TC4 Titanium Alloy Research Articles

Experimental study on the influence of welding structure details of TC4 titanium alloy under thermo-vibration coupling environment on vibration fatigue life

The widespread application of titanium alloy materials in aerospace structural design makes them susceptible to thermo-vibration coupling fatigue failure in harsh vibration and thermal environments. Vibration fatigue issues significantly affect the safety and operational reliability of aircraft. In order to obtain optimal design details for titanium alloy welding structures under thermo-vibration coupling conditions, experimental specimens with different structural details of TC4 titanium alloy welding structures were designed to simulate actual structural designs. The structural details included skin with U-shaped supports at different angles, skin with L-shaped supports, and skin with T-shaped supports. A thermo-vibration coupling vibration fatigue test system was established, and vibration fatigue tests were conducted at a temperature of 150°C. All structural fatigue crack failures occurred at the welds. The experimental results were statistically analysed, and using the Chauvinet criterion, abnormal data points were removed. The influence of structural details on vibration fatigue life was determined through F-tests. It was found that for the skin with a U-shaped support structure, a support angle of 90° resulted in a longer vibration fatigue life. When comparing skin with T-shaped support and skin with L-shaped support structures, the T-shaped support structure exhibited a longer vibration fatigue life. Among the three structural types, the skin with a T-shaped support structure has the longest vibration fatigue life. These experimental conclusions serve as important references for the design of thin-walled structures in aircraft structural design.

Effect of laser power on microstructure and properties of laser cladding AlCoCrNiSiTi0.5 high-entropy alloy coatings

Abstract Using varying laser powers, an AlCoCrNiSiTi0.5 high-entropy alloy (HEA) coating was applied to the surface of TC4 titanium alloy. The microstructure and phase composition of the coating were examined using several analytical techniques, including energy spectrometer (EDS), scanning electron microscopy (SEM), and X-ray diffraction (XRD), etc., and Vickers hardness tester was used to test the coating’s microhardness at various laser powers. Studies indicate that the coating is mostly made up of the following phases: BCC, FCC, α-Ti, β-Ti, (Si, Al)2Cr, (Ni, Co)Ti2; The coating’s mean hardness under different powers (1400 W, 1600 W, 1800 W) is 1047.87 HV, 1012.68 HV, and 846.72 HV, which is about 2∼3 times of the matrix hardness (347.27 HV). Powder overburning will occur at laser energies greater than 1800 W. The elements evaporate, thereby reducing the microhardness of the coating. The hardness of TC4 titanium alloy can be greatly increased by applying an AlCoCrNiSiTi0.5 HEA coating.

Study on the wear resistance of micro-arc-oxidised ceramic films on the surface of TC4 titanium alloy oil well tubing in the Ordos Basin

The use of titanium alloy oil well pipes in conventional and unconventional oil and gas explorations, developments and drillings in gas fields in the Ordos Basin is increasing. However, ensuring the safety of titanium alloy tubing is challenging because of the poor friction and wear resistance of these alloys. Herein, we strengthened the surface of a TC4 alloy oil well pipe through micro-arc oxidation to prepare oxidised ceramic films (MAO-TC4). Further, we investigated their friction and wear behaviours under different normal loads to analyse related mechanisms and improve the safety of titanium alloy oil well pipes. The results reveal a positive correlation between the coefficient of friction and wear volume under the normal load. In addition, the wear characteristics of MAO-TC4 are superior to those of the TC4 alloy in all contact forms. When paired with TC4 alloy balls, the adhesive wear and abrasive wear are dominant wear mechanisms. Meanwhile, when paired with Si3N4 ceramic balls, the wear mechanism is abrasive wear at the contact edge and slight oxidative and fatigue wear at the contact centre. Moreover, the MAO-TC4 alloy can effectively reduce oxidative wear. The cutting-to-plasticity ratio ( fcp) of MAO-TC4 is 0.8, and we weakened the micro-cutting mechanism to prevent material loss compared with TC4, which has an fcp of 0.95. In conclusion, MAO-TC4 can resist frictional wear at the alloy end face of titanium alloy oil well pipes. In addition, this study provides design concepts for improving the performance of the end face in the oil and chemical design for titanium alloys.

Numerical simulation of electron beam welding and local heat treatment of TC4 titanium alloy sheet

Numerical simulation of electron beam welding and local heat treatment of TC4 titanium alloy sheet

Effect of binder phases on the microstructure and sliding wear properties of HVOF-sprayed WC-based coatings

This study aimed to evaluate the microstructure and wear properties of WC-10Co-4Cr, WC-12Co, and WC-17Co coatings on TC4 titanium alloy. The coatings were deposited using high velocity oxygen-fuel (HVOF) technique. To analyze the influence of binder phases, the coatings were thoroughly examined using scanning electron microscopy, X-ray diffractometer, microhardness tester, and friction and wear tester. The analysis of the results reveals that the primary phases in all three coatings consist mainly of WC, with smaller quantities of W2C and amorphous phases present. The WC-10Co-4Cr powder demonstrates a relatively even particle size distribution, high degree of sphericity, and rough porous surface, allowing for efficient heat absorption and uniform heat distribution, resulting in a dense coating. Notably, the WC-10Co-4Cr coating exhibits significantly smaller tungsten carbide grain size compared to the other coatings. Moreover, the microhardness of the WC-10Co-4Cr coating, measured at 1377.8 HV0.05, is significantly higher than that of the WC-12Co and WC-17Co coatings, which measured at 1258.8 HV0.05 and 1182.4 HV0.05, respectively. Additionally, the WC-10Co-4Cr coating demonstrates low friction coefficient and wear volume, indicating excellent wear resistance. Subsequently, a comprehensive analysis was conducted to determine the reasons for the relative enhancement in binder performance.

Study on the structure, growth pattern and corrosion behavior of CoCrFeNiAl high entropy alloy coatings - base on hollow cathode effect

The surface of TC18 titanium alloy was coated with a CoCrFeNiAl HEA coating using double-glow plasma surface metallurgy. The structure, phase, and growth mode of the coating were investigated, along with its electrochemical corrosion behavior. The prepared HEA coating, under the influence of the hollow cathode effect and non-equilibrium diffusion, exhibits a composite structure consisting of a deposited layer and an interdiffused layer. It demonstrates robust metallurgical bonding with the substrate, and it exhibits a hardness of 12.66 GPa and an elastic modulus of 158.52 GPa, along with exceptional hardness and high elastic modulus. The primary phase of the coating consists of an FCC solid solution, with a minor presence of Ni3Al and Al8Cr5 phases. TEM results demonstrate that hollow cathode enhanced sputtering effectively refines the grain structure on the substrate surface. The high entropy alloy coating, characterized by a significant abundance of nanocrystalline and amorphous structures, is obtained under the bombardment of high-energy particles. Gradually increasing from the interface to the deposited layer, there is an augmentation in the content of nanocrystals. The transition from the substrate to the sedimentary layer comprises three distinct regions: a surface fine crystal region, a nanocrystalline structure region, and a nanocrystalline and amorphous precipitated phase-rich region. In 3.5 wt% NaCl solution, the electrochemical corrosion rate of the coating is 1.36 × 10−1 μm·year−1, which is about ten times lower than that of the substrate. Moreover, pre-soaking forms a stable oxide film on the coating's surface, effectively preventing corrosion and demonstrating its remarkable corrosion resistance.

Tailoring microstructure and mechanical anisotropy of laser-MIG hybrid additive manufacturing TC11 titanium alloy through solution aging treatment

Tailoring microstructure and mechanical anisotropy of laser-MIG hybrid additive manufacturing TC11 titanium alloy through solution aging treatment

Ultrasonic rolling strengthening of TC11 titanium alloy surface: Corrosion and wear properties under extreme conditions

The surface of TC11 titanium alloy was polished and strengthened using ultrasonic rolling process (USRP) technology. The effects of USRP on the surface quality, friction and wear properties, corrosion resistance, and wear mechanisms of TC11 titanium alloy at room temperature, low temperature (−60 °C), high temperature (400 °C), and in corrosive environments were investigated by using optical microscope, microhardness tester, electrochemical workstation, multifunctional friction and wear tester, SEM, EDS, XRD, and XPS. The results indicate that USRP can effectively refine the surface grains of titanium alloy, reducing its surface roughness parameter by 80.4 % and increasing surface hardness and residual compressive stress by 21.7 % and 97.1 %, respectively. USRP is advantageous for producing a layer of TiO2 on the surface of titanium alloys, effectively enhancing the corrosion resistance of titanium alloy surfaces. USRP technology can improve the stability of surface hardness values of titanium alloys in harsh environments. The results of dry friction and wear tests using GCr15 steel balls as the counter material show that the USRP technology can effectively reduce the friction coefficient and wear loss at room, high and low temperatures. The results of corrosion and wear tests using Si3N4 as the counter material indicate that the USRP technology can effectively reduce the friction coefficient and wear volume in seawater corrosion environments. The USRP technology is most effective in reducing the high-temperature friction coefficient of titanium alloys and improving their wear resistance in low-temperature and corrosive environments. The primary wear form of TC11 titanium alloy after USRP has shifted from adhesive wear to abrasive wear.

Effect of AC/DC mixed current waveform on surface oxidation, microstructure and mechanical properties of TIG welded TC4 titanium alloy

Coarse β-grains and severe surface oxidation are major factors plaguing the comprehensive properties of tungsten inert gas (TIG) welded joints of titanium alloy. To improve the performance of welded joints, a novel current waveform, alternating current/direct current (AC/DC) mixed current waveform which was named Mix-TIG was proposed. In Mix-TIG, the oxide film on the weld surface is broken up by the cathodic crushing effect. Cyclic variations of the current waveform produce stronger arc stirring and more intense oscillations in the molten pool which results in grain refinement. In addition, the lower temperature gradient in the melt pool due to the smaller heat input in Mix-TIG also contributes to grain refinement. The elongation and microhardness of the Mix-TIG were increased.

Design and surface analysis in large-amplitude longitudinal ultrasonic vibration-assisted milling of TC4 titanium alloy under dry conditions

Design and surface analysis in large-amplitude longitudinal ultrasonic vibration-assisted milling of TC4 titanium alloy under dry conditions

Fatigue cracking behavior and life assessment of TC11 titanium alloy in very high cycle regime at two working temperatures

Axial loading fatigue tests were conducted with two stress ratios to investigate fracture surface behavior and associated failure analysis governing crack nucleation of TC11 titanium alloy at two working temperatures, spanning high-cycle and very high-cycle fatigue regimes. Furthermore, scanning electron microscopy, optical microscopy, and electron-backscattered diffraction techniques were employed to analyze the cracking mechanism. The interior failure is attributed to the cleavage of the large equiaxed αp-grains and facet-facet cluster area-fisheye formation. Moreover, the crack growth threshold values and the transition sizes from small to long cracks decrease with temperature rise. In addition, small cracks follow the path that requires minimum energy for propagation as per the microstructural orientation and are governed by maximum shear stress, resulting in the formation of crystallographic facets. Based on the analysis above, the interior fracture mechanism was summarized as related to the microstructure characteristics. Considering the fatigue cracking behavior and microstructural features, a model for predicting crack nucleation life is developed, exhibiting a better consistency between predicted and experimental fatigue lives.

Variable cycle fretting conditions meditated wear behavior and mechanism in a self-lubricating composite coating on TC21 titanium alloy substrate

To simulate the variational working conditions of the titanium fastener in the aero-engine, variable cycle fretting wear tests were carried out for normal loading (80/40 N), frequency (100/30 Hz), displacement amplitude (80/40 µm) and operating temperature (500/350 °C) in a self-lubricating composite coating on TC21 titanium alloy substrate, and the fretting wear behavior and wear mechanism were thoroughly investigated. The results shows that the coefficient of friction (COF) and the wear volume present a significant difference under variable cycle fretting conditions. The specimen exhibits a relatively stable COF under variable operating temperature. Whereas for the specimen under variable displacement amplitude presents a lowest wear volume. The adhesive wear is mainly found in the specimens under variable normal loading and frequency. Whereas for the specimens under variable displacement amplitude and operating temperature, abrasive wear and oxidation wear is mainly dominated, respectively. The dissipated energy calculation results demonstrate that the variable displacement amplitude and operating temperature have greater impact on the fretting wear behavior. The microstructure analysis in the cross-section of specimens reveals that the sub-surface is composed of amorphous-nano crystalline layer, plastic deformation layer and the origin coating. Additionally, the wear mechanism of the specimens under variable fretting conditions were deeply revealed. This work can provide essential information on fretting behavior and mechanism under the variational working conditions.

Dynamic response of TB9/TC4 titanium laminated composite with strong bonding interface

Taking advantage of high strength of a titanium alloy and high ductility of the other one is performed to manufacture titanium laminated composite that is promisingly applied in high strain rate environments, but the challenge of fabricating high bonding interface of the two titanium alloys still needs to be overcome. In this work, the TB9/TC4 titanium laminated composite was successfully prepared by hot rolling. A strong bonding interface was constructed between the layers of TB9 and TC4 titanium alloys, achieving a high shear strength of up to 770 MPa. The dynamic compression of the TB9/TC4 titanium laminated composite under Split Hopkinson Pressure Bar (SHPB) showed that the stress-strain curve of the composite presented a unique dual-peak feature, indicative of an excellent strain hardening capability. The TB9/TC4 interface, characterized by coherent and low interface formation energy, facilitated deformation accommodation between TC4 and TB9 layers. Concurrently, the TB9/TC4 interface hindered the ASBs and triggered dislocation strengthening due to stress concentration, leading to high dynamic strength of the laminated composite.

Transfer learning-based quality monitoring of laser powder bed fusion across materials

Laser powder bed fusion (LPBF) is a promising additive manufacturing (AM) technique that has gained rapid growth. Despite the unique advantages such as producing complex-shaped metal parts, LPBF has been still slowed by the poor process repeatability and part consistency. In-situ monitoring methods combining sensing sensors and machine leaning (ML) tools have attracted much attention for defect detection and quality identification. However, the current ML algorithms usually rely on the availability of massive labeled datasets, and the trained model for monitoring a certain powder material cannot be directly applied to monitoring another material with different properties. Moreover, for a new material, it is time-consuming and expensive to collect the sufficient labeled data for building the quality monitoring model from scratch. To this end, motivated by transfer learning (TL), we propose a TL-based quality monitoring approach across two different materials in the LPBF process. Three different sensing datasets of layer-wise images of the solidified layer, photodiode signals, and acoustic emission signals are separately transferred from the 316L stainless steel to the TC4 titanium alloy. A convolutional neural network (CNN)-based quality monitoring model is first built by the sufficient source datasets from 316L stainless steel material. Then, the pre-trained CNN model is fine-tuned with a small amount of the target datasets for quality monitoring on TC4 titanium alloy material. Experimental results demonstrate the effectiveness of the proposed method for quality monitoring from one material to another with limited target datasets, with a classification accuracy above 92 % just with 5 % of target datasets on all three transferred datasets.

Effect of copper addition on passivation film of TC18 titanium alloy

TC18 and TC18–0.5Cu alloys were prepared by vacuum arc furnace melting. The properties of its passivation film in 5 % NaCl solution were investigated using constant potential polarization, electrochemical impedance spectroscopy, Mott-Schottky and XPS analysis. The corrosion resistance of TC18 passivation films was found to be superior to that of TC18–0.5Cu alloy. The passivation films formed on both alloys displayed n-type semiconductor behavior. In the TC18–0.5Cu alloy, the presence of copper as a form of copper interstitial segregation Cuix+ was observed, which was subsequently replaced by low-mobility titanium ionic vacancies in the form of a cationic sublattice CuTix′, as a small defect.

The microstructures and mechanical properties of the TC4 titanium alloy fabricated by laser composite manufacturing technology

The effective combination of traditional forging and laser three-dimensional forming technology can play a crucial role in the preparation of large metal part with fine structures, thereby accelerating the manufacturing cycle of parts and reducing costs. This study used laser composite manufacturing technology to perform complete annealing heat treatment on TC4 titanium alloy structural part produced from traditional forgings. The analysis of microscopic structure, chemical composition, and mechanical properties has verified that the overall mechanical properties consistency of the composite manufacturing part has been effectively improved. The results indicate that laser composite manufacturing part have good metallurgical bonding, and there is no component segregation phenomenon in the composite manufacturing area. After complete annealing, the α lath in the composite manufacturing part is coarsened, the strength of the laser forming area is reduced, and the consistency of mechanical properties of the forging area and the laser forming area is enhanced. The consistency of strength of the two areas is increased from 78% before heat treatment to 84%.

Effect of three-stage heat treatment on mechanical properties and micro-deformation mechanism of TC4 titanium alloy welded joint

The influence of three-stage heat treatment on the microstructure and mechanical properties of pulsed laser-arc hybrid welded TC4 titanium alloy joints was studied by experiments and molecular dynamics calculations. The results showed that after the three-stage heat treatment, a large number of fine and diffusely distributed secondary α phases were found in the welded joint, which increased the content of the phase boundary. The TEM characterization and calculation results show that the phase boundary had a strong hindering effect on the dislocation slip. As a result, under three-stage heat treatment conditions, the hardness of the welded joint was increased by 50%, and the yield strength and tensile strength of the welded joints were increased by 24.3% and 13.9%, respectively. The impact toughness of the base metal significantly improved after heat treatment, which was 31.6% higher than that before heat treatment due to the increase in the equiaxed α phase from the weld metal to the base metal. A large number of stacking faults were generated during the tensile deformation of the welded joint before heat treatment due to the low stacking fault energy of the α phase, which could effectively release the stress and hinder the dislocation slip. After heat treatment, the stacking fault of the welded joint decreased owing to the obvious increase in stacking fault energy. The micro-cracks propagated rapidly along the lamellar α phase to fracture. Therefore, the plasticity of the welded joint decreased, although the strength was improved after heat treatment.

Investigation of hot deformation behavior and microstructure evolution of TC18 alloy and establishment of constitutive equation under friction-temperature correction

The effects of deformation temperature and strain rate on the microstructure evolution of TC18 alloy are studied by hot compression experiment and EBSD test, based on the double correction of friction and temperature rise in hot compression, a more accurate constitutive equation and thermal processing diagram are established. Recrystallization grain is the main microstructure of TC18 alloy during deformation from 810 °C to 930 °C. Higher deformation temperature and lower strain rate are beneficial to the occurrence of dynamic recrystallization and grain size growth. The strain rate has no significant effect on volume fraction of large and small angle boundary. After double correction of temperature rise and friction, it is found the activation energy of TC18 titanium alloy in β region and α/β region are 485.895 kJ/mol and 355.337 kJ/mol, respectively. The ideal hot working conditions of TC18 titanium alloy are 812 °C ∼ 840 °C, 0.01 s−1 ∼ 0.018 s−1 and 878 °C ∼ 915 °C, 0.178 s−1 ∼ 1.0 s−1, respectively. The unevenness of microstructure, the large size difference among grains and the large orientation difference among grains lead to the instability of hot working process. The conclusions of this paper can provide more accurate guidance for the determination of hot working parameters and the prediction of microstructure evolution during hot working of TC18 alloy.

Dynamic response and roughness control of surface materials on TC4 titanium alloy subjected to laser shock wave planishing

Abstract In this study, ABAQUS was used to predict the dynamic response of surface materials on TC4 titanium alloy during laser shock wave planishing (LSWP). The experiments were conducted to evaluate the simulations. The results indicate that during the initial stage of LSWP, the contact status between the contact foil and the micro-protrusion changes from the one-dimensional stress state to the one-dimensional strain state. This causes the high-amplitude tensile residual stress to converge at the center of the flattened micro-protrusion surface. When treating specimens with high surface roughness, the application of a thin contact foil can significantly lower the height of micro-protrusions and lift the bottom of micro-depressions. This improves the plastic flow of micro-protrusions and prevents the convergence of tensile residual stress. Using a thick contact foil can help extend the pressure pulse duration and prevent the overall surface profile subsidence when treating specimens with lower surface roughness. The outcomes of the experiment and the simulation agree rather well. Additionally, a thick contact foil can reduce the build-up of tensile residual stress by reducing the contact pressure.

Construction of a Predictive Model for Dynamic and Static Recrystallization Kinetics of Cast TC21 Titanium Alloy

In this study, hot compression experiments were conducted on cast TC21 titanium alloy using a Gleeble-1500D thermal simulation compression tester, and the hot-compressed specimens were heat-treated. The data obtained after analyzing the thermal compression of cast TC21 titanium alloy were analyzed to construct a thermal machining diagram with a strain of 0.8 and to optimize the machining window. This study investigated the microstructure of the alloy after hot pressing experiments and heat treatment, applying the study of the microstructure evolution law of cast TC21 titanium alloy. The analysis of the tissue evolution law established the dynamic and static recrystallization volume fraction as a function of heat deformation parameters. The results show that the optimal processing window for cast TC21 titanium alloy is a deformation temperature in the range of 1373 K–1423 K and a strain rate of 0.1 s−1. The increase in deformation volume and deformation temperature both favor recrystallization and make the recrystallization volume fraction increase, but the increase in strain rate will inhibit the increase in the recrystallization degree to some extent. The dynamic and static recrystallization equations for the cast TC21 titanium alloy at different temperatures were constructed. The experimental measurements of recrystallization volume fraction are in good agreement with the predicted values.