TC4 Titanium Alloy Research Articles

Corrosion behavior of ZrO2-TiO2 composite coatings produced on titanium alloy via plasma electrolytic oxidation

TiO2-ZrO2 composite coating was fabricated on TC4 titanium alloy via plasma electrolytic oxidation (PEO) in an alkaline electrolyte composed of Na2SiO3 and KOH. The effect of the content of K2ZrF6 as an electrolyte additive on the microstructure, elemental composition, phase structure, thickness, hardness, adhesion and corrosion resistance of PEO coating was investigated. The results show that the addition of K2ZrF6 contributed to the enhancement of coating thickness (from 4.04 ± 0.62 μm to 11.44 ± 0.35 μm) and hardness (488.4 HV to 779.8 HV). As the K2ZrF6 concentration increased, both the quantity and diameter of micropores on the surface of the PEO coatings decreased firstly and then increased. The minimum porosity and pore size were obtained in the electrolyte containing 6 g/L K2ZrF6. The coatings were mainly composed of Ti, anatase TiO2 and rutile TiO2. EDS test proved that K2ZrF6 successfully participated in the PEO reaction. The composite coating prepared in silicate electrolyte system with 6 g/L K2ZrF6 exhibited the highest corrosion resistance. Furthermore, the formation mechanism of the ZrO2-TiO2 composite coating was discussed in detail.

Internal–State–Variable Based Unified Viscoplastic Constitutive Modeling of TC11 Titanium Alloy and Its Microstructure Evolution Simulation

Internal–State–Variable Based Unified Viscoplastic Constitutive Modeling of TC11 Titanium Alloy and Its Microstructure Evolution Simulation

Grain size dependence of microstructure and mechanical properties of nanocrystalline TC4 alloy studied by molecular dynamic simulation

Based on molecular dynamic simulation with tensile loading, the microstructure and tensile strength of TC4 titanium alloy are studied with nanocrystalline model. By varying the grain size while keeping the grain geometry the same, the Hall–Petch relationship is observed for average flow stress with average grain size d>15 nm, where the resistance to intragranular deformation is proportional to d-0.5. For d<15 nm, however, smaller grain size leads to smaller resistance to intergranular deformation in the form of grain boundary migration and diffusion, which leads to inverse Hall–Petch relationship. The analysis of displacement vector reveals the role of grain boundaries in restricting propagation of dislocations such as 13<11‾00>, which is responsible for FCC stacking fault inside HCP grain. In the heat treatment modeling under different temperatures, the fraction of grain boundary atoms decreases and thus the maximum tensile strength increases. On the other hand, the fraction of well-ordered atom increases, which can cause growth of existing grain and nucleation of minor BCC grain from previously grain boundary region before heat treatment.

Wear Mechanism of TC4 Titanium Alloy with TiN Coating against Self-Lubricating Fabric

Vapor deposition technology can improve the surface wear resistance of titanium alloys, and prepare lightweight and corrosion-resistant self-lubricating spherical plain bearings made of titanium alloys. However, titanium alloys with hard films can be worn by soft self-lubricating fabrics. This paper focuses on the wear problem of TiN coating on the surfaces of self-lubricating spherical plain bearings based on titanium alloys. Ring-to-plate wear tests were carried out to study the tribological properties of TiN coating on TC4 titanium alloy against self-lubricating fabric under different working conditions (load: 500–2000 N and speed: 100–500 r/min), along with the investigation of the wear mechanism of TiN coating, and the evaluation of applicable working conditions of GE15 type self-lubricating spherical plain bearings through swing tests. The results have revealed that TiN coatings can maintain a certain friction distance without wear. Increasing friction speed and load can make TiN coatings more prone to wear. A thick transfer film can protect the TiN coating from wear. The main wear mechanism is attributed to fatigue wear induced by the repeated formation and peeling of transfer films. The GE15 bearing has achieved a self-lubricating fabric wear of approximately 0.04 mm when the swinging for 500 m (25,000 times) is under a specific condition of 27 kN and 0.2 Hz without damaging the inner ring of the bearing. The bearing is suitable for swing conditions with applied loads below 27 kN. This study provides a fundamental understanding of designing self-lubricating spherical plain bearings made of titanium alloys.

Study on process of removing burrs from group holes in TC4 titanium alloy plate by non-synchronous rotation grinding

Study on process of removing burrs from group holes in TC4 titanium alloy plate by non-synchronous rotation grinding

Diffusion Welding for TC4 Titanium Alloy/T2 Copper with Vanadium Foil

TC4 titanium alloy (TC4) was vacuum diffusion welded to T2 copper (T2) with vanadium (V) foil as an interlayer. The influence of process parameters on elemental diffusion behavior, microstructure evolution, and shear performance of welded joints was explored. An obvious solid-solution diffusion zone appeared in the welded interface between TC4 and V, but no distinct diffusion zone formed in the joint interface of V/T2. The solid-solution phases of (Ti6, V)ss, (Ti3, V)ss, and (Ti, V7)ss appeared in the interface of TC4/V. The crystallographic orientations of (Ti6, V)ss, (Ti3, V)ss, and (Ti, V7)ss phases in high-resolution transmission electron microscope images were (002), (201), and (121), respectively. The lattice mismatch between (Ti6, V)ss and (Ti3, V)ss was calculated to be 11.9%. The activation energy to form a stable solid solution between titanium and vanadium was 226.6 kJ/mol. The highest shear strength of the welded joint reached 160 MPa, obtained at 860°C (1580°F) for 60 min. The joint fractured along the interface of V/T2, illustrating that the solid-solution structure between Ti and V was stronger than the metallurgical bonding between V and Cu. The fracture surface of the welded joints revealed a river pattern and ladder topography, representing a cleavage fracture mode. FCC-Cu, BCC-V, and β-Ti were detected on both fracture surfaces of the TC4 titanium alloy and T2 pure copper sides. The influence of welding temperature on the diffusion of V in Ti was greater than on Ti in V, and Ti and Cu diffused faster than V in the joint.

The influence of parameters of linear flat bottom chip breaker on chip flow

The simulation model of cutting TC4 titanium alloy with a YG8 cemented carbide tool is established through ABAQUS. The minimum width of the chip breaker, anti-chip surface angle, bevel angle of chip breaker, and the change of chip breaker front angle at the tooltip are changed by controlling other chip breaker parameters unchanged. Orthogonal tests are established under different edge angles to analyze the influence of the relevant parameters of the chip breaker on the chip angle and the influence of the change of the chip breaker parameters on the chip angle under different inclination angles. The results show that the chip breaker parameters affect the chip flow direction. The larger the groove spacing is, the smaller the chip flow angle first decreases and then becomes stable. The chip flow angle increases with the increase of the anti-chip surface angle, bevel angle of the chip breaker, and chip breaker front angle. The larger the inclination angle is, the more obvious the influence of chip breaker parameters is.

Comparison of mechanical properties of interbody fusion cage with three general structures

Lumbar interbody fusion cage has been widely used in the treatment of various clinical lumbar diseases, and the mechanical properties of the lumbar interbody fusion apparatus are very important to the initial stability after implantation. According to the development trend of interbody fusion cages, this work designed three bullet-type interbody fusion cages, which are window-type, windowless and fenestrated type. Three groups of experimental samples were formed by using TC4 titanium alloy material and an SLM forming process (laser power 170 W, scanning speed 1150 mm/s). After post-processing, the mechanical properties of the three different structures were compared and analyzed through static and dynamic fatigue experiments. The tissue defects before and after the fatigue test were observed by CT. It was concluded that the fenestrated interbody fusion cage has better comprehensive mechanical properties and is relatively safer.

Study on the Laser Melting Procedure for the Specified Zone of the TC4 Titanium Alloy

This paper presents an in-depth study of the variable reference process to improve the organization and properties of selective laser melting TC4 specimens. A relationship equation between body energy density and stratification is proposed. This study aimed to look into how layer and volume energy density affect the surface, tensile characteristics, and microstructure of specimens. The test findings demonstrated that specimen densities rise as the power index falls, with the most excellent density reaching 99.42%. The number of secondary α’ phases declined as the energy density of the laminae slowed down. The tensile strength of these specimens reached 1190.84 MPa, and the yield strength came at 1103.87 MPa with the same interval of variable laser power. This offers a fresh avenue for research into SLM to enhance the specimens’ overall performance.

Microstructure and Mechanical Properties of TC4 Titanium Alloy at the Temperature of 77K

Titanium alloy has the advantages of low thermal conductivity, a small expansion coefficient and being non-magnetic, making it an ideal low-temperature structural material. In this paper, the typical TC4 titanium alloy in industrial titanium alloy is selected as the research object. The microstructure deformation law and mechanical behavior of TC4 titanium alloy at liquid nitrogen temperature are mainly investigated, and compared with the microstructure and properties at room temperature. The macroscopic and microscopic deformation mechanism of the simultaneous increase in elongation and hardening index of titanium alloy at low temperature is revealed, which provides a basic basis for the low-temperature deformation mechanism and strengthening and toughening design of titanium alloy. Based on the uniaxial tensile tests at room temperature (298 K) and low temperature (77 K), the effects of low temperature on the yield strength, elongation, tensile strength and work hardening curve of titanium alloy were compared and analyzed. The strength/plasticity synergistic improvement of TC4 titanium alloy under low-temperature deformation was found. At low temperature, the yield strength, tensile strength and elongation of TC4 titanium alloy are improved compared with room temperature. The tensile strength increases from 847.93 MPa at 298 K to 1318.70 MPa at 77 K, and the elongation increases from 21.8% at 298 K to 24.9% at 77 K. The grain morphology, grain orientation, dislocation density and fracture morphology of titanium alloy under room temperature and low-temperature tensile conditions were studied by SEM and EBSD. The results of fracture morphology characterization at room temperature and low temperature show that TC4 titanium alloy exhibits ductile fracture characteristics and a large number of dimples are formed on the fracture surface. The dimple depth at low temperature is shallower than that at room temperature and the overall surface is more flat. Compared with room temperature deformation, the deformation process of TC4 titanium alloy in a low-temperature environment produces stronger dislocation pile-up and forms a large number of twins, but the grain rotation is more significant, which effectively alleviates the stress concentration and delays the initiation and propagation of cracks at grain boundaries.

Study of electrical pulse heat assisted cutting of titanium alloy TC21 based on the finite element method

Titanium alloys are widely used in various fields because of their high strength, excellent corrosion resistance, and high heat resistance. As a new advanced titanium alloy for aviation, TC21 titanium alloy has high strength and poor machinability. It is of great significance to study the cutting mechanism of this alloy and the methods to improve the machinability of aircraft. In this paper, aiming at the difficult machinability of titanium alloy TC21, EPH online heating assisted cutting method is put forward for the first time. During the cutting experiment, the TC21 alloy sample was heated to a variety of temperatures through the electric pulse thermal heat technique. Chip shape and cutting force under different heating temperatures were obtained by cutting experiments. In order to study the influence of the heat-assisted cutting process on the machining of TC21 alloy, the orthogonal finite element model was proposed to simulate the heat-assisted cutting process of TC21 alloy. Through this simulation, chip formation, cutting force, and cutting temperature variation were all obtained. The chip formed by the simulation was in accordance with the actual chip. The results demonstrate that the influence of heat-assisted machining on chip morphology of titanium alloy is relatively small, but it has a significant influence on cutting force and surface roughness. The results show that when the sample is heated to 600°C, the surface quality is the best and cutting force can be reduced by more than 40%.

Investigation on the influence of laser peening on the erosion wear properties in TC21 titanium alloy

The study on improving the erosion wear resistance of TC21 titanium alloy through laser peening (LP) was carried out. The residual stress and full width half maximum (FWHM) in the gradient direction of the specimens before and after LP was analyzed, while the in-depth microhardness was also tested. The microstructural response generated by LP was observed using electron backscattered diffraction (EBSD). The erosion wear properties of differently processed specimens were finally trialed. The results indicated that LP effectively enhanced the erosion wear resistance of TC21 titanium alloy by generating grain refinement and compressive residual stress (CRS) without much deterioration of the surface roughness.

Electrochemical Corrosion Behavior of Ti-N-O Modified Layer on the TC4 Titanium Alloy Prepared by Hollow Cathodic Plasma Source Oxynitriding

TC4 alloy is widely used in dental implantation due to its excellent biocompatibility and low density. However, it is necessary to further improve the corrosion resistance and surface hardness of the titanium alloy to prevent surface damage that could result in the release of metal ions into the oral cavity, potentially affecting oral health. In this study, Ti-N-O layers were fabricated on the surface of TC4 alloy using a two-step hollow cathode plasma source oxynitriding technique. This resulted in the formation of TiN, Ti2N, TiO2, and nitrogen-stabilized α(N)-Ti phases on the TC4 alloy, forming a Ti-N-O modified layer. The microhardness of the samples treated with plasma oxynitriding (PNO) was found to be 300–400% higher than that of untreated (UN) samples. The experimental conditions were set at 520 °C, and the corrosion current density of the PNO sample was measured to be 7.65 × 10−8 A/cm2, which is two orders of magnitude lower than that of the UN sample. This indicates that the PNO-treated TC4 alloy exhibited significantly improved corrosion resistance in the artificial saliva solutions.

Analysis and Optimization of Milling Deformations of TC4 Alloy Thin-Walled Parts Based on Finite Element Simulations

TC4 (DIN3.7164/5) alloy thin-walled parts are widely used in aviation and aerospace industries. However, due to their special structure, shape and poor machinability, large milling forces and milling deformation often occur in the milling process, which cannot guarantee the machining quality and accuracy. The milling processing parameters and milling geometric parameters have a significant impact on the milling force and the deformation, and optimization of the influence factors of milling deformations is important for milling quality. Considering that performing milling experiments under multiple conditions is often costly and time-consuming, this paper provides a finite-element-simulation-based method to study effects of the factors on the forces and deformations during milling thin-walled parts. Firstly, using ABAQUS, a finite element simulation model of the milling process of thin-walled parts is established. Additionally, an orthogonal experimental scheme is designed for optimization of the milling parameters, so as to determine the optimized experimental scheme, and then the optimized experimental scheme is verified to reduce the milling force and deformation by finite element simulations. The optimal parameters for a minimal milling force are a spindle speed of 2000 r/min, a feed rate per tooth of 0.04 mm/z, a milling depth of 1.6 mm, a milling width of 1 mm, a diameter of 6 mm, a rake angle of 20°, a tilt angle of 45°, and two teeth. Similarly, the optimal parameters for minimal node deformations are a spindle speed of 4800 r/min, a feed rate per tooth of 0.18 mm/z, a milling depth of 1 mm, a milling width of 1 mm, a diameter of 16 mm, a rake angle of 20°, a tilt angle of 40°, and four teeth. In addition, this paper uses an optimization algorithm to fit the empirical function with a certain practical value, which can provide a reference for the machining of TC4 titanium alloy. By doing so, we can optimize the milling parameters to obtain the desired machining quality and accuracy, while also saving on time and resources.

Three-Layered Thin Films for Simultaneous Infrared Camouflage and Radiative Cooling.

With the rapid advancements in aerospace technology and infrared detection technology, there are increasing needs for materials with simultaneous infrared camouflage and radiative cooling capabilities. In this study, a three-layered Ge/Ag/Si thin film structure on a titanium alloy TC4 substrate (a widely used skin material for spacecraft) is designed and optimized to achieve such spectral compatibility by combining the transfer matrix method and the genetic algorithm. The structure exhibits a low average emissivity of 0.11 in the atmospheric windows of 3-5 μm and 8-14 μm for infrared camouflage and a high average emissivity of 0.69 in 5-8 μm for radiative cooling. Furthermore, the designed metasurface shows a high degree of robustness regarding the polarization and incidence angle of the incoming electromagnetic wave. The underlying mechanisms allowing for the spectral compatibility of the metasurface can be elucidated as follows: the top Ge layer selectively transmits electromagnetic waves ranging from 5-8 μm while it reflects those in the ranges of 3-5 μm and 8-14 μm. The transmitted electromagnetic waves from the Ge layer are first absorbed by the Ag layer and then localized in the Fabry-Perot resonance cavity formed by Ag layer, Si layer and TC4 substrate. Ag and TC4 make further intrinsic absorptions during the multiple reflections of the localized electromagnetic waves.

Study on ballistic performance of a spherical cylindrical ceramic armor structure

A new type of ceramic armor structure is designed by using spherical cylindrical ceramic splice plate as panel with metal steel frame applied, TC4 titanium alloy and 685 steel as back plate respectively in this paper. Ballistic test of spherical cylindrical ceramic armor structure was carried out by firing 14.5mm penetrator projectile with 14.5mm ballistic gun. Results show that: damage area of spherical cylindrical ceramic armor is smaller when the weight is lighter and the aftereffect damage is similar, and ballistic performance of spherical cylindrical ceramic armor structure is better than that of conventional ceramic composite structure, which has certain advantages in anti-multiple projectile capability; ballistic performance of armor structure with TC4 titanium alloy as back plate is better than that with 685 steel as back plate when area density is the same. Therefore, using spherical cylindrical ceramics can reduce influence of the edge area on ballistic performance of armor structure, making protective capacity of the whole armor structure plate tend to be consistent, and improve anti-multiple resistance of armor structure furtherly.

Effect of bolt tightening torque on fatigue life of multi-bolted composite structure

Bolt tightening torque has an influence on the fatigue life of the multi-bolted joints which cannot be ignored, but there are few methods to predict the fatigue life of the multi-bolted composite structure by considering the bolt tightening torque. A fatigue life prediction method of the multi-bolted composite structure by considering the bolt tightening torque is proposed. It can take into account the various damages of bolts and laminates and accurately calculate fatigue life and damage evolution of multi-bolted composite structure. The multi-bolted composite structure being composed of T300/BMP-316 composite laminates and TC4 titanium alloy bolts is used to verify the present method. The logarithmic error between the predicted fatigue life and the experimental is 4.36%, and the failure mode is consistent with the experimental. Through the present method, the influence of the bolt tightening torque is explored, in which it is found that with the increasing of bolt tightening torque, the fatigue life increases firstly and decreases, and there is an optimal tightening torque. By observing the damage evolution diagram, it is found that when the tightening torque is below the optimal tightening torque, the damage propagation cannot be effectively restrained, which will lead to the reduction of fatigue life. On the contrary, when the tightening torque is more than the optimal tightening torque, it will cause the initial damage to the test piece, which will also lead to the reduction of fatigue life. In engineering, to choose the best tightening torque of the structure for assembly can effectively improve the fatigue life of the structure.

Surface modification improving the biological activity and osteogenic ability of 3D printing porous dental implants

Objective: To explore the mechanical properties, biological activity, and osteogenic ability of 3D printed TC4 titanium (Ti) alloy dental implants treated with surface modification.Methods: Dental implants with 30% porosity were manufactured using selective laser melting (SLM) technology (group 3D), while traditional numerically-controlled machine tools (CNC) were used to manufacture implants without porosity (group SL). The implants were then surface modified through sandblasting and acid etching (groups 3DA1 and SLA1), and then alkali etching (groups 3DA2 and SLA2). The physicochemical properties of the implants were measured using a Vickers hardness instrument, scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), and profilograph before and after surface modification. Next, the biocompatibility, bioactivity, and osteogenic ability of the implants were evaluated using apatite deposition experiments, alkaline phosphatase (ALP) activity, and semiquantitative analysis of extracellular matrix mineralization.Results: There were significant differences in morphology, geometric accuracy, mechanical properties, surface roughness, and hydrophilicity between groups 3D and SL. Furthermore, surface modification improved the physicochemical properties of the porous implants. Implants with sandblasting, acid etching, and alkali etching demonstrated better biocompatibility, bioactivity, and osteogenic ability than implants without surface modification in both groups 3D and SL. Additionally, the implants of groups 3D have higher bioactivity than that of groups SL.Conclusion: Surface modification and the macroporous structure of implants can improve their bioactivity and osteogenic ability, enhancing the application of Ti alloy dental implants.

Combustion Behavior and Microstructure of TC17 Titanium Alloy under Oxygen-Enriched Atmosphere

TC17 titanium alloy is widely used in the aerospace industry, but its combustion behavior and microstructure after combustion are rarely investigated. Herein, the ignition critical oxygen pressure, combustion velocity, and microstructure after the combustion of TC17 titanium alloy were investigated by promoted ignition combustion tests under an oxygen-enriched environment. The results indicated that there were three stages, ignition, splash, and flame propagation, for the combustion process of the TC17 alloy. As compared to TC11 titanium alloy, the TC17 titanium alloy exhibited a similar ignition critical oxygen pressure with the same size, but an obviously faster burning rate, which followed a power law relationship with the oxygen pressure. The segregation of Cr, Mo, and Al was observed in the interdendritic phase of the melting zone and the interface between the melting zone and the heat-affected zone. The segregation of Cr at the liquid/solid interface can be responsible for accelerating the burning kinetic of the TC17 alloy by decreasing the interfacial temperature.

Optimizing Processing Parameters and Surface Quality of TC18 via Ultrasonic-Assisted Milling (UAM): An Experimental Study.

This study conducted longitudinal ultrasonic-assisted milling (UAM) tests and optimized a combination of milling technological parameters to achieve high-quality machining of TC18 titanium alloy. The motion paths of the cutter under the coupled superposition states of longitudinal ultrasonic vibration and end milling were analyzed. Based on the orthogonal test, the cutting forces, cutting temperatures, residual stresses, and surface topographical patterns of TC18 specimens under different UAM conditions (cutting speeds, feeds per tooth, cutting depths, and ultrasonic vibration amplitudes) were examined. The differences between ordinary milling and UAM in terms of machining performance were compared. Using UAM, numerous characteristics (including variable cutting thickness in the cutting area, variable cutting front angles of the tool, and the lifting of the cuttings by the tool) were optimized, reducing the average cutting force in all directions, lowering the cutting temperature, increasing the surface residual compressive stress, and significantly improving the surface morphology. Finally, fish scale bionic microtextures with clear, uniform, and regular patterns were formed on the machined surface. High-frequency vibration can improve material removal convenience, thus reducing surface roughness. The introduction of longitudinal ultrasonic vibration to the end milling process can overcome the limitations of traditional processing. The optimal combination of UAM parameters for titanium alloy machining was determined through the end milling orthogonal test with compound ultrasonic vibration, which significantly improved the surface quality of TC18 workpieces. This study provides insightful reference data for subsequent machining process optimization.