Titanium Aluminum Alloy Research Articles

A Study on the Fatigue Life of the Laser Additive Manufactured Metallic Material

As more and more structural parts of military aircraft are formed with additive manufacturing (AM) technology, it was very urgent to study fatigue characteristics of additive manufacturing materials and structures. In order to study the fatigue life characteristics of aluminum alloy and titanium alloy manufactured by selective laser melting (SLM), a series of specimens with various structural details were designed and tested under constant amplitude and random spectrum. The basic reliability life of each test results was statistically analyzed and the reliability safety life curve was obtained. Fractography analysis showed that there were more defects and mixed failure characteristics in aluminum alloy specimens, while the fatigue-scatter of titanium alloy counterpart was larger than that of forgings.

Diamondlike Carbon Surface Treatment Improves the Fatigue Resistance of Ultrasonic Tips

IntroductionThe aim of this study was to compare E1-Irrisonic (Helse Ultrasonics, Ocoee, FL) and Irri Black (Helse Ultrasonics), a novel ultrasonic tip with diamondlike carbon treatment, regarding their design, metallurgy, microhardness, bending resistance, and time to fracture under the oscillatory fatigue test. MethodsA total of 17 E1-Irrisonic and 17 Irri Black new ultrasonic tips were selected. The tip geometry and surface finishing were assessed using scanning electron microscopy. The elemental composition was defined by energy-dispersive X-ray spectroscopy. Hardness Knoop was calculated using a microhardness tester. The maximum load required to displace the instrument in 45° was recorded in gram/force, oscillatory fatigue was measured in seconds at the moment of instrument fracture, and the size of the separate fragments was determined in millimeters. The Student t test was used for statistical comparison (α = 5%). ResultsScanning electron microscopic analyses revealed that E1-Irrisonic had a flat end tip, whereas a noncutting rounded tip was observed in Irri Black. The surface of E1-Irrisonic was smoother than Irri Black, which was irregular. Energy-dispersive X-ray spectroscopic analyses showed that the elemental compositions of the E1-Irrisonic and Irri Black tips were consistent with stainless steel and titanium-aluminum alloys, respectively. Irri Black showed significantly higher bending load resistance, time to fracture under oscillatory motion, and hardness Knoop than the E1-Irrisonic tip (P < .05), whereas the length of fragments was similar (P > .05). ConclusionDiamondlike carbon treatment improved hardness Knoop and reduced the flexibility of the Irri Black ultrasonic tip, improving its time to fracture under oscillatory motion compared with the nontreated E1-Irrisonic tip.

Microstructure Evaluation of the Potential of Additive Manufactured Dissimilar Titanium-Aluminum Alloys.

Pure titanium (Ti) ERTi-2 was accumulated on an aluminum (Al) alloy ER5356 component via wire and arc additive manufacturing. The effect of processing parameters, mainly the input heat per unit length, on Ti/Al components was investigated. The microstructure of the Ti deposited layer and the Ti/Al reaction layer was analyzed using optical microscopy, scanning electron microscope, energy-dispersive spectroscopy, and an X-ray diffractometer. The fabrication of the surface layer equivalent to pure Ti as the used wire or Ti-Al alloy on the Al alloy components was achieved under low and high input heat conditions, respectively, although the Ti/Al components had low joinability and cracks at the reaction layer. Finally, the potential of additive-manufactured Ti/Al components with reference to our results and previous reports was discussed.

Отработка методики плазменной резки меди марки М1, алюминиевого сплава Д16Т и титанового сплава ОТ4-1 с использованием плазмотрона с обратной полярностью

Introduction. An important area of research in the field of plasma metal cutting is obtaining a metal cut face characterized by minimal roughness and geometric deviations. It is also important to minimize changes in the structure of the metal under the cutting surface caused by the temperature effects of the plasma jet, including the formation of dross. The solution to the problem of obtaining a quality cut is to optimize the parameters of the cutting process. The plasma arc current and voltage, cutting height and cutting speed are considered to be the main parameters that determine cut quality. However, insufficient attention has been paid to the processes of plasma metal cutting of thicknesses above 20 mm due to the limitations associated with the operation conditions of plasma torches with direct polarity currents. Accordingly, for cutting large thicknesses, the use of a plasma torch operating on currents of reverse polarity seems promising. The aim of this work is to develop the technique of plasma cutting of copper, titanium and aluminum alloy sheets up to 40 mm thick using a plasma torch operating on currents of reverse polarity. Results and discussion. Investigations show that for cutting aluminum alloy (Al 90.9–94.7 %; Cu 3.8–4.9 %; Mg 1.2-1.8 %; Mn 0.3–0.9 %) and titanium alloy (Ti 94.33–97.5 %; Al 1.5–2.5 %; Mn 0.7–2.0 %) it is possible to regulate the cutting speed in a wide range, while for rolled copper (Cu ≥99.96 %) and aluminum alloy with thickness of 40 mm the range of cutting speed regulation is rather narrow. While for aluminum alloy due to excessive precipitation of alloying elements from the solid solution in the heat-affected zone decrease of microhardness is observed, for titanium alloy the microhardness growth due to material hardening is characteristic. Changing the cutting mode parameters allows receiving more homogeneous macrogeometry of a cutting surface, smaller depth of a zone of melting of a material and a heat-affected zone and smaller changes of mechanical properties of a material in a zone of a cut. For the titanium alloy, almost all of the cutting modes used are close to optimum. For alloy aluminum and copper the modes providing the best cutting quality in the considered range of parameters are determined. According to the results of the work it can be concluded that plasma cutting on reverse polarity currents is effective for cutting rolled products of large thicknesses, but the technique requires further development in order to improve the quality of the resulting cut.

Research on the lightweight structural optimization design of the front collector of the polymetallic nodule miner

The polymetallic nodule miner (PNM) is prone to sink on deep-sea soft sediments due to its large weight, resulting in decreased mobility performance and mining efficiency. As a heavy-duty mechanism of the PNM, the weight reduction of the front collector (FC) can improve this issue. In this study, the lightweight optimization design of the FC was presented. The hydrodynamic forces on the FC were calculated by computational fluid dynamics (CFD) simulation and fully mapped as nodal loads into the finite element method (FEM) model to obtain the structural performance of the FC in the deep sea. Aluminum alloy and titanium alloy were applied in the FC, and then the structures of the FCs with different materials were optimized using the response surface method (RSM) surrogate model. After the lightweight design, the structure-optimized FC with steel, FC with aluminum alloy, and FC with titanium alloy were lightened by 4.15%, 19.22%, and 14.67%, respectively, while their structural performances were improved. A comparison of the optimization effects revealed that the application of aluminum alloys and further structural optimization comprises the optimal solution. The research conducted in this study provides a useful reference for the structural design of the FC.

Laser-processed antiadhesive bionic combs for handling nanofibers inspired by nanostructures on the legs of cribellate spiders.

Nanofibers are drawing the attention of engineers and scientists because their large surface-to-volume ratio is favorable for applications in medicine, filter technology, textile industry, lithium-air batteries, and optical sensors. However, when transferring nanofibers to a technical product in the form of a random network of fibers, referred to as nonwoven fabric, the stickiness of the freshly produced and thus fragile nanofiber nonwoven remains a problem. This is mainly because nanofibers strongly adhere to any surface because of van der Waals forces. In nature, there are animals that are actually able to efficiently produce, process, and handle nanofibers, namely cribellate spiders. For that, the spiders use the calamistrum, a comb-like structure of modified setae on the metatarsus of the hindmost (fourth) legs, to which the 10-30 nm thick silk nanofibers do not stick due to a special fingerprint-like surface nanostructure. In this work, we present a theoretical model of the interaction of linear nanofibers with a sinusoidally corrugated surface. This model allows for a prediction of the adhesive interaction and, thus, the design of a suitable surface structure to prevent sticking of an artificially nonwoven of nanofibers. According to the theoretical prediction, a technical analogon of the nanoripples was produced by ultrashort pulse laser processing on different technically relevant metal surfaces in the form of so-called laser-induced periodic surface structures (LIPSS). Subsequently, by means of a newly established peel-off test, the adhesion of an electrospun polyamide fiber-based nonwoven was quantified on such LIPSS-covered aluminium alloy, steel, and titanium alloy samples, as well as on polished (flat) control samples as reference and, additionally, on samples with randomly rough surfaces. The latter revealed that the adhesion of electrospun nanofiber nonwoven is significantly lowered on the nanostructured surfaces compared with the polished surfaces.

Recent Advances in the Equal Channel Angular Pressing of Metallic Materials

Applications of a metallic material highly depend on its mechanical properties, which greatly depend on the material’s grain sizes. Reducing grain sizes by severe plastic deformation is one of the efficient approaches to enhance the mechanical properties of a metallic material. In this paper, severe plastic deformation of equal channel angular pressing (ECAP) will be reviewed to illustrate its effects on the grain refinement of some common metallic materials such as titanium alloys, aluminum alloys, and magnesium alloys. In the ECAP process, the materials can be processed severely and repeatedly in a designed ECAP mold to accumulate a large amount of plastic strain. Ultrafine grains with diameters of submicron meters or even nanometers can be achieved through severe plastic deformation of the ECAP. In detail, this paper will give state-of-the-art details about the influences of ECAP processing parameters such as passes, temperature, and routes on the evolution of the microstructure of metallic materials. The evolution of grain sizes, grain boundaries, and phases of different metallic materials during the ECAP process are also analyzed. Besides, the plastic deformation mechanism during the ECAP process is discussed from the perspectives of dislocation slipping and twinning.

Effect of loading rate and height–diameter ratio on compression characteristics of aviation alloys

Loading rate and height–diameter ratio are important factors affecting mechanical properties of materials. In this paper, the effects of the two factors on the stress–strain curves and section deformation characteristics of titanium alloy and aluminum alloy were compared by uniaxial compression tests. The gray correlation coefficient between compressive strength and loading rate, height–diameter ratio, and high compression ratio of the two alloys was calculated by using the gray correlation theory, and multiple regression models of compressive strength of the two alloys were established based on the least squares method. The results show that ( i) the gray correlation coefficient of the two alloys is greater than 0.6, indicating that loading rate and height–diameter ratio have obvious effects on the compressive strengths of aluminum alloy; ( ii) of loading rate and height–diameter ratio, loading rate has more significant effect on compressive strength; and ( iii) the correlation coefficient of the regression model of titanium alloy compressive strength is 0.9, which is higher than that of the corresponding model of aluminum alloy (0.65), indicating that the reliability of the regression model of titanium alloy is higher than that of aluminum alloy, and the established model can better predict the uniaxial compressive strength of titanium alloy.

Influence of Titanium Additions to Aluminum on the Microhardness Value and Electrochemical Behavior of Synthesized Aluminum-Titanium Alloy in Solutions of HCl and H3PO4

The effect of Ti content in various concentrations as an alloying element with Al on both microhardness and crystallization structure of aluminum–titanium alloys was studied, utilizing x-ray diffraction (XRD) and a scanning electron microscope (SEM). To study the electrochemical and corrosion performance of Al and its investigated alloys in 0.5 M solutions of HCl and H3PO4, two different techniques were used: extrapolation of Tafel plot and electrochemical impedance spectroscopy (EIS). Tafel plots and EIS revealed a similar trend. Generally, the rate of corrosion of the alloys was higher than that of Al. This investigation exhibited that the corrosion of Al alloying with Ti increased with an increase in both Ti content and temperature, which is due to reducing the growth of oxide film on the surface. Changes in the standard values of both entropy (ΔS) and enthalpy (ΔH), in addition to apparent activation energy (Ea) of corrosion processes of Al and its alloys in HCl and H3PO4, were evaluated. The evaluated data indicated negative values of ΔS, while the values of ΔH were positive. Besides, the decrease in ΔH value with the increase of Ti content in the alloy revealed that the dissolution of the studied alloys was fast. The positive values of ΔH were accompanied by an endothermic process. On the other hand, the activation energy (Ea) was decreased as a result of Al alloying with Ti in the two mentioned acids. Those results were supported by the corrosion current density (icorr.) and impedance parameters. By comparing the data obtained for both HCl and H3PO4 in all investigated electrodes, the corrosion current density (icorr.) in H3PO4 was lower than that in HCl. Such behavior can be ascribed to the aggressive attack of Cl¯ ions on the surfaces of the investigated electrodes, leading to pits formation.

Simulation-based parameter optimization of friction forge riveting for AA6061-T6 and TA2 with TA2 titanium rivet

Friction forge riveting (FFR) has been developed for connecting titanium alloy and aluminum alloy with titanium rivets, although the weak formation of rivet during this process is still a key issue that should be solved properly. In this study, a thermomechanical coupling model was established in DEFORM-3D based on the practical thermal cycle of rivet during FFR process. Furthermore, the temperature and stress fields were also revealed in detail. The results showed that by reducing the loading speed of friction tool in the first 1 mm stroke, the flash defects and root defects caused by insufficient filling of the driven rivet head can be effectively avoided, and the joint mechanical performance including strength and service life was also improved. With the optimized FFR parameters, perfect joints were obtained without surface flash, holes or tunnels.

Milling of Three Types of Thin-Walled Elements Made of Polymer Composite and Titanium and Aluminum Alloys Used in the Aviation Industry.

The machining of thin-walled elements used in the aviation industry causes may problems, which create a need for studying ways in which undesirable phenomena can be prevented. This paper presents the results of a study investigating face milling thin-walled elements made of titanium alloy, aluminum alloy and polymer composite. These materials were milled with folding double-edge cutters with diamond inserts. The results of maximum vertical forces and surface roughness obtained after machining elements of different thicknesses and unsupported element lengths are presented. The results of deformation of milled elements are also presented. The results are then analyzed by ANOVA. It is shown that the maximum vertical forces decrease (in range 42–60%) while the ratio of vertical force amplitude to its average value increases (in range 55–65%) with decreasing element thickness and increasing unsupported element length. It is also demonstrated that surface roughness deteriorates (in range 100% for aluminum, 30% titanium alloy, 15% for CFRP) with small element thicknesses and long unsupported element lengths. Long unsupported element lengths also negatively (increasing deformation several times) affect the accuracy of machined elements.

Optimization of friction stir spot welding between aluminium alloys and titanium alloy by the Taguchi method

This research investigated the shear force of dissimilar welding processes between Ti-4V-6Al titanium alloys and Al5052 aluminium alloy by friction stir spot welding (FSSW). The Taguchi L9 orthogonal was used in the experimental design. The welding process parameters are rotation speed (A), feeds (B), and dwell time (C). ANOVA analyzed the S/N ratio of shear force to determine the optimal parameters for statistically significant factors. In addition, analyze for process parameters on the response and the level of the indispensability factor, as well as predict and regression model for optimal tensile strength. The investigation revealed that the optimum parameters were A2B2C3, and the shear force was 2.84 kN. Furthermore, the experiment found that rotation speed and dwell time significantly on the shear force since both factors had a P-value of less than 0.05 (p ≤ 0.05). Therefore, rotation speed and dwell time parameters are the most critical parameters in the process at a 95% confidence level. On the other hand, an investigation of feeds demonstrates an insignificant shear force of the weld due to a P-value above 0.05 (p ≥ 0.05).

Experimental Analysis of Circular Milling for Material Identification in Aerospace Industry

In the airplane design, thousand holes should be manufactured by machining leading this process in the first place for process optimization. Recently, the stack materials used in this application are sheet layers of Titanium alloy, Aluminum alloy and CFRP, which normally are machined under different cutting conditions. There are two main solutions when drilling stacks: using the more conservative ones or changing the parameters for each layer. In orbital drilling the forces are lower, with better quality but with longer machining time, compared to drilling, allowing the measurement and control of the process. Smart machining techniques can be applied for recognising and adapting the cutting parameters in real time, depending on a database for decision-making. In this paper, a technique is proposed to identify the cutting material based on the cutting and feed components of the machining force in a circular milling process. Experiments consist of machining separately Titanium and Aluminium alloy workpieces in a similar range of cutting speed and feed, measuring forces and the position of the cutting tool (X,Y, SP) using the machine-tool data. The results show that it is possible to identify the materials using the calculated tangential and radial force components in the tool referential frame because the values of specific cutting and feed force are significantly different for each material. An specific force map is used as a signature to distinguish the materials in real time machining which can be used for orbital drilling in the next step of the research.

Hot spot stress and fatigue strength assessment of marine 5059 aluminum alloy reinforced structure considering welding effect

AbstractWith the increasing demand for lightweight ships, marine alloy materials such as aluminum alloy and titanium alloy are widely used; 5059 aluminum alloy is considered as an ideal steel for hull structure because of its good mechanical properties and corrosion resistance. The influence of welding residual stress and welding deformation must be considered in fatigue evaluation of thin‐plate welded structures. However, due to the more complex welding deformation and residual stress distribution of thin‐plate welded structures, the fatigue evaluation of thin‐plate welded structures is challenged. In this paper, a series of fatigue tests of actual reinforced T‐shaped welded joints are carried out, and the accurate welding deformation and residual stress are obtained by numerical simulation. Finally, taking welding deformation and residual stress as initial conditions, the hot spot stress S‐N curves of typical joints are modified by hot spot stress method.

A Review of Low‐Plasticity Burnishing and Its Applications

Low‐plasticity burnishing (LPB) has been widely used in various industries. In the LPB process, when the ball moves on the material surface, plastic deformation or cold working occurs in the burnished region. Through this process, not only can LPB improve the surface integrity of metallic material components by replacing polishing in some situations, but it can also improve fatigue performance thanks to the low work hardening and the beneficial compressive residual stress (CRS). So far, extensive research has demonstrated the influence of the LPB process on surface integrity and service performance of different metallic materials, such as titanium alloys, aluminum alloys, magnesium alloys, nickel‐based superalloys, stainless steels, and carbon steels. Recent years have witnessed many innovative LPB processes and novel applications. Herein, the working principle of the LPB process is first restated. Following that, how LPB strengthens the material surface and thereby influences the mechanical performance, including the surface quality, residual stress, microstructure, microhardness, fatigue, and wear performance, is reviewed. Furthermore, the difference of surface‐strengthening effect among LPB and other surface mechanical strengthening processes is compared. Finally, the current challenges to LPB are discussed and some suggestions on its development directions are put forward.

Ballistic impact experiments of titanium-based carbon-fibre/epoxy laminates

In this paper, high-velocity impact resistance of lightweight laminates with multi-layers of carbon-fibre/epoxy laminates sandwiched by two titanium alloy skins and aluminium alloy skins was extensively investigated by experiments with a total of 48 impact tests conducted. The ballistic limit of the titanium-based carbon-fibre/epoxy laminate was estimated to be between 241.6 m/s and 257.1 m/s. Impact velocity governed energy absorption and the corresponding damage modes were characterised and identified. The influence of fibre metal laminates configuration on the impact resistance was then experimentally investigated at a fixed impact velocity with full penetration in ten types of laminates. The results also showed that thicker skin and higher number of fibre layers favoured the specific energy absorption in the tested matrix.

Quasi-static mechanical properties of origami-inspired cellular metamaterials made by metallic 3D printing

Cellular mechanical metamaterials based on origami folded structures have attracted much attention due to their high designability in the mechanical properties. While origami cellular metamaterials (OCMs) made of plastics via 3 D printing have been studied extensively, those fabricated by metallic 3 D printing are relatively rare. This article presents a systematical experimental and numerical study on the quasi-static mechanical properties of 3 D-printed metallic OCMs based on various origami configurations and revealed the relationship between their key design parameters and mechanical performance. First, the OCM specimens based on the Miura pattern were fabricated using a metallic 3 D printing method, and compression tests were carried out to obtain their mechanical responses. The experiment results showed that the OCM specimens made from stainless steel exhibited large elastoplastic deformation, whereas early fracture of the material occurred in the aluminum alloy and titanium alloy specimens, and those with smaller cell size and wall thickness showed enhanced mechanical performance. Second, the FE modeling method for the metallic OCMs was developed and validated with the experiment data. Parametric studies on the compressive behaviors of metallic OCM models based on the two-stage Miura, perforated Miura, graded Miura, and cube pipe structures were then conducted. The relationships between the key geometric parameters and mechanical performance of various OCM models were disclosed. This work can provide a practical guide for the design and fabrication of 3 D-printed metallic OCMs.

Farklı Malzemelerle Biyel Kolunun Deformasyon ve Gerilme Analizi

Today's vehicle technology is based on internal combustion engines. However, hybrid models have been introduced to the market in recent years. The purpose of these models is to reduce fuel consumption. Hybrid vehicles are based on the principle of simultaneous operation of an electric and gasoline engine. According to this working principle, it is predicted that the use of internal combustion engines will continue for a long time. For these reasons, studies on fossil fuel-powered engines are still ongoing and are expected to continue in the future. Appropriate design and material selection come to the fore in studies on the engine and the machine elements that make up the engine. Therefore, it is the design and the suitability of the material used and the weight that should be considered in the production of the parts that make up the engine. The most important part to be considered while designing the engine elements is to maximize the effect of the engine on the vehicle, namely the performance, and to carry out the necessary studies to reach this level. For this, the design of the elements that make up the engine and the connecting rod, which is the subject of this study, is of great importance. Although the design factor in a connecting rod alone, which is a part of the engine and is expected to withstand the stresses formed in the engine, does not seem to be effective, the performance of the engine in terms of design and therefore weight is also affected by this situation. In this study, necessary analyzes were made in terms of performance by designing the connecting rod. Using four different materials; aluminum alloy, titanium alloy, steel alloy and cast iron, connecting rods designed using an ANSYS Workbench software were analyzed. In the analysis, studies on stress and deformation were carried out. As a result, it was concluded that the aluminum alloy material is the most suitable design in terms of both weight and material supply.

Process-induced evolution of prismatic dislocation loop and its effect on mechanical properties

Titanium aluminum alloy is widely used in aerospace, automotive engines and other fields, the attention of microstructure and mechanics of the machined workpiece can make it have better service performance. This paper constructs a molecular dynamics model that better fits with the actual nano-cutting of single crystal γ-TiAl alloy. The formation of the sub-surface defect layer in the nano-cutting process is analyzed, and the evolution mechanism of the material sub-surface prismatic dislocation loop is discussed in detail. In addition, the nanoindentation simulation is carried out on the surface of the material with prismatic dislocation loop structure to study the effect of process-induced sub-surface defect structure on the mechanical properties of the material. The simulation results show that the existence of Stair-rod dislocation in the prismatic dislocation loop hinders the slip of stacking fault. The nanoindentation process will release the residual stress in the material and make the material have a certain degree of elastic recovery. The original defect structure will increase the hardness of the material, which verifies the work hardening phenomenon of the machined surface caused by the internal defects of the material.

Coupled Heat Transfer Properties of Aluminum/Titanium Alloy Plates With Kerosene Active Cooling

Abstract Active cooling is an effective thermal protection method for plates under high thermal loading. In this paper, characteristics of coupled heat transfer of aluminum alloy and titanium alloy plates with kerosene active cooling are studied numerically and experimentally. The effects of cooling channel spacing as well as the inlet parameters of kerosene on the maximum temperature and temperature uniformity of the plate are investigated with varied heat fluxes. Besides, the thermal resistance and flow resistance of kerosene cooling are also analyzed. The experimental results show that the 2a12-type aluminum alloy plate can be cooled to a maximum temperature of 460 K with kerosene cooling under a mass flowrate of 24.7 g/s and heat flux of 6–11 kW/m2. The numerical results show that the maximum temperature is mainly affected by the channel spacing and heat flux. Compared to the titanium alloy plate, the aluminum alloy plate is more likely to be affected by the coolant mass flowrate. In addition, the conductive thermal resistance of aluminum alloy plates is 0.0017–0.0079 m2 K/W and is 0.015–0.073 m2 K/W for titanium alloy plates. For both materials, conductive thermal resistance dominates the total thermal resistance of plates with active cooling.