ...aging treatment showed no significant difference in the primary α-phase content, size, and width of the lamellar α phase. This suggests that the final microstructure morphology is primarily determined by the solid-solution temperature, with the aging process exerting less pronounced effects on microstructural alterations. Furthermore, we investigated the effect of solid-solution and aging treatment on the crystallographic orientation evolution of the secondary α phase (αsub.s) in the near-α titanium alloy Ti60. The αsub.s phase displays a random orientation in solid-solution treatment sample, while it demonstrated a preferential {0 1 −1 0} orientation after aging treatment. This interesting phenomenon is attributed to the enhanced variant selection resulting from the dissolution of variant near 60° and 90° during aging. Furthermore, the αsub.s with {0 1 −1 0} orientation nucleated at the grain boundary and coalesced into larger αsub.s lath with increasing aging time, further contributing to the αsub.s {0 1 −1 0} texture.
Background: Is abrasive blasting accompanied by the phenomenon of driving abrasive particles into the conditioned material? Methods: Three hundred and fifteen cylindrical disks of three types of ...metal alloy (chromium/cobalt, chromium/nickel, titanium, and sintered zirconium dioxide) were divided into four groups (n = 35) and sandblasted at pressures of 0.2, 0.4, or 0.6 MPa with aluminum oxide (Alsub.2Osub.3), grain size 50, 110, or 250 μm. Then, the surface topography was examined using a scanning microscope, and the amount of embedded grain was measured using quantitative metallography. For each group, five samples were randomly selected and subjected to Vickers hardness testing. In the statistical analyses, a three-factor analysis of variance was carried out, considering the type of material, the size of gradation of the abrasive, and the amount of pressure. Results: The smallest amounts of embedded abrasive (2.62) were observed in the ZrOsub.2 treatment, and the largest (38.19) occurred in the treatment of the Ti alloy. An increase in the gradation and the pressure were a systematic increase in the amount of embedded grain. Conclusions: After abrasive blasting, abrasive particles were found on the surface of the materials. The amount of driven abrasive depends on the hardness of the processed material.
The present study aims at revealing the relationships between hydrogen concentration and phase structure, as well as microstructure modification in the beta-metastable beta-21S titanium alloy. The ...beta-bcc phase can accommodate a large number of interstitial atoms, and hydrogenation by means of molecular hydrogen gas was employed in the present work. The phase structure as well as the microstructure of this alloy was found to be strongly dependent on hydrogen concentration. At lower hydrogen concentration (H/M less than or equal to 0.300), the microstructure consisting of the single beta-phase revealed that the interstitially dissolved hydrogen atoms expanded the bcc lattice and inhibited the decomposition of the beta phase upon cooling. The introduction of hydrogen beyond H/M = 0.300 was found to generate a large amount of internal stresses in the microstructure inducing the formation of metastable phases alpha'' in the form of lamellae and omega in the form of nanoparticles. The generation of the nanosized omega-phase was presumed to relax the strain caused by the volume expansion (2.28%) from the hydrogen-containing beta phase to the alpha'' martensite.
It remains a popular question whether rare earth oxides encourage reinforcing phases to the uniform distribution in cermet coating to improve the mechanical properties. This study applied laser ...cladding to prepare the TiAl/WC/CeOsub.2 MMC cermet coatings on the TC21 alloy substrate. The effects of CeOsub.2 content on the phase composition, microstructure formation, evolution mechanism, and properties of cermet coatings were investigated. Results show that the incorporation of CeOsub.2 did not change the phase of composite coating, but the shape of the TiC phase has a close relation to the CeOsub.2 content. CeOsub.2 enhanced the fluidity of the molten pool, which further encouraged the TiC/Tisub.2AlC core-shell reinforcement phase. With the increase in CeOsub.2 content, the optimized coating contributed to homogenous microstructure distribution and fine grain size. Owing to the hard phases strengthening and dispersion strengthening effects of CeOsub.2, the microhardness of the composite coatings was all significantly higher (almost 1.6 times) than that of the substrate. Importantly, the addition of CeOsub.2 significantly improved the wear resistance of the composite coating. This work provides a certain reference value for the study of surface strengthening of key parts in the aerospace field.
