Titanium Alloy Research Articles

The silicide precipitation mechanism and spheroidization behavior of αp phase in a novel near-β titanium alloy during isothermal multi-directional forging process

The tread-off between the strength and ductility of near-β titanium alloys has significantly limited their applications. In this study, a novel near-β titanium alloy containing Si element was designed, and the influence of α-phase spheroidization and silicide precipitation on the mechanical properties was investigated during isothermal multi-directional forging (IMDF) process. The results showed that the β grain is easy to deform and elongate, and the deformed alloy mainly undergoes dynamic recovery (DRV) rather than dynamic recrystallization (DRX). Some silicides are dissolved due to the temperature rise caused by IMDF and the diffusion of atoms on the top of the irregularly shaped silicides. Zr and Si elements are redistributed and segregated at the dislocation, resulting in the formation of submicron-scale and nano-scale silicides. Lath-like αp phase will precipitate from the prior β grain after heat treatment in the dual-phase region, and the volume fraction of αp phase increases with the decrease of heat treatment temperature. In addition, rotation deformation and spheroidization of the lath-like αp phase occur during multi-pass IMDF in the dual-phase region. When multi-pass IMDF temperature is 770 ℃, the silicide distribution is uniform, and the αp phases are equiaxed, which is conducive to the improvement of ductility. The obtained results provide a new way to prepare the Si-containing near-β titanium alloys with excellent mechanical properties.

Simple formula learned via machine learning for creep rupture life prediction of high-temperature titanium alloys

Simple formula learned via machine learning for creep rupture life prediction of high-temperature titanium alloys

Prediction of grain size in TB18 titanium alloy forgings by re-crystallization and grain growth modelling

Prediction of grain size in TB18 titanium alloy forgings by re-crystallization and grain growth modelling

In Situ Rapid Preparation of the Cu-MOF Film on Titanium Alloys at Low Temperature.

Titanium alloys are widely used in marine environments and medical fields due to their excellent corrosion resistance and high specific strength. However, their good biocompatibility can lead to severe biofouling, thereby limiting their effectiveness. To inhibit biofouling on the surface of titanium alloys, this study proposes an antifouling solution, which involves the in situ preparation of Cu-MOF film on titanium alloys by leveraging the antibacterial properties of Cu ions. Here, the dense and stable TiO2 film on the surface of Ti-6Al-4V titanium alloy was removed by alkali-heat treatment; meanwhile, a porous surface structure was simultaneously obtained where OH- ions were retained. In the subsequent step, the retained OH- ions in the pores attracted Cu2+ ions in solution to form Cu(OH)2 in the pores, providing active sites for the formation of Cu-MOFs. Subsequently, Cu(OH)2 reacted with organic ligand (1,3,5-benzenetricarboxylic acid, BTC) at room temperature to form Cu-MOFs in the pores, which then grew quickly to cover the alkali-heat-treated surface within 1 h. The formation mechanism of Cu-MOF film on Ti-6Al-4V was elucidated, which provides a reference for designing and preparing multifunctional MOF film in situ on titanium alloys. The stability of in situ-grown Cu-MOF samples and their inhibitory effects on bacteria and microalgae have also been verified. The results indicate that although the stability of Cu-MOFs is relatively poor, their bactericidal and algicidal effects are extremely significant, suggesting that this material has significant potential for short-term applications that require high antibacterial performance.

Experimental Investigation of the Micro-Milling of Additively Manufactured Titanium Alloys: Selective Laser Melting and Wrought Ti6Al4V

In recent years, additive manufacturing (AM) has gained popularity in the aerospace, automobile, and medical industries due to its ability to produce complex profiles with minimal tolerances. Micro-milling is recommended for machining AM-based parts to improve surface quality and form accuracy. Therefore, the machinability of a titanium alloy (Ti6Al4V) manufactured using selective laser melting (SLM) is explored and compared to that of wrought Ti6Al4V in micro-milling. The experimental results reveal the surface topology, chip morphology, burr formation, and tool wear characteristics of both samples. The micro-milling of AM-based Ti6Al4V generates a surface roughness of 19.2 nm, which is 13.9% lower than that of wrought workpieces, and this component exhibits less tool wear. SLM-based Ti6Al4V produces continuous chips, while wrought Ti6Al4V yields relatively short chips. Additionally, SLM-fabricated Ti6Al4V exhibits smaller burrs after micro-milling than wrought Ti6Al4V. Despite the higher hardness of SLM-based Ti6Al4V, it demonstrates better machinability than wrought Ti6Al4V, resulting in better surface quality with lower tool wear levels and shorter burr heights. This study provides valuable insights into future research on postprocessing AM-based titanium parts, especially using micro-milling.

Comprehensive review of biological response, alloy design, strengthening mechanisms, performance evaluation, and surface modifications of titanium alloys for biomedical applications

Comprehensive review of biological response, alloy design, strengthening mechanisms, performance evaluation, and surface modifications of titanium alloys for biomedical applications

Uncoupled ductile fracture criterion motivated by micromechanisms: Modeling and experiments

Ductile fracture behavior of metallic materials is significantly influenced by the stress states, especially for geometrically complex structures fabricated by laser additive manufacturing (AM) technique. This study proposes a new uncoupled ductile fracture criterion (DFC) that considers void evolution behaviors to predict the ductile fracture of AMed Ti-6Al-4V alloy. The new criterion is derived by synthetically taking into account the effects of stress triaxiality and the Lode parameter on microscopic void evolution behaviors, including void nucleation, growth, and coalescence, which eventually leads to the macroscopic ductile fracture. By comparison with the representative uncoupled ductile fracture criteria, the predictive ability of the proposed criterion for different metallic material is comprehensively discussed through a series of fracture experimental data published in the literature to verify the effectiveness and accuracy of the new criterion. The comparative studies indicate that the new uncoupled ductile fracture criterion can accurately predict fracture strain under different stress states. Particularly, the proposed micromechanism-motivated criterion demonstrates the distinguished effectiveness in predicting ductile fracture under high stress triaxiality compared to other criteria. Furthermore, fracture experiments of additively manufactured titanium alloy were conducted under various stress states to calibrate the material parameters of the proposed criterion. It can be found that the predicted fracture locus of AMed titanium alloy is more dependent on stress state and is generally lower than that of cast titanium alloy produced by traditional processing technology.

Nonuniformity of Fatigue Properties of Two‐Sided Electron Beam Welded Joint of Superthick Titanium Alloy

ABSTRACTThe TC4 titanium (Ti) alloy has been widely utilized in various industries such as aerospace and shipbuilding, owing to its numerous advantages. Its exceptional properties have made it a material of choice for applications requiring high performance and reliability. The total weld thickness was 140 mm, and microstructures and high‐cycle fatigue properties were investigated at three different layers within the 140‐mm section. Experimental results show that the overlap area at two weld roots has the highest microhardness and largest nonuniformity of the overall joints, so the area is found to have the poorest high‐cycle fatigue properties. The microstructures in every layer of the weld metal of the joints were analyzed to determine the causes of the poor fatigue properties in the overlapping area at the weld roots. Significant amounts of α′ acicular microstructure are present in the weld metal of joints, while the overlap area at weld roots contains more α′ acicular microstructure with a finer size. Compared with other layers, the weld metal and base metal in Layer 2 (overlap area) have the largest microhardness gradient, where the stress concentration is more serious in the fatigue experimental process. Heat dissipation conditions was a critical factor for the inhomogeneity of microstructure and mechanical properties along the thickness direction of 140‐mm double‐sided electron beam welding joint. Fatigue damage (micropore) is formed at β phases in priority, and fatigue cracks propagate via series connection of micropores, indicative of transgranular ductile cracks.

Development and verification of material models in modeling of wave strain hardening and additive synthesis processes

BACKGROUND: The creation of competitive machine parts capable of withstanding standard and increased operational loads is an urgent task in mechanical engineering. Developing additive synthesis technologies together with strengthening technologies make it possible to create such products with high load-bearing capacity. However, to improve the efficiency of these technologies, it is necessary to create theoretical models of the processes taking place. The article presents the results of the first stage of creating complex theoretical models of the combined 3DMP process and wave strain hardening (WSH) required for designing technological processes for manufacturing engine parts and brake systems of automotive equipment. . AIMS: Creation and assessment of the adequacy of material models used in finite element modeling of additive synthesis processes with subsequent hardening. MATERIALS AND METHODS: Theoretical models of the material were created in the ANSYS software package, which allows for multidisciplinary calculations. The experimental data required for preparing the models were obtained by testing tensile samples manufactured using standardized methods. The hardness of materials was studied using a KB 30S automatic hardness tester. The adequacy of additive synthesis modeling was assessed based on the distribution of temperature fields. The adequacy of material models for the VDU process was assessed based on the sizes of individual plastic indentations and the distribution diagrams of the depth and degree of hardening in the surface layer. RESULTS: Theoretical models of the following materials were developed: steel, stainless steel, bronze alloy, titanium alloy, aluminum alloy. The theoretical data obtained from the modeling results have a high level of significance. The studies were conducted for various thermal (in the range from +20ºС to +800ºС) and deformation modes. Graphical results of theoretical and experimental studies allow us to obtain a qualitative assessment of the processes under study with the required accuracy. CONCLUSIONS: As a result of the assessment of the adequacy of the developed models, it was established that the discrepancy between the empirical and theoretical data does not exceed 7.4%. The obtained models of materials are statistically significant and can be correctly applied in further studies.

Growth mechanism and tribological behavior of electroless Ni-P plating with ultrasonic assistance on titanium alloy substrate

The aim of this paper is to study the growth mechanism and tribological behavior of electroless Ni-P plating with ultrasonic assistance on TC4 titanium alloy substrate pretreated by zincating and alkaline pre-plating process. The morphology, composition and structure of zincating, pre-plating and electroless Ni-P plating were studied to analyze its growth mechanism. The tribological behavior of electroless Ni-P plating at room temperature was investigated. The results showed that the electroless Ni-P plating had a typical cauliflower-like morphology and microcrystalline structure characteristic. And the morphology of the Ni-P plating under the action of ultrasonic was uniform, compact and smooth. Compared with the TC4 substrate, the friction coefficient and the wear scar width of the plating were reduced by approximately 35 and 70%, indicating that the Ni-P plating improved the wear resistance of TC4. The wear mechanism of the Ni-P plating was adhesive wear under the dominant of plastic deformation, and slightly abrasive wear, while the wear mechanism of TC4 was dominated by adhesive wear, accompanied by abrasive wear and oxidative wear. The ultrasonic cavitation promoted the elemental interdiffusion between the substrate and Ni-P plating resulting in the formation of the diffusion layer. The ultrasonic cavitation and mass transfer effects improve the activity of the deposition surface and the generation of atomic hydrogen, and promote the nucleation and growth of nickel on the deposition surface, as well as the diffusion of Ni2+ and H2PO2− to the deposition surface. The growth rate of the Ni-P cell-like structures in the parallel direction is greater than in the perpendicular direction. The Ni-P plating grows in a layered manner, and the growth mechanism is the heterogeneous nucleation growth mechanism.

Impact resistance and high-speed dry cutting performance against titanium alloy of AlCrBON coatings with various oxygen contents

In this work, four AlCrBON coatings with various oxygen contents were fabricated. As the oxygen content increased, a phase transition from fcc-(Cr, Al)N to fcc-(Cr, Al)(O, N) occurred, the Al-O and Cr-O bonds increased while Al-N and Cr-N bonds reduced. The AlCrBON coating with a 13.4-atom% oxygen content (C2 coating) exhibited a high nano-hardness (39.6 GPa) and scratch adhesion (with Lc2 of more than 70 N), low high-frequency impact force (0.7 N), less delamination, and more cutting times (10 min under 80 m/min and 240 s under 100 m/min) against titanium alloy under both cutting speeds. Addition of O relieved the wear both on the flank face and rake face of the coated inserts against titanium alloy throughout the cutting process.

TiNbSn alloy plates with low Young's modulus modulates interfragmentary movement and promote osteosynthesis in rat femur

Orthopedic implants such as arthroplasty prostheses, fracture plates, and intramedullary nails often use materials like Ti6Al4V alloy and commercially pure titanium (CP-Ti), which have Young's modulus significantly higher than that of human cortical bone, potentially causing stress shielding and inhibiting effective fracture healing. TiNbSn alloy, a β-type titanium alloy with a lower Young's modulus (40–49 GPa), has shown promise in reducing stress shielding and enhancing bone healing by promoting effective load sharing with bone. This study used 5-hole plates made from TiNbSn alloy and CP-Ti to investigate their effects on bone healing in a rat femoral fracture model. Micro-CT analysis and mechanical testing were performed six weeks postoperatively to assess bone healing. Additionally, Finite element method (FEM) analysis was employed to evaluate stress shielding and interfragmentary movement (IFM) at the fracture site. Micro-CT analysis revealed significantly higher bone volume and mineral density in the TiNbSn group than in the CP-Ti group. Mechanical testing showed increased maximum load and stiffness in the TiNbSn group (77.2 ± 10.0 N for the TiNbSn alloy plate group versus 53.3 ± 8.5 N for the CP-Ti group (p = 0.002)). FEM analysis indicated that TiNbSn plates reduced stress shielding and allowed for greater displacement and strain, promoting IFM conducive to bone healing. The findings suggest that TiNbSn alloy plates are more effective than CP-Ti plates in promoting bone healing by reducing stress shielding and enhancing IFM. The lower Young's modulus of TiNbSn allows better load distribution, facilitating bone regeneration and strengthening at the fracture site.

Nickel–titanium alloy porous scaffolds based on a dominant cellular structure manufactured by laser powder bed fusion have satisfactory osteogenic efficacy

Nickel–titanium (NiTi) alloy is a widely utilized medical shape memory alloy (SMA) known for its excellent shape memory effect and superelasticity. Here, laser powder bed fusion (LPBF) technology was employed to fabricate a porous NiTi alloy scaffold featuring a topologically optimized dominant cellular structure that demonstrates favorable physical and superior biological properties. Utilizing a porous structure topology optimization method informed by the stress state of human bones, two types of cellular structures—compression and torsion—were designed, and porous scaffolds were produced via LPBF. The physical properties of the porous NiTi alloy scaffolds were evaluated to confirm their biocompatibility, while their osteogenic efficacy was investigated through both in vivo and in vitro experiments, with comparisons made against a traditional octahedral unit cell structure. NiTi alloy porous scaffolds can be nearly net-shaped via LPBF and exhibit favorable physical properties, including a low elastic modulus, high hydrophilicity, a specific linear expansion rate, as well as superelastic and shape memory effects. These scaffolds demonstrate excellent biocompatibility, support in vitro osteogenesis, and possess significant in vivo bone ingrowth capabilities. When compared to titanium alloys, NiTi alloys show comparable osteogenic properties in vitro but superior bone ingrowth properties in vivo. Additionally, among octahedral-type, torsion-type, and topologically optimized compression-type porous scaffolds, the latter demonstrates enhanced bone ingrowth properties. LPBF technology is effective for manufacturing porous NiTi alloy scaffolds with fine pore structures and excellent mechanical properties. The scaffolds based on topologically optimized dominant cellular structures facilitate satisfactory and efficient bone formation.

Antifouling Slippery Surface with Enhanced Stability for Marine Applications.

In recent years, slippery liquid-infused porous surfaces (SLIPSs) have gained significant attention in antifouling applications. However, their slippery performance often deteriorates in dynamic environments, limiting their service life. TC4 titanium alloy, commonly used in hulls and propellers, is prone to biofouling. SLIPSs have gained significant attention in antifouling applications. However, their slippery performance often deteriorates in dynamic environments, limiting their service life. To address these issues, a novel slippery liquid-infused surface (STASL) was developed on TC4 through the integration of hydroxyl end-blocked dimethylsiloxane (OH-PDMS), a silane coupling agent (KH550), and nano-titanium dioxide loaded with silver particles (TiO2-Ag, anatase) and silicone oil, thereby ensuring stable performance in both dynamic and static conditions. The as-prepared surfaces exhibited excellent sliding capabilities for water, acidic, alkaline, and saline droplets, achieving speeds of up to 2.859 cm/s. Notably, the STASL demonstrated superior oil retention and slippery stability compared to SLIPS, particularly at increased rotational speeds. With remarkable self-cleaning properties, the STASL significantly reduced the adhesion of proteins (50.0%), bacteria (77.8%), and algae (78.8%) compared to the titanium alloy. With these outstanding properties, the STASL has emerged as a promising solution for mitigating marine biofouling and corrosion on titanium alloys.

Preparation and Properties of Cu-Containing High-entropy Alloy Nitride Films by Magnetron Sputtering on Titanium Alloy

Preparation and Properties of Cu-Containing High-entropy Alloy Nitride Films by Magnetron Sputtering on Titanium Alloy

Multi-objective Optimization of Turning Titanium Alloy by Grey Rational Analysis

In order to optimize the turning operation on titanium alloy, one needs to understand how different parameter combinations serve under varied conditions and needs. It is critical to compare single and multiple objectives in optimization. This study focused on single and multi-objective optimization evaluations for the primary performance responses of surface roughness (SR) and tool flank wear (TW), aiming for optimal turning process parameters. To examine the effects of feed rate (f), cutting speed (R), depth of cut (d), cutting angle (X), and mist inlet pressure (P) on the responses of both SR and TW, Taguchi L27 orthogonal arrays were used in this study. Moreover, analysis of variances (ANOVA) and grey relational analysis (GRA) have been incorporated in this study, where the former was used to study the influence of each parameter on SR and TW while the latter was used to determine the best combinations for the multi-objective optimization process. The results revealed that for single-objective optimization of SR, the optimal values for f, R, d, X, and P were found to be 0.3 mm/rev, 250 rpm, 1.5 mm, 100 degrees, and 1 bar mist inlet pressure, respectively. For single-objective optimization of TW, the optimal values for f, R, d, X, and P were found to be 0.20 mm/rev, 250 rpm, 0.5 mm, 50 degrees, and 3 bar mist inlet pressure, respectively. Meanwhile, for multi-objective optimization, the optimal values for f, R, d, X, and P were found to be 0.30 mm/rev, 500 rpm, 2.0 mm, 75 degrees, and 1 bar mist inlet pressure, respectively. These optimal combinations of turning parameters resulted in the lowest SR and TW simultaneously.

Design Modification and Finite Element Analysis of Stainless Steel 316L Locking Compression Plates for Mid-Transverse Fractures

Bone fracture is the most common orthopedics problem. To achieve stability in the internal fixation of bone fragments, apply a Locking Compression Plate (LCP), which consists of a set of plates and screws. Common materials used for the bone fixation plate are stainless steel, titanium, and other metal alloys. Those materials are stiffer than cortical bone, causing a stress shielding effect. The stress shielding phenomenon takes place during bone remodelling, which affects the growth of bone and bone loss upon the healing process. The purpose of this study is to design the best LCP to minimize or eliminate the stress shielding issue for tibia shaft fracture. A reverse engineering process is used to obtain the solid part using 3D scanning, and data clean-up is done in CATIA V5, which is then used to be imported into the finite element software ANSYS 23R2. The fracture simulation is on transverse type fractures with the creation of a gap of 1 mm around the mid-tibial shaft region. Several boundary conditions will be parametrized, such as material properties, contact definitions, meshing, and loading conditions in preprocessing. This paper examines and simulates the behaviour of LCP under a load via finite element analysis (FEA). Design 2 was selected due to its superior stress distribution,resulting in the LCP bearing only 177.98 MPa with a total deformation of 0.57 mm

Crystal plasticity modeling of fretting fatigue crack initiation behavior in Ti6Al4V

Fretting Fatigue (FF) constitutes a significant concern in engineering applications, notably in components subjected to cyclic loading and relative motion, such as dovetail joints in aircraft engines. In this context, the mechanical behavior of Ti6Al4V, a widely employed titanium alloy distinguished by its exceptional mechanical properties, has critical importance. Despite Ti6Al4V’s commendable strength-to-weight ratio, its susceptibility to FF presents significant challenges to the structural integrity and operational lifespan of crucial components. Consequently, a comprehensive understanding of the mechanical response of Ti6Al4V due fretting conditions and stands imperative for advancing the reliability and lifespan of aerospace structures. Microstructural characteristics, such as grain size and grain orientation, directly influence the material’s macroscopic mechanical response and fatigue life. This study leverages a Crystal Plasticity Finite Element Method (CPFEM) coupled with a sub-modelling technique to systematically investigate FF crack initiation characteristics of Ti6Al4V under various loading conditions. The impacts of dual- phase grains, grain size, and crystal orientation on FF behavior are explored. The study employs the critical plane method to compute Damage Parameters (DPs), aiming to enhance the predictive accuracy of FF life. An isotropic model and three Crystal Plasticity Finite Element (CPFE) models with different grain sizes are compared, focusing on their stress–strain behavior and representation of DPs. The CPFE models, proposed herein, exhibit remarkable precision in forecasting FF crack initiation and is validated against experimental FF data.

Insight into the keyhole behaviour and its role on residual stress formation in vacuum electron beam welding of TC4 titanium alloy

Electron beam welding (EBW) is the preferred technique for joining TC4 titanium alloy. Accurately characterizing the welding keyhole and residual stress distribution, along with analyzing their formation mechanisms, is of paramount importance for ensuring high reliability of the TC4 EBW structures. In this regard, a “thermal-fluid-metallurgical-mechanical” multi-field coupling numerical method was developed, which was then validated by the vital experiments. The evolution of the keyhole, molten pool temperature, phase volume fraction and residual stresses was then revealed. The influencing mechanism of keyhole on residual stress was explored comprehensively. The results show that metal vapor recoil pressure serves as the primary factor in keyhole formation, while the surface tension promotes keyhole closure. The β-phase in the weld zone undergoes a complete transformation into α′ acicular martensite. Moreover, the maximum longitudinal stress occurs at the weld center, while the transverse stress exhibits a substantial stress gradient along the thickness direction. Increasing the welding power raises the temperature of molten pool. The keyhole depth and width are also enlarged, accompanying by the increase of residual stress, which is expected to offer a theoretical foundation for managing the keyhole and residual stress generated during the EBW of TC4 titanium alloy.

Influence of material orientation, loading angle, and single-shot repetition of laser shock peening on surface roughness properties

Titanium alloy Ti6Al4V is extensively utilized in biomedical applications due to its excellent biocompatibility, corrosion resistance, and mechanical properties. The design of dental implant surface textures has changed throughout time to address issues with oral rehabilitation in both healthy and damaged bones. The longevity of an implant is significantly impacted by surface roughness. This study examines the use of laser shock peening (LSP) as a surface modification technique to improve the mechanical properties of implants. A numerical model is developed using the commercial finite elements software in ABAQUS/Explicit for simulating dynamic conditions. The aim of the study is to develop surface roughness parameters using computational methods such as studies have not yet been contemplated. The single shot angle, shot repeat, time, material orientation, and laser power are applied for the first time simultaneously to evaluate the impact of material orientation and loading angles on surface roughness parameters. The study showed that the developed computational model’s compressive residual stress was −578.45 MPa, while the experimental samples were −592.18 MPa. Consequently, the difference between the computational and experimental results was 2.32%. Without regard to material orientation or angle, the compressive residual stress of the samples under examination was found to be −578.450 MPa after three repetitions and to decreased to −1.620 MPa after four. These results demonstrate that by varying the material orientation and loading angle, the Ra value may be increased four times.