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Titanium alloy is difficult to machining in the conventional machining process. Hybrid production technology for abrasive water jet machining (AWJM) allows the machining of all engineering applications. This paper explores the optimization of the process variables of Titanium alloy AWJM (Ti- 6Al- 2Sn- 4Zr- 2Mo). The AWJM process parameters such as water jet strength, traverse speed, and standoff distance were studied against the material removal rate, surface roughness, kerf angle. The contribution of this parameter to responses has been calculated by variance analysis. For material removal rate, surface roughness, kerf angle, regression models were obtained.

In this work, the main aim is to reduce the adhesion and wear that happened during machining of the Ti6Al4V alloy by employing volcano-like texture on the rake face of coated tool. A combination of experimental and simulative investigation was adopted. DEFORM-3D software with updated Lagrangian formulation was used for numerical simulation, and the thermo-mechanical analysis was performed using Johnson-Cook material model to predict the cutting temperature, cutting forces, chip morphology and tool wear. In cutting experiments, volcano-like textures with different area densities (10%, 20%, 30%) were fabricated by fiber laser on the rake face of cemented carbide tools close to the main cutting edge. Then, these textured tools were deposited with CrAlN coating through cathodic vacuum arc ion plating technique. Experiments in cutting Ti6Al4V alloy were carried out with the textured coated tools and non-textured coated tool under dry and wet cutting conditions. Then, the chip morphology, chip size and tool wear were investigated. The results showed that textured coated tools were superior to conventional tool. Especially in wet cutting, compared with those of non-textured coated tool, the adhesion area and the chip curling radius of the coated tool with texture area density of 20% (VCT2) were reduced by 31.2% and 49.7%, respectively. Therefore, VCT2 tool showed a better cutting performance. Finally, the mechanisms of textured coated tools under dry and wet cutting conditions were proposed.

The paper describes the results of fatigue and corrosion-fatigue tests of the pseudo α titanium alloy PT-3V, which is actively used in nuclear engineering for the manufacture of heat exchange equipment for modern nuclear power plants. Alloy PT-3V has an inhomogeneous coarse-crystalline structure with precipitates of β-phase particles along the grain boundaries of the lamellar shape. It is shown that smooth specimens tested according to the bending-with-rotation loading scheme do not show a noticeable decrease in the cyclic fatigue life when exposed to a neutral corrosive environment (3 % aqueous NaCl solution). However, specimens with a notch (stress concentrator) tested according to the cantilever bending loading scheme demonstrate sensitivity to the action of a corrosive environment at the stages of initiation and growth of fatigue cracks, as evidenced by a significant decrease in the number of cycles before crack initiation, as well as before specimen failure, in comparison with tests in air. Fractographic analysis of fractures of smooth specimens and specimens with a concentrator after fatigue and corrosion-fatigue tests has been carried out. The main stages of the initiation and growth of fatigue cracks are revealed. It has been established that a decrease in the resistance to the initiation and propagation of corrosion-fatigue cracks during testing of notched specimens may be due to the effect of hydrogen embrittlement, accelerated by stress concentration.

The investigate about the effect of the microstructure of Ti6Al4V alloy on its cavitation erosion and corrosion properties in marine can provide the key basis for the application. On the basis of as-received Ti6Al4V(TC4) alloy, FC-TC4 and AC-TC4 alloys were prepared by heat treatment with the cooling method of a furnace and atmospheric environment, respectively. Then the microstructure evolutions of three samples were scrutinized and the effect of microstructure on their cavitation erosion and corrosion resistance was explored. The results showed that more recrystallized grains formed as well as its content of α grains and high-angle grain boundaries increased in AC-TC4 alloy. To FC-TC4 alloy, there was obvious grain growth apart from recrystallization. Moreover, many nanotwins of TiV and TiAl3 were formed separately in FC-TC4 and AC-TC4 alloys due to the dislocation migration during heat treatment. The microstructure evolution led the hardness and elastic modulus of AC-TC4 alloy were the best, followed by FC-TC4 alloy, that of TC4 were the worst. Similarly, passivating ability of AC-TC4 alloy was the best among three samples because of its microstructure. Although cracks extended along the grain boundaries under the action of continual cavitation erosion, the passivation film formed by TiO2 and Al2O3 would enhance their resistance to further corrosion and cavitation erosion in artificial seawater.

Generally, off-line methods are used for surface roughness prediction of titanium alloy milling. However, studies show that these methods have poor prediction accuracy. In order to resolve this shortcoming, a prediction method based on Cloudera's Distribution Including Apache Hadoop (CDH) platform is proposed in the present study. In this regard, data analysis and process platform is designed based on the CDH, which can upload, calculate and store data in real-time. Then this platform is combined with the Harris hawk optimization (HHO) algorithm and pattern search strategy, and an improved hybrid optimization (IHHO) method is proposed accordingly. Then this method is applied to optimize the SVM algorithm and predict the surface roughness in the CDH platform. The obtained results show that the prediction accuracy of IHHO method reaches 95%, which is higher than the conventional methods of SVM, BAT-SVM, GWO-SVM and WOA-SVM.

In this paper, the effect of rare earth oxide additive on coating material deposited by laser cladding process on various engineering materials has been discussed. The purpose of rare earth oxide additive in the coating composition is to improve the various properties like mechanical, tribological, and chemical properties. The main rare earth oxides are La2O3, CeO2 and Y2O3, which are generally used in laser cladded coatings. The limited amount of addition of these rare earth oxide compound may leads to improvement in hardness, wear and corrosion resistance of coating. The attractive properties of rare earth oxide is grain refinement, conversion of coarse structure to fine dendritic structure, creating grain boundary movement hindrance of dislocation in the material which leads to its application as nutrients in the coating material. The main purpose of coating is to enhance the surface properties of material like hardness, corrosion resistance and wear resistance. When rare earth oxide are added to the coating then it creates extra enhancement in the above properties. The laser cladding is widely used in modern manufacturing technology due to its very attractive properties like good metallurgical bonding with substrate, less dilution, minimum distortion, less heat affected zone and fast solidification and high cooling rate. In this review article the coating developed by laser cladding on various conventional engineering materials like ferrous materials, magnesium alloys, titanium alloys, aluminium alloys and nickel based super alloys with rare earth oxide addition are described.

This paper discusses about the recent advancements in laser cladding and alloying processes used for surface property enhancement of magnesium and its alloys. Laser cladding and alloying is advanced manufacturing method used for surface modification of metallic materials in the modern industries. The cladding process is surface modification technique, which is used for deposition of thick layer of advanced materials on surface of conventional materials to improve the surface properties like, wear resistance, hardness, oxidation resistance, corrosion resistance, biocompatibility and heat resistance. The advanced materials generally used for cladding operations are transition metals, alloys, ceramics, composites, nanomaterials, rare earth oxide and some solid lubricant additives. The conventional substrate materials are steel, cast iron, titanium alloy, aluminium alloy, magnesium alloys and copper alloys. Laser cladding is most widely used coating technique because of its attractive properties such as low dilution rate, good metallurgical bonding between coating and substrate, less distortion, narrow heat affected zone, high solidification and cooling rate. In this article magnesium alloy is considered as substrate material and the various coating materials used for its surface modification are explained. Also, the effects of various laser process parameters on phase composition, microstructure, elemental composition, mechanical properties, tribological properties and corrosion resistance are discussed. The characterization techniques such as XRD, SEM, EDS, Vickers microhardness test, wear and friction test, corrosion test used for coating analysis are described. Furthermore, the problem arises in laser cladding and alloying on magnesium alloy and their possible remedies are discussed.

Selective laser melting [SLM] is an additive manufacturing process for metals and alloys. In this paper, mechanical properties of Titanium based alloys prepared by SLM, are reviewed based on the recent (2019–2021) research works on the same. Basic process of SLM is explained with a diagram. The effect of process parameters on properties are compared and analysed. Enhancements in properties like tensile strength, yield strength, ductility and hardness are discussed with relevant data. With available works, a study of post heat treatment of SLM Ti alloys are also conducted.

Titanium and its alloys have become the ultimate choice for the next era of orthopedic implants such as Hip stem, acetabular cup, and orthopedic accessories. This critical review presents the challenges in fabrication and solutions (surface engineering) to successfully implement Ti alloys in biomedical industries successfully. A critical review on the application surface modification of Ti-alloy using thermal spray coatings has been reported. Hydroxyapatite (HA) has been used as vital biological coating-materials for load-bearing implant applications, mostly hip implants. Moreover, the research papers also present bibliometric analysis that reveals the researcher's information and their affiliation for significant contribution in the area of Ha-coatings on Ti-alloy using plasma spray techniques.

To improve productivity and quality of machining process using Electrical Dischagre Machining (EDM), a lot of electrodes such as coated and alloy electrodes has been applied. Study on multi-objects optimization in EDM with coated electrode will increase number of application of this field into practice. In this study, material removal rate (MRR) and surface roughness (SR) in Electrical Dischagre Machining using Niken coated aluminium electrode were optimized simultaneously using Taguchi - AHP – Topsis methods. Technological parameters including Peak Current (I), Gap Voltage (U) and pulse on time (Ton) were investigated. Titanium alloy (Ti-6Al-4V) was selected as workpiece in experimental process. The results show that combination among Taguchi - AHP - Topsis methods is suitable to solve multi-objects optimization in EDM. The optimized technological parameters are I = 30A, Ton = 500 µs, U = 50 V and optimized quality criterias are MRR = 0.17 mm3/min and SR = 8.76 µm.

Titanium and titanium alloys are widely spread in biomedical applications. The need to replace high-cost alloying elements is increasing, as well as the low biocompatibility elements. In the current study, the microstructure, mechanical properties, corrosion resistance, and cytocompatibility of the new biomedical Ti–14Mn–xZr alloys were investigated (x = 1.5, 3, and 6% wt. Zr). Homogenization, solution heat treatments, and cold deformation were applied. The results showed the predominance of the β-phase even after a high degree of deformation. The mechanical properties showed that Ti–14Mn–xZr have ultra-high-strength values that reach 1830 MPa with low elongation. Furthermore, the severe deformation by cold rolling and increasing the Zr content enhances the corrosion resistance of Ti–14Mn–xZr alloys. The cytotoxicity test shows that Ti–14Mn–xZr alloys have very high cytocompatibility with cell viability within 96 ≈ 99%, representing a potential alloy that can be considered for further development of bio-applications.

When dealing with post-processing steps of additively manufactured parts, the issue of the surface finishing of freeform surfaces has to be addressed. The flexibility of ball end milling makes this machining operation particularly suitable to finish such parts. However, literature records dealing with this kind of cutting operation on additively manufactured alloys are very scarce. The microstructural anisotropy induced by the additive manufacturing process may influence the machinability of a metal alloy such produced, distinguishing it from the same alloy conventionally fabricated. At present, there is no thorough understanding of the influence of additively built component anisotropy on ball end milling operations, resulting in the unpredictability of the part behavior once machined. In this work, ball end milling was carried out on both additively and conventionally manufactured Ti6Al4V alloy workpieces characterized by an inclination angle of 15°, 45°, and 75°. For the first time, the impact of the peculiar microstructural features induced by additive manufacturing was studied in ball end milling operations with different tool paths orientations. The interpretation of the results was helped by the comparison with the wrought alloy. The machinability was assessed in terms of cutting forces, surface topography, surface defects, and chip morphology. The results demonstrated that the additively manufactured alloy allowed for better machinability than the wrought one only when the cutting edge was parallel to the α phase colonies within the prior β grains, thus favoring the material removal by locally decreasing the material resistance to cutting.

Titanium alloys are difficult-to-cut materials and difficult to be lubricated. In this paper, a new synthetic water-based cutting fluid for titanium alloys is developed. The main ingredients which contain polar groups are easy to adsorb on titanium alloy and form a stable boundary lubricant film. The lubricating and anti-wear properties of the developed cutting fluid were tested and the results show that the use of the developed cutting fluid leads to a low friction coefficient. Moreover, the machining performance of the developed cutting fluid was further tested through tapping, milling, and drilling. The tapping torque, machining force, tool wear, and machined surface roughness were used to evaluate the cutting fluid. It was found that the developed cutting fluid could decrease both the machining force and tool wear and get good surface quality owing to its good lubricating ability for titanium alloys.

The last decade has seen a significant growth in the market for alloys used for implants, especially for those intended for orthopedic implants. Research into biodegradable magnesium-based alloys has made great strides in this period, so huge progress has been made in their use in the medical industry. The important factors that led to the intensification of research in this regard, were social but also economic, wanting to improve the quality of life, by reducing the use of conventionally permanent metallic implants (stainless steel, cobalt-based alloys, and titanium alloys) which involve the second implant removal surgery and other undesirable effects (stress shielding and metal ion releases), with a negative impact on the emotional and physical condition of patients, and by significantly reducing the costs for both the patient and the health system in the field of orthopedics. This paper refers to the impact and importance of biodegradable Mg alloys, reviewing the beginning of their development, the significant characteristics that make them so desirable for such applications (orthopedic implants) but also the characteristics that must be modulated (corrosion rate and mechanical properties) to arrive at the ideal product for the targeted application. It highlights, in detail, the mechanism and aspects related to the corrosion behaviour of Mg alloys, electrochemical characterization techniques / methods, as well as strategies to improve the corrosion behaviour and mechanical properties of these types of biodegradable alloys. The means of optimization, the category and the effect of the alloying elements, the design criteria, the requirements that the implants of biodegradable alloys Mg-based must meet and the aspects related to their efficiency are also presented. Finally, the potential applications in the specialized clinics, as well as the final products currently used and made by important prestigious companies in the world are approached.

The machining of nickel and titanium-based superalloy components is very expensive and involves unusually high lead times compared with other engineering metals such as steels and aluminum. This has led to the development of most suitable additive manufacturing (AM) processes to fabricate these difficult-to-machine metals into near-net shape parts, thereby reducing the lead time and material waste, and significantly increasing productivity. Nonetheless, finish machining is still required on the AMed metal components to meet the dimensional and surface requirements of the application. Several research studies have investigated the machinability of AMed nickel and titanium alloy workpieces and have compared the results with the machining responses of wrought counterparts, which is detailed in this review. The categorization of the literature is based on the machining operations including turning, milling, drilling, and non-conventional machining, and the observations are discussed in accordance with various input parameters such as workpiece characteristics (hardness, microstructures) and anisotropy in mechanical properties due to build orientations during the AM process. Moreover, the influence of these parameters on cutting forces and temperatures, chip formation, and tool wear is analyzed and reported. From this review, it is found that the machinability of AMed nickel and titanium workpieces is quite different to the machining responses of their wrought counterparts. Further thorough experimentation is required to develop optimized machining parameters for AMed metal parts, while an exploration of different cutting tool geometries, coolant, and lubrication strategies for enhanced tool performance for machining AMed workpieces is essential. Finally, this study reviews the state of contemporary research, and offers suggestions for future research.

Satellite propellant tanks are mostly built from titanium alloys using expensive forgings, which have a long lead time and require significant amounts of machining. The propellant tank components are then welded using fusion-based welding techniques like electron beam or tungsten inert gas welding, that can cause loss of joint strength due to imperfections produced during solidification. To reduce the manufacturing time and associated costs, an alternative method of tank manufacturing has been developed. This study describes the application of a casting technique to manufacture tank end domes and the cylindrical sections using titanium alloy Ti-6Al-4V. The domes and cylindrical parts are machined to the required geometry and welded together using Friction Stir Welding. The microstructure and mechanical performance of the tank parts was evaluated and compared to that of a conventionally manufactured tank. Although there was a slight degradation in weld elongation, the fracture toughness and the stress corrosion cracking properties were quite similar before and after welding. The fabrication of propellant tank components using the casting technique has offered typically five times lower cost and two-third reduction in lead time when compared to the forging and forming process route.

In sugar industry, the sugar processing done in different sections, but to increase total crushing per day (TCD) capacity, the milling section takes a vital role in the sugar industry. The sugar industry aims to extract the maximum amount of juice from sugarcane. In the milling section, the processed sugarcane is fed in between the three-roller shaft from the different arrangements, there are different loads applied on each part roller shafts. When load between all rollers varies then there is a chance of bending it is analyzed to check the roller shaft condition. The modeling is done on roller shaft with the help of CATIA V5. After modeling, we analyze the condition of the rollers, when different stress or forces are applied to different sections of the roller shaft it analyzed with the help of Finite element method using ANSYS WORKBENCH software. We were selecting titanium alloy materials for the roller shaft to analyze the variation in results. When comparing the calculated and software-based results using Maximum Shear stress and Total deformation for top, feed, and discharge rollers said the roller shafts are safe to use in the sugar industry and titanium alloy is the best material for these roller shafts.

This study investigated the effect of microstructural decomposition on the mechanical properties of additively manufactured Ti-6Al-4V by directed energy deposition. The formation of α’ martensite and α massive phase (αm) was observed in the deposited layers. The α’ and αm in the lastly deposited layer appeared as a needle-shaped and a sub-lamellar structure, respectively. However, the morphology of α’ and αm was decomposed in the lower layers due to the intrinsic heat treatment. Moreover, The heat conduction rate calculation showed that the lower powder feed rate generates more heat conduction. Therefore, the microstructure was further decomposed for the specimen with a lower powder feed rate. These phenomena consequently affected the mechanical properties and fracture behavior of the Ti-6Al-4V alloy.

This paper addresses the use of alloying additions to titanium alloys for additive manufacturing (AM) with the specific objective of producing equiaxed microstructures. The additions are among those that increase freezing ranges such that significant solutal undercooling results when combined with the rapid cooling rates associated with AM, and so be effective in inducing a columnar-to-equiaxed transition (CET). Firstly, computational thermodynamics has been used to provide a simple graphical means of predicting these additions; this method has been used to explore additions of Ni and Fe to the alloy Ti–6Al–4V (Ti64). Secondly, an experimental means of determining the minimum concentration of these alloying elements required to effect the CET has been developed involving gradient builds. Thirdly, it has been found that additions of Fe to Ti64 cause the alloy to change from an α/β Ti alloy to being a metastable β-Ti alloy, whereas additions of Ni do not produce the same result. This change in type of Ti alloy results in a marked difference in the development of microstructures of these compositionally modified alloys using heat treatments. Finally, hardness measurements have been used to provide a preliminary assessment of the mechanical response of these modified alloys.

Orthopaedic metallic implant design is expected to meet two critical challenges—biocompatibility and mechanical strength. According to a survey conducted in 2017, the global market of implants will grow by ~46% by 2025. Researchers have been trying to alleviate the problems of these implants, namely, biocompatibility, microbial invasion, bio-inertness, corrosion, and wear. Surface modification techniques that operate at low temperature and diffusion-based processes are preferred to circumvent the problems. These methods include thermochemical (carburizing, nitriding, etc.), electrochemical processes (electrochemical deposition, chrome plating, etc.), and ion implantation. This review presents the significance of these methods while meeting various challenges, such as wear, biocompatibility, and corrosion. The implants reviewed are stainless steel, Co-Cr alloys, titanium alloys, and magnesium alloys. Finally, the friction-stir process, another low-temperature process, has been reviewed for Mg and its alloys.

The composition of polishing slurry plays an important role in the material removal rate (MRR) and surface roughness of titanium alloy. In this study, chemical mechanical polishing (CMP) was used to polish TA31 titanium alloy, the MRR and surface roughness of the titanium alloy were used as evaluation indicators, and the abrasive concentration (A), H2O2 concentration (B), and pH (C) were used as the influencing factors to carry out the orthogonal experiment of titanium alloy free abrasive polishing. In this study, the composition of the polishing slurry was optimized, and the oxidation–reduction potential (ORP) of different polishing slurries was detected. Furthermore, the mechanism of the influence of the composition of different polishing slurries and ORP on the removal of polishing materials was discussed. The results of the study show that the best polishing rate is 43.991 nm/min, and the best surface roughness is 0.045 μm. The order of significant factors affecting the removal rate of titanium alloy is A (abrasive concentration) > B (H2O2 concentration) > C (pH), and the order of significant factors affecting the surface roughness of titanium alloy is C (pH) > A (abrasive concentration) > B (H2O2 concentration). The optimal slurry composition for material removal rate is abrasive concentration of 3%, H2O2 concentration of 5% and pH = 3, and the optimal slurry composition for surface roughness is abrasive concentration of 3%, H2O2 concentration of 5% and pH = 12. The research can lay an experimental foundation for further study on the mechanism of CMP of TA31 titanium alloy.

Titanium (Ti)-based alloys wield unique combination of mechanical, chemical, and high temperature properties, which place them at the forefront of engineering applications ranging from biomedical t...

This paper presents the research results of the hydrogen distribution in welded joints made by electron beam welding of titanium alloys VT20 and VT23. The distribution of hydrogen in the cross-sect...

Wire and arc additive manufacturing (WAAM) is considered to be an economic and efficient technology that is suitable to produce large-scale metallic components. In the past few decades, it has been widely investigated in different fields such as aerospace, automotive, and marine industries. Due to its relatively high deposition rate, low machinery cost, high material efficiency, and shortened lead time compared to other powder-based additive manufacturing (AM) techniques, WAAM has been significantly noticed and adopted by both academic researchers and industrial engineers. Titanium alloys as valuable metallic materials have been increasingly applied in aeronautics and astronautics fields owing to their excellent comprehensive properties. However, there are many challenges to fabricate large-scale titanium components with traditional manufacturing methods, particularly in consideration of complex component geometries and high Buy-To-Fly (BTF) ratio. Therefore, due to the advantages of relatively low manufacturing cost, good quality, and high efficiency, WAAM is becoming popular to fabricate near-net-shape and large-scale titanium alloy in recent years. This paper provides an overview of the 3D metallic printing of titanium alloy by employing WAAM as the deposition method. At first, the review introduces titanium alloys and WAAM technique, followed by WAAM systems which are used to manufacture titanium, and post-treatment which aims to optimize microstructure, improve mechanical properties, and eliminate residual stress of the WAAM deposited titanium components. Afterward, the economic applicability of applying WAAM on titanium alloys is also discussed. In the end, applications in various fields of WAAM titanium components are displayed.

Machinability of Grade 5 titanium alloy, despite its extensive usage in fields of aerospace and biomedical applications, is extremely challenging as a result of various features like its poor therm...

Titanium alloys have excellent specific strength, outstanding corrosion resistance, and good biocompatibility, which are widely used in mechanical and medical fields such as compressor disc, blade, stator, and hip and knee joint. Titanium alloy workpieces must be machined to obtain specific shapes. However, the machining marks inevitably exist on the titanium alloy surface, which have a poor effect on the performance of workpieces. Therefore, polishing is scheduled at the subsequent process to remove the machining marks. Because titanium alloys are typically difficult-to-polish materials, the polishing surface quality and efficiency require to be improved further. To have an in-depth and comprehensive understanding of the polishing technology of titanium alloys, this paper reviews systematically the material’s polishing mechanisms and processes. To date, various fundamental mechanisms, including mechanics, heat, optic, electricity, magnetism, ultrasound, and chemistry, are employed to polish titanium alloy surface. On this basis, four types of polishing techniques were developed (i.e., mechanical polishing, high-energy beam polishing, chemical polishing, and compound polishing) to improve the high surface integrity of titanium alloys. Furthermore, the advantages and disadvantages of each polishing technique are discussed in detail from the views of model, optimization, equipment, efficiency, surface quality, and cost. Finally, this paper proposes the future development directions of the polishing techniques of titanium alloys.

A novel low temperature and green salt bath nitriding of TC4 titanium alloy was developed by adding a certain amount of K2SO4 in the KNO3 and NaNO3 salt bath. The results show that compared with as...

Titanium alloys with light weight and high strength at 300–400 °C have been widely used in aerospace industry. Vacuum brazing technique with the advantage of low stress and high efficiency for Ti-based alloy has been developed for manufacturing the components in complicated structure such as heat exchanger. The newly designed filler material as Ti-12.5Zr-13.7Cu-11.6Ni-2.2Ag wt% was used for brazing the dissimilar joint of CP-Ti (as TA2) and Ti6Al4V. A sound joint with strength as 469 MPa and impact toughness as 4.5 ~ 5.0 J/cm2 were achieved by brazing process as 875 °C/10 min. A few amounts of intermetallics as TiNi3 and Ti2Cu phases with the fraction as 7.82 vol.% and 0.0126 vol.%, respectively, was examined in the joint, which were thought to balance the strength and the ductility of it. The fine distributed phase of TiNi3 with soft orientation as {0001}[11–20] was benefit for the ductility of the TA2-Ti6Al4V joints.

Silicon (Si), which exists in the form of solid solution and silicide, is an important component in high temperature titanium (Ti) alloys. The content of Si is often limited to less than 0.5wt.%, but powder metallurgy shows the potential for the preparation of titanium alloys with high Si content and high temperature. The addition of Si is beneficial to the improvement of strength, creep resistance and oxidation resistance of high temperature titanium alloy, but it will reduce the plasticity, especially the plasticity at room temperature. In this review, with particular stress on the influence of heat treatment and hot working process on the precipitation behavior of silicide, as well as on the effect of Si on the properties and strengthening mechanism of high temperature titanium alloys. The development direction of high temperature titanium alloy containing Si is to increase the content of Si and to control the precipitation behavior of silicide through reasonable process.

Ti-15-3 titanium alloy has been widely used as a connecting material for aerospace structural parts. However, the non-uniform pitting caused by salt spray corrosion and the limitations of the conventional electrochemical techniques in predicting localized corrosion seriously prevent the practical application of Ti-15-3 alloy. Herein, the electrochemical noise based on discrete wavelet transform and Hilbert-Huang transform is employed for studying pitting corrosion of both the untreated and polished Ti-15-3 alloy under different neutral salt spray time. Combining with the further analysis of the electrochemical impedance spectroscopy, a complementary evaluation is used to analyze the effect of surface roughness on pitting corrosion behaviors of Ti-15-3 alloy systematically. It is found that pitting forms of both surface roughness electrodes exposed to different salt spray time are successfully distinguished, and the polished Ti-15-3 alloy shows better corrosion resistance. Microstructural characterization confirms the inferences from electrochemical noise analyses, the results indicate that the smooth surface of the polished Ti-15-3 alloy is less vulnerable to the coexistence of metastable pitting and the growth of stable pitting, and effectively improves the resistance to pitting corrosion of Ti-15-3 alloy. Furthermore, a possible mechanism for the triggering of pitting corrosion of Ti-15-3 alloy with different roughness in salt spray environment is proposed. This work will provide significant insights for rational design of Ti-15-3 alloy used in the tropical ocean facilities to avoid the attack of pitting corrosion.

—The influence of the parameters of dc reaction magnetron sputtering of two monoelement targets (Ti, Pb) onto substrates made of a VT6 titanium alloy and 12Kh18N10T steel on the microhardness, the phase composition, and the texture of the sputtered composite coatings is studied. The coatings consist only of Pb and PbO at a lead cathode current of 0.2 A and also include TiN at a current of 0.1 A. The coatings on the VT6 alloy have a higher microhardness as compared to the coatings on 12Kh18N10T steel, which is due to the nitriding-assisted hardening of titanium substrate. The following correlation of the texture with the microhardness is found: the (111) pole density increases threefold and the microhardness of coatings decreases sharply when the ratio of the argon and nitrogen flow rates increases from 2.08 to 4.3.

The paper investigates a roughness of titanium α, α+β and β alloys, obtained by wire electrical discharge machining (EDM) with a brass electrode-tool in distilled water. The purpose of the article is to establish the relationship between the electrical parameters of wire EDM with the surface roughness α, α+β and β of titanium alloys, in particular with the group of parameters Rk. It was established by the method of contact profilometry that the phase composition of titanium alloys significantly affects the height parameters of the roughness of the treated surfaces. It was shown experimentally that the phase composition has a significant effect on the roughness parameters of the Rk group obtained in the process of EDM

When grinding titanium alloys with a silicon carbide wheel, the coolant provides cut-free grinding, a decrease in the performance of the grinding process. The coolant has a significant effect on the ratio of the same components of the cutting force on the counter and passing passes of the table when grinding steels with a corundum wheel and titanium alloys with a silicon carbide wheel.

Ti6A14V is a well-known ‘Difficult to Cut’ material in the aerospace industry. Ti6Al4V shows strain hardening, poor thermal conductivity and chemical reactivity at elevated temperatures, which impl...