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Ti-6AL–4 V alloy, is a widely recognised titanium alloy. It is responsible for over half of all applications involving titanium alloys, primarily due to its attractive mechanical and physical properties that make it a highly desirable material. For most applications, the vast majority of working components require permanent joining. The conventional fusion welding of titanium often leads to oxidation losses and increased brittleness. Friction stir welding improves weld quality by preventing heating the metal past its melting point. Despite the fact that Friction Stir Welding (FSW) of Ti6Al4V alloys has advantages over other welding methods, the process parameters have a major impact on the weld microstructure and mechanical properties. In most cases, a defect-free weld with the ideal microstructure can be achieved by selecting the best process parameters, such as the tool material, tool geometry, traverse speed, and rotational speed. This paper briefly reviews Ti-6Al-4 V alloy friction stir welding developments and understandings. Variation in friction stir welding process parameters like tool rotation and translation speed affects weld region microstructure constituents, defects, and mechanical properties. This paper establishes a crucial relationship between process variables, microstructure, defects, and mechanical properties. Summarising and tabulating recent developments for easy understanding and adoption is emphasised. [ABSTRACT FROM AUTHOR]

Titanium alloy can be found in numerous applications, such as chemical, aerospace, and energy industries, among other sectors, due to its excellent performance. Nevertheless, the possible uses of a variety of titanium-based alloys have been greatly restricted by their low hardness and inadequate resistance to wear. Therefore, in this research work, WC–Cu composite electrode assisted electrical discharge coating (EDC) is used for improving microhardness (MH) and surface integrity of Ti–6Al–4V alloy. By utilizing powder composite electrode, the conductivity of the electrode can be increased, which provides controlled electric spark, resulting in uniform deposition. In order to increase the rate of deposition, the terminal of the EDM has been changed as WC–Cu composite electrode as anode and workpiece as cathode. Response surface methodology is used for studying the variables including compacting pressure (MPa), discharge current (I), pulse on time (Ton). In addition, microstructure, elemental analysis and coating interface of deposited Ti–6Al–4V alloy are investigated through scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The surface roughness of 8.86 µm was achieved at 400 MPa, 6 A, and 40 µs. The maximum MH of 988 HV was obtained at 400 MPa, 10 A, and 80 µs. The MH of the deposited layer is around 2–3 times harder than base material. Moreover, a greater adhesion strength coated layer was ∼118 N, which permits the alloy to have improved wear resistance. It was concluded that using a high-pressure electrode with lower settings resulted in an improved surface finish, while higher settings led to increased MH. [ABSTRACT FROM AUTHOR]

Ti-6Al-4V alloys with a thermal barrier coating (TBC) have been applied in aeronautical components as turbine blades to provide oxidation resistance and thermal protection, enabling higher operating temperatures and extending component lifespan. Research into TBCs with laser surface modification has investigated improving their mechanical and thermal properties. This study assessed the creep behavior of Ti-6Al-4V alloy with a TBC, where the coating was applied via CO2 laser-remelted plasma spraying. Creep tests were conducted at a constant temperature and a load ranging from 500 to 700 °C at 125 MPa. The microstructure and fractography of the specimens were also investigated. The investigation also included microstructural and fractographic analyses of the specimens. The results indicate that the laser-remelted TBC provided effective thermal protection and increased oxidation resistance, with the stationary creep rate at 600 °C reduced by 50% and the creep rupture life extended by 20%. Observations revealed typical ductile fractures characterized by equiaxed dimples and a homogeneous microstructure with an equiaxed dual-phase (α+β) structure near the fracture zone. [ABSTRACT FROM AUTHOR]

Cutting fluid has been widely used to enhance the heat dissipation of cutting systems. However, whether cutting fluid can fully play its role is closely correlated with its thermophysical characteristics, such as viscosity, surface tension, etc. In this work, to study the effect of the thermophysical characteristics of cutting fluid on cutting performance, three green vegetable oils (semi-synthetic fluid (L1), rapeseed oil (L2), canola oil (L3)) were selected as cutting fluids of the MQL system, and differences in cutting performance were compared and analyzed under varied lubrication environments. Firstly, the thermophysical characteristics of the vegetable oils were determined by experimental methods. Afterwards, parameters, including tool wear, cutting force, and temperature, as well as the quality of machined workpieces, were selected to evaluate cutting performance, and essential reasons for the difference in cutting performance under varied lubrication environments were clarified. The results demonstrated that the cutting force, cutting temperature, and tool wear produced in the three MQL environments were lower than those in the dry cutting environment, while only the L1 and L2 MQL environments exhibited higher machined surface quality than the dry cutting environment. Moreover, obvious differences in cutting performance under the three MQL environments were also observed due to the different thermophysical characteristics of the three vegetable oils. The best cutting performance was achieved when L2 was used as the MQL cutting fluid. The efforts of this study will give an important reference for the choosing of green cutting fluid in the cutting process of difficult-to-cut materials and be of great significance for accelerating the development of green processing. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) is an effective method for enhancing the fatigue life and mechanical properties of Ti alloys. However, there is limited research on the effects of LSP on crystal structure and dislocation characteristics. In this study, Ti-6Al-4V alloy was subjected to laser shock peening with varying laser power levels. The influence of laser power on the microstructure of Ti-6Al-4V was investigated, with a focus on the evolution of the cross-sectional structure, crystallographic features, and dislocation behavior. These characteristics were analyzed using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Following laser shock peening, the surface grains of Ti-6Al-4V alloy exhibited a distinct preferred orientation and underwent significant refinement, resulting in the formation of nanocrystals. At a laser power of 8 J, the texture strength decreased to 5.19 mud. As laser power increased, a denser dislocation structure and high-density dislocation regions formed at the surface, and the subgrain size further decreased, reaching 66 nm at 8 J. These findings provide valuable insights into grain refinement and property enhancement, contributing to the understanding of process–microstructure–property relationships. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive numerical investigation to simulate heat transfer and residual stress formation of Ti-6Al-4V alloy during the Laser Powder Bed Fusion process, using a finite element model (FEM). The FEM was developed with a focus on the effects of key process parameters, including laser scanning velocity, laser power, hatch space, and scanning pattern in single-layer scanning. The model was validated against experimental data, demonstrating good agreement in terms of temperature profiles and melt pool dimensions. The study elucidates the significant impact of process parameters on thermal gradients, melt pool characteristics, and residual stress distribution. An increase in laser velocity, from 600 mm/s to 1500 mm/s, resulted in a smaller melt pool area and faster cooling rate. Similarly, the magnitude of residual stress initially decreased and subsequently increased with increasing laser velocity. Higher laser power led to an increase in melt pool size, maximum temperature, and thermal residual stress. Hatch spacing also exhibited an inverse relationship with thermal gradient and residual stress, as maximum residual stress decreased by about 30% by increasing the hatch space from 25 µm to 75 µm. The laser scanning pattern also influenced the thermal gradient and residual stress distribution after the cooling stage. [ABSTRACT FROM AUTHOR]

In this paper, a novel hybrid forging process is proposed for block materials with high specific strength based on the traditional forging process. A prestressing system is established first by clamping the forging using a hydraulic press process in the hybrid process, then rapidly impacting the system using hammer impact process in order to activate and amplify the prestressing force. To achieve the novel hybrid process, integrated equipment is designed based on the structure characteristics of both the press and the hammer, its dynamic characterization is analyzed through simulations to obtain the results of multi-objective optimization. In this study, effectiveness of the novel hybrid forging process by forging Ti-6Al-4V alloy is first reported. Experimental results show that the plastic deformation of the forgings can increase by up to about 3 % and energy loss of equipment elastic deformation can reduce about 25.8 % in the hybrid process, compared to the single hydraulic press process. In particular, microstructure of forgings occurs finer grain size and higher and more uniformly distributed dislocation density. This study reveals the potential of the novel hybrid forging process technology, which lays a solid foundation for expanding its application in forging industrial production about high specific strength material. [ABSTRACT FROM AUTHOR]

Titanium and titanium alloys exhibit low density, high strength and excellent corrosion resistance, and have become workhorses in modern aerospace and chemical processing industries. Recently, Ti-6Al-4V alloy has been manufactured through metal injection molding (MIM). MIM is widely utilized in various manufacturing industries due to the near-net-forming process, especially in the preparation of difficult-to-deform high-temperature alloys. Sintering temperature is vital to ensuring good tensile mechanical properties. In this work, Ti-6Al-4V alloy was sintered under various sintering temperatures, from 1150 to 1250 °C. The effect of sintering temperature on the mechanical properties was evaluated. The tensile test results exhibited that a yield strength of 896.35 MPa, an ultimate tensile strength of 980.83 MPa and plastic elongation of 9.61% were produced at 1150 °C for 4 h; a yield strength of 877.23 MPa, an ultimate tensile strength of 981.92 MPa and plastic elongation of 7.74% were produced at 1200 °C for 4 h; and a yield strength of 923.33 MPa, an ultimate tensile strength of 1002.24 MPa and plastic elongation of 6.57% were produced at 1250 °C for 4 h. [ABSTRACT FROM AUTHOR]

This study explores the dynamic interaction between environmentally sustainable plasma enhancer and quencher agents during the incorporation of SiO2 into a TiO2 layer, with the primary objective of simultaneously augmenting protective and bioactive attributes. This enhancement is realized through the synergistic utilization of Tetraethyl orthosilicate (TE) and Stevia (ST) within a plasma-assisted oxidation process. To achieve this goal, Ti–6Al–4V alloy underwent oxidation in an electrolyte solution containing acetate-glycerophosphate, with the addition of TE and ST separately and in combination. TE, as a silicon oxide (SiO2) precursor, facilitates the creation of a calcium-rich, rough, porous layer by undergoing hydrolysis to generate silanol groups (Si–OH), which subsequently condense into silicon-oxygen-silicon (Si–O–Si) bonds, resulting in SiO2 formation. In contrast, ST acts as a plasma quencher, absorbing highly reactive plasma species during the oxidation process, reducing energy levels, and diminishing sparking intensity. The combination of TE and ST results in moderate sparking, balancing Stevia's quenching effect and TE's sparking influence. As a result, this coating exhibits enhanced corrosion resistance and bioactivity compared to using either ST or TE alone. The study highlights the potential of this synergistic approach for advanced TiO2-based coatings.

This paper presents the results of research on the kinetics of transformations in the two-phase (α + β) Ti-6Al-4V alloy. The transformation start and end temperatures during heating at different rates were determined using a dilatometer. A modified dilatometer was employed, equipped with an acoustic emission measurement apparatus and software enabling the assessment of sample dimensional changes during heating and cooling. The results were obtained in the form of dilatometric curves. Additionally, the occurrence of the transformation was confirmed by acoustic emission signals. In the study of the Ti-6Al-4V alloy, acoustic emission refers to the application of this non-destructive technique to monitor the alloy's behavior during thermal processes. As the temperature increased, regardless of the heating rate, the α→β transformation was observed to occur after exceeding 900 °C. Within the transformation range, acoustic emission signals were recorded. Moreover, it was found that the applied research methods enabled the identification of signal components originating from the transformation. The application of acoustic methods in the analysis of phase transformations opens new possibilities for their use in industry. [ABSTRACT FROM AUTHOR]

In this study, a nanofluid ultrasonic atomization minimum quantity lubrication (MQL) system was employed for grinding and processing titanium alloy (Ti-6Al-4V). Nanoparticles in the nanofluid were dispersed through the ultrasonic atomization MQL system to improve the lubrication efficiency. This system is a grinding manufacturing innovation on lubrication technology. First, a robust design method optimizes the grinding parameters of force ratio, temperature, and surface roughness of each quality characteristic. Surface integrity is considered a key component metric in grinding. Therefore, various images of the grinding surface quality were collected to establish a complete titanium alloy grinding image database. The convolutional neural network (CNN) technique was used to establish a model with high accuracy and automatic recognition of the surface quality after grinding, which is classified as Good, Plowing, Crushing pits, and Bad. This study employed VGG-19, GoogLeNet, ResNet-50, and AlexNet for modeling and testing comparison. Different hyperparameter configurations will affect each model's learning speed and performance. Therefore, their hyperparameter optimizations were performed before establishing our CNN model for classification. After optimization, the average accuracy of the four models can be improved by 3.75–12%, which can quickly improve the performance of the CNN model systematically. This study verified and validated our model. The findings show that this research method can be used by the industry in the actual grinding process monitoring and identification of the grinding quality of Ti-6Al-4V. [ABSTRACT FROM AUTHOR]

The finite element modeling method has been widely applied in the modeling of the cutting process to characterize the instantaneous and microscale deformation mechanism that was difficult to obtain using physical experiments. The lubrication and cooling conditions, such as minimum quantity lubrication and cryogenic liquid nitrogen, affect the thermo-mechanical behaviors and machined surface integrity in the cutting process. In this work, a grain-size-dependent constitutive model was used to model orthogonal cutting for Ti-6Al-4V alloy with MQL and LN2 conditions. The cutting forces and chip morphologies that were measured in the cutting experiments of Ti-6Al-4V alloy were used to validate the simulated forces. The relative errors between the measured and simulated principal forces were less than 8%, while the relative errors of thrust forces were less than 19%. The predicted chip morphologies and surface grain refinement agreed well with the experimental results under the conditions with different uncut chip thicknesses and edge radii. Additionally, the relationship between the plastic displacement and grain refinement, as well as the microhardness and residual stresses under MQL and cryogenic conditions, were discussed. This work provides an effective modeling method for the orthogonal cutting of Ti-6Al-4V alloy to understand the mechanism of the plastic deformation and machined surface integrity under the MQL and LN2 conditions. [ABSTRACT FROM AUTHOR]

In the present study, a hybrid machining process known as an electrochemical cut-off grinding (ECCG) is used for grinding of Inconel-718 material. The specimen (superalloy) contains nickel as major component. It cannot be machined conventionally due to its outstanding properties. During the electrochemical grinding of Inconel 718, the author examines the effects of input voltage (v), tool feed rate (mm/min), electrolytic concentrations (g/ltr), electrolytic flow rate (ltr/min), and grinding speed (rpm) on responses such as material removal rate (MRR) and surface roughness (Ra). The tests contains the bronze-bonded diamond abrasive grinding wheel. The MRR and surface roughness of Inconel 718 and titanium super alloy during the ECCG process are also compared in this research project. Based on the findings of the studies, it appears that the tool feed rate, the flow rate of the electrolyte, and the rotation of the grinding wheel are the maximum influential parameters for enhancing MRR and surface finish during electrochemical cut-off grinding of Inconel 718. Tool feed rates of 0.09 mm/min to 0.18 mm/min, electrolyte flow rates of 5 ltr/min to 8 ltr/min, and grinding wheel speeds of 800 rpm to 2000 rpm are the ideal influencing factors. The comparative analysis demonstrates that Ti-6Al-4 V alloy cannot match Inconel 718's machinability. Compared to Ti-6Al-4 V alloy, Inconel-718 has an average material removal rate that is up to 1.73 times higher and an average surface quality that is up to 3.16 times better. [ABSTRACT FROM AUTHOR]

This study investigates the effects of various surface modification techniques on the Ti-6Al-4V alloy for biomedical applications. Mechanical treatments (sandblasting, shot peening) and electrochemical corrosion using different electrolytes were employed to modify surface characteristics. Surface morphology, roughness, hardness, and chemical composition were analyzed using SEM, profilometry, and Raman spectroscopy. Cell attachment studies revealed that combined treatments, particularly shot peening followed by HF/HNO3 etching, significantly enhanced cell adhesion and distribution. The results demonstrate the potential for tailoring Ti-6Al-4V surfaces to optimize biocompatibility and osseointegration properties for dental and orthopedic implants. [ABSTRACT FROM AUTHOR]

A SiC-SiO 2 nano-composite coating was prepared via a novel liquid-phase plasma-assisted particle deposition and sintering (LPDS) method to enhance the oxidation resistance of the Ti-6Al-4V alloy. For comparison, a conventional plasma electrolytic oxidation (PEO) ceramic coating is fabricated on the Ti-6Al-4V alloy. The microstructure and formation mechanisms of both ceramic coatings were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results indicated that the thickness of the SiC nano-composite coating (∼40 μm) increased significantly by 285 % compared to the PEO coating (∼14 μm). The microstructural evolution and isothermal oxidation performance of the PEO and SiC-SiO 2 nano-composite coating were comparatively investigated at 800 °C. After 100 h, the thickness gain of the SiC-SiO 2 nano-composite coating (∼14 μm) was lower than that of the PEO coating (∼26 μm). The improved oxidation performance is primarily attributed to the outermost layer containing abundant SiC nanoparticles, which transform into SiO 2 during the oxidation process and effectively inhibiting the inward penetration of oxygen. [ABSTRACT FROM AUTHOR]

Ti–6Al–4V and AZ31B alloy sheets were joined in lap joint configuration using cold metal transfer welding with a synergic power source. The torch angle was kept approximately 45° away from the top plate. Wire feed speeds (WFSs) have been varied from 3.0 m/min to 7.0 m/min. Cold metal transfer welding results in good deposition of weld metal at higher WFSs but at the cost of poor bonding and defects. Joints of the best qualities were fabricated at a WFS of 3.0 m/min and a welding speed of 0.6 m/min. The torch angle assisted in the proper deposition of AZ31B weld metal with a good bond between weld metal and Ti–6Al–4V base metal. Microstructural analysis confirms the joint interface integrity by revealing the absence of defects. Also, there is a significant variation among the grain morphology of weld region, transition zone and base metal. The presence of several oxides (MgO4, Al2O3, etc.) and intermetallics (Mg17Al12, Mg7Zn3, AlMg4Zn11, etc.) is indicated by metallurgical analyses. Tensile-shear tests revealed that the joints could sustain the maximum load of 1871 N. Fractography reveals the mixed mode of fracture containing majority brittle, and a ductile failure at a few locations. The unusual fracture at a few locations indicates the presence of oxides in these regions. [ABSTRACT FROM AUTHOR]

Direct Metal Laser Sintered (DMLSed) titanium grade 5 alloy (Ti-6Al-4V alloy) is one of the widely used 3D Printed alloy in structural aerospace components. In the present work, the effect of laser sintering on the microstructure and the mechanical and corrosion behavior of DMLSed Ti-6Al-4V alloy has been studied. The samples were printed by varying the laser power and scan speed over a wide range, one parameter at a time. The fabricated Ti-6Al-4V alloy predominantly showed the martensitic structure, which governs the overall performance of the printed alloy. The mechanism of martensitic laths formation in the microstructures is presented to understand their evolution and effect on the mechanical behavior. As a result, the tensile strength and hardness of the fabricated Ti-6Al-4V alloy increased by nearly 33 and 5%, respectively, when the laser power was increased from 150 to 300 W at a fixed scan speed of 1250 mm/s. An 8% increase in tensile strength and 1-2% increase in hardness was observed when the scan speed was increased from 500 to 1250 mm/s, at a fixed laser power of 150 W. The corrosion resistance of fabricated Ti-6Al-4V alloy improved with an increase in laser power but deteriorated with an increase in scan speed. This study led to new insights into the microstructural evolution of direct laser-sintered Ti-6Al-4V alloy, which is likely to assist in producing superior quality DMLS parts. [ABSTRACT FROM AUTHOR]

ABSTRACT The high cycle fatigue (HCF) behaviors of an additively manufactured (AM) Ti–6Al–4V alloy with fully lamellar microstructures processed electron beam powder bed fusion (EB‐PBF) and wire‐fed electron beam directed energy deposition (Sciaky) routes were compared. Ultrasonic fatigue (USF) testing at the stress ratio of R = −1 was applied to monitor the growth of small cracks initiated at surface micronotches. Crack growth rates lower than 10−8 (m/cycle) at ΔK = 6 MPa·m1/2 were measured in samples processed by both methods. The finer α lath thickness (~1 μm) of the Sciaky samples resulted in a slower fatigue crack growth rate than the EB‐PBF samples with coarser laths. The interaction of cracks with the lamellar microstructures was characterized by electron backscatter diffraction. Crack propagation largely followed the lath interfaces in the Sciaky samples, whereas cracks cut across colonies in the EB‐PBF samples. Different fatigue fracture surface characteristics were observed for the EB‐PBF and Sciaky samples. [ABSTRACT FROM AUTHOR]

This study investigates the impact of tightening torque (preload) and the friction coefficient on stress generation and fatigue resistance of a Ti-6Al-4V abutment screw with an internal hexagonal connection under dynamic multi-axial masticatory loads in high-cycle fatigue (HCF) conditions. A three-dimensional model of the implant–abutment assembly was simulated using ANSYS Workbench 16.2 computer aided engineering software with chewing forces ranging from 300 N to 1000 N, evaluated over 1.35 × 107 cycles, simulating 15 years of service. Results indicate that the healthy range of normal to maximal mastication forces (300–550 N) preserved the screw's structural integrity, while higher loads (≥800 N) exceeded the Ti-6Al-4V alloy's yield strength, indicating a risk of plastic deformation under extreme conditions. Stress peaked near the end of the occluding phase (206.5 ms), marking a critical temporal point for fatigue accumulation. Optimizing the friction coefficient (0.5 µ) and preload management improved stress distribution, minimized fatigue damage, and ensured joint stability. Masticatory forces up to 550 N were well within the abutment screw's capacity to sustain extended service life and maintain its elastic behavior. [ABSTRACT FROM AUTHOR]

A coating of the CoCrCu base powder was prepared on the surface of Ti-6Al-4V alloy by laser cladding/remelting with a fibre laser. The effect of the different melt materials such as Tribaloy, Cu and Si3N4 on the microstructure and wear resistance of these laser clad coatings were investigated. The CoCrCu laser clad coating had a good metallurgical bond with a Ti-6Al-4V alloy substrate and consisted primarily of TiC, Cu4Ti3, (Co, Cr)2Ti. The microhardness and wear resistance of this laser clad coating was increased over the as-received Ti-6Al-4V alloy due to the Cu base and the other intermetallics leading to second phase/the fine grain strengthening. A fine microstructure was obtained due to the remelting effect. [ABSTRACT FROM AUTHOR]