Wide Applications In Aerospace Industries Research Articles

Effect of aging treatment on the microstructure and properties of cold rolled Ti-10V-2Fe-3Al alloy

As a typical metastable titanium alloy with high strength and toughness, Ti-10V-2Fe-3Al titanium alloy has found wide applications in aerospace industry to replace forging steel components for light weight, long service life and high reliability. In the present study the microstructure evolution and mechanical properties of cold rolled Ti-10V-2Fe-3Al alloy undergoing aging treatment were characterized by optical microscopy, X-ray diffraction, transmission electron microscopy and mechanical testing, in attempt to understand the relationship between the microstructural evolution and aging treatment temperature and time. It is revealed that the secondary α phase had a very short propagation time to nucleate, and holding 5 min could give rise to the transformation from β phase to secondary α phase when cold rolled alloy suffered from aging at 550°C. This could be attributed to the large amounts of dislocations and grain boundaries by cold deformation, which provide nucleation sites for α phase. Increasing aging time could accelerate the transformation from β phase to secondary α phase. With aging at 550°C for 30 min, a large amount of fine secondary α phase formed, offering a good combination of strength and ductility. With increasing aging time the coarsening secondary α phase led to a decrement of strength of the alloy.

Investigation of Abrasive Aqua Jet Hole Making (AAJHM) parameters using desirability analysis on Inconel-625 space alloy

Inconel-625 is one of the high-strength space alloys with wide applications in aerospace industries and corrosion resistance environments. The applications of Inconel-625 material require blind holes with adequate quality characteristics. In the conventional method, the hole-making on Inconel-625 is difficult due to its mechanical behaviour. The abrasive aqua jet machining process can cut hard and brittle materials among various unconventional machining processes. This work proposes to determine the ideal values of process parameters to generate quality holes on Inconel-625 space alloy by optimizing the abrasive aqua jet hole-making process parameters using a desirability analysis. Abrasive jet pressure (AJP), gap distance (Gdi), traverse speed (Tspeed), and abrasive mixture (Abrmix) of garnet and silicon carbide were identified as potential process variables. The quality hole surface is discussed through surface roughness (SR), erosion rate (Er), circularity error (CI), and cylindricity error (CY). The experimental investigation discloses that SR, CI, and CY decreased by 27.35 %, 56.23 %, and 42.56 %, and Er increased by 32.83 % when the AJP reached its higher value of 300 MPa. According to desirability analysis, the optimal level of machining parameters for numerous solutions is AJP = 300 MPa, Gdi = 1 mm, Tspeed = 96 mm/min, and Abrmix = 100%SiC (AJP-2, Gdi-2, Tspeed-1, Abrmix-2). The ANOVA investigation revealed that AJP was the most contributed parameter, trailed by Abrmix as 100%SiC. SEM and 3D images were used to analyze the surface topography of the hole surface of Inconel-625.

Predicting hydrogen microporosity in long solidification range ternary Al-Cu-Li alloys by coupling CALPHAD and cellular automata model

Aluminum-lithium alloys have wide applications in aerospace industries in the 21st century but their manufacturing is extremely difficult due to the 10 times more equilibrium hydrogen concentration in the liquid than the solubility limit in traditional Al alloys (0.036 mL/100gSTP). The reduction of solubility from liquid to solid by 95% leads to hydrogen porosity being hard to control. In this work, a three-dimensional multicomponent cellular automaton (CA) model is coupled with CALPHAD calculations to simulate the nucleation and growth of hydrogen porosity and its interaction with surrounding dendritic structures during the solidification of Al-Cu-Li alloys. By quantifying the effects of hydrogen concentration, cooling rate, and Li content, it was found the solidification conditions can effectively reduce porosity size. To validate the model, X-ray computed tomography (XCT) has been used to obtain not only the size but also the morphology of porosity as a function of cooling conditions. It was found that porosity grows elongated and tortuous shape at slow cooling rates between columnar dendrites, filling up the empty spaces of secondary arms, while it tends to be dispersed spherical shape when its surrounding grains are refined to equiaxed structures at high cooling rates.

Fundamental study on CNC polishing method with inner channel liquid supply

The various optical components have wide applications in aerospace industries. In the manufacturing process of optical components that are made of optical glass materials, the main challenges still are how to ensure the high requirements in dimensional accuracy and surface quality. In this paper, the CNC polishing method with inner channel liquid supply (ICLS) is proposed to polish glass materials based on the chemical mechanical polishing mechanism. The comparative experiment with both inner and external liquid supply was designed, and it is found that the successive and steady material removal rate (MRR) can be achieved by using the proposed polishing method. Then, the effect of polishing pressure, tool rotation speed, and polishing time on polishing quality was analyzed with single-factor experiments. Finally, the optimal polishing parameters were obtained with the orthogonal experiment. The results show that the average surface roughness is reduced from 238.16 to 1.34 nm, and the nanoscale super-smooth surface is achieved, which proves the feasibility of the CNC polishing method with ICLS.

Sliding wear behaviour of CP titanium laminates produced by large strain extrusion machining

Titanium sheets find their wide application in aerospace industry. Rolling process is commonly used for making these sheets. Inducing large amount of strain in high strength materials with HCP structure such as Magnesium and Titanium alloys makes rolling a multistage process. Moreover, controlling crystallographic texture in multistage deformation processes is also very critical. To overcome these limitations, in present research attempt large strain extrusion machining (LSEM) process is used to produce laminates from CP titanium sheets with controlled microstructure in a single continuous operation. These CP Ti laminates are produced at different strain rate. Microstructural analysis and hardness measurement of fabricated laminates are carried out using scanning electron microscopy and Vickers microhardness tester respectively. Roughness tester is used for roughness measurement. X-Ray diffraction is used for deformation analysis of the laminates. Sliding wear tests on produced laminates are performed using tribometer. Hardness measurement revealed a ~25–52% increase in hardness value in fabricated laminates as compared to bulk material. This increase in hardness may be attributed to grain refinement resulted from high deformation induced by LSEM process. The surface roughness of fabricated laminates decreased with increase in strain rate. Wear rate analysis of the samples have shown improved wear performance of laminates fabricated by the process in comparison to bulk material. Wear rate is observed to be lower in direction perpendicular to laminate formation direction.

Investigations on femtosecond laser-induced surface modification and periodic micropatterning with anti-friction properties on Ti6Al4V titanium alloy

Titanium alloys have a wide application in aerospace industries as it has greater strength and low density, but it has poor tribological properties. To improve its friction and wear performance, in present work, a femtosecond laser is used to directly irradiate the Ti6Al4V titanium alloy surface in air conditioning, which results in localized ablation and the formation of periodic microstructures but also a strong pressure wave, propagating the material inside. Through the optimization of processing parameters, surface modification and periodic micropatterning with effective anti-friction properties were successfully induced on the surface. After a treatment of femtosecond laser-induced surface modification (FsLSM), the surface microhardness was improved by 16.6% and compressive residual stress reached −746 MPa. Besides, laser-induced periodic surface structures (LIPSS) with a titanium oxide outer coating were fabricated uniformly on the titanium alloy surface. Rotary ball-on-disk wear experiments revealed that the average coefficient of friction (COF) and wear mass loss of the specimen with FsLSM treatment were largely reduced by 68.9% and 90% as compared to that of untreated specimens, respectively. It was analyzed that the reason for the remarkable wear resistance was attributed to the comprehensive action of the generation of LIPSS, the titanium oxide outer coating, high amplitude compressive residual stress and gradient grain size distribution on the subsurface during the laser surface treatment. Since the findings here are broadly applicable to a wide spectrum of engineering metals and alloys, the present results offer unique pathways to enhancing the tribological performance of materials.

Experimental Investigation on machining of Titanium Alloy (Ti 6Al 4V) and Optimization of its Parameters using ANN

Engineering industries continuously face challenges in maintaining a consistently high product quality in terms of dimensional accuracy and surface finish, sustaining a high production rate, and economical processing of materials by minimizing cutting tool wear, rejections and rework. In this study, turning of Titanium alloy (Ti-6Al-4V) has been taken up for optimizing the material removal rate and surface finish, the reason being its wide application in aerospace industry. Cutting speed, feed rate and depth of cut were assigned as the input variables. Design of experiments based on Taguchi technique and L27 orthogonal array was employed to analyze the experimental data and the predicted values. Analysis of variance was used for identify the input parameter exerting maximum influence on surface finish and MRR. It was observed that the experimental results are in good agreement with the predicted values from DOE and multilayered feed forward Artificial Neural Network employed to predict process responses. The optimal values of the input and output parameters are tabulated. DOI: http://dx.doi.org/10.5755/j01.mech.24.4.20251

Modeling and Analysis of CNC Milling Process Parameters on Al3030 based Composite

The machining of Al3030 based composites on Computer Numerical Control (CNC) high speed milling machine have assumed importance because of their wide application in aerospace industries, marine industries and automotive industries etc. Industries mainly focus on surface irregularities; material removal rate (MRR) and tool wear rate (TWR) which usually depends on input process parameters namely cutting speed, feed in mm/min, depth of cut and step over ratio. Many researchers have carried out researches in this area but very few have taken step over ratio or radial depth of cut also as one of the input variables. In this research work, the study of characteristics of Al3030 is carried out at high speed CNC milling machine over the speed range of 3000 to 5000 r.p.m. Step over ratio, depth of cut and feed rate are other input variables taken into consideration in this research work. A total nine experiments are conducted according to Taguchi L9 orthogonal array. The machining is carried out on high speed CNC milling machine using flat end mill of diameter 10mm. Flatness, MRR and TWR are taken as output parameters. Flatness has been measured using portable Coordinate Measuring Machine (CMM). Linear regression models have been developed using Minitab 18 software and result are validated by conducting selected additional set of experiments. Selection of input process parameters in order to get best machining outputs is the key contributions of this research work.

Hydride formation during cathodic charging and its effect on mechanical properties of a high Nb containing TiAl alloy

Due to their high specific strength and modulus at evaluated temperature, high Nb containing TiAl alloys have attracted extensive interest as prospective structural material for aerospace. However, low ductility as well as long-term expose to hydrogen still impedes its wide application in aerospace industries. This work focuses on hydrides' formation during cathodic charging and its effect on microstructure and mechanical properties of a high Nb containing TiAl alloy with the composition of Ti45Al8.5Nb-(W, B, Y). A hydride (TiAl)Hx with tetragonal crystal structure has been observed in alloys charged at 20, 100 and 500 mA/cm2 for 24 h. With the increase of current intensities, the thicknesses of hydride layer are around 2, 6 and 20 μm in samples charged at 20, 100 and 500 mA/cm2 for 24 h, respectively. The hydride layer exhibits loose and polyporous structure. The hydrogen diffusion coefficient of the alloy charged at 20 mA/cm2 for 24 h has been evaluated to be 6.33 × 10−16 m2/s by the nano-hardness from the distribution of the hydride layer. The tensile strengths of the alloys charged at 20, 100 and 500 mA/cm2 are 485, 476 and 405 MPa, while the strains are 0.699, 0.659 and 0.558, respectively.

Optimal cutting conditions towards sustainable machining when slot milling aluminium alloy

Energy used in manufacturing has to be reduced in order to cut down carbon emission derived from energy generation. Optimising cutting parameters and selecting a proper cutting environment reduces energy consumption contributing to a sustainable manufacturing. The research reported herein is focused mainly on searching for an optimum combination of cutting parameters and cutting environment to minimise energy consumption when milling aluminium alloys. The selection of this workpiece material was based on its wide applications in aerospace industry basically due to its high corrosion resistance and high strength-to-weight ratio, characteristics. The experiments were conducted on a Siemens 840D Bridgeport Vertical Machining centre 610XP2. The results show that the cryogenic cutting environment is the optimal environment in terms of power consumption and surface roughness value to conduct the milling of a 6082-T6 aluminium alloy under the selected cutting parameters.

A Study on Response of a Contoured Composite Panel with Co-cured Stiffeners Under Transient Loading

Composite materials are emerging to be the best applied materials for aerospace applications. With rapid improvement in computational facilities, it is now possible to design the best composite lay up for a particular kind of application. This paper presents the development of a Finite Element model of a contoured composite panel with co-cured stiffeners using Finite Element Simulation. Commercial package ANSYS 15.0 is used for this study. Such half contoured panels find wide application in Aerospace industry. The panel is hinged at one of the ends and dynamically loaded at the other end over a relatively small surface area by transverse load. The response of the panel is observed for variation in stresses, deflections and failure criteria. The panel is expected to rotate about the hinge point by 4° from the initial point. The transient response of the composite panel has been observed for expected load and two test load cases and results reported in this paper. Analysis has become useful input for the design of panel.

Optimization of Face Milling Parameters for Material Removal Rate and Surface Roughness on Inconel 718 using Response Surface Methodology and Genetic Algorithm

Face milling operation is used to remove the materials in the form of chips on the work piece surface in order to improve the surface quality. It is one of the important machining processes for achieving high flatness and low surface roughness of prismatic parts. So, this work investigates the parameters influences on Material Removal Rate (MRR) and Surface Roughness (SR) in newer material Inconel 718. Inconel 718 has wide applications in aerospace industry, particularly in the hot sections of gas turbines, due to their high-temperature strength and high corrosion resistance. Because of these properties, obtaining the better surface quality will be the challenging one. However, the milling parameters such as spindle speed, feed rate and depth of cut decide the productivity and the quality of part in face milling. Hence, this work aims to formulate the relationship between input and response variables for improving the face milling performances. For identifying the effects of input parameter and interaction effect of process parameter on MRR and SR, the Response Surface Methodology (RSM) is used. Regression analysis is conducted for building empirical model. The performance of developed regression models are verified with experimental results. Verification results show the developed models have best agreement with experimental results. The developed models are used for achieving the best input parameters by using Genetic Algorithm (GA). Finally, the results of GA have good agreement with experimental results.

Interfacial reaction behavior and mechanical characterization of ZrO2/TC4 joint brazed by Ag–Cu filler metal

Reliable brazing of ZrO2 ceramic to TC4 alloy is crucial for the wide applications in aerospace industries and biomedical devices. However, the brazing mechanism of ZrO2 ceramic has not been investigated systemically compared to Al2O3 and Si3N4 ceramics. The nature of the reaction products adjacent to ZrO2 ceramic still remains somewhat elusive. In this study, ZrO2 ceramic and TC4 alloy was successfully brazed with inactive AgCu filler metal. The interfacial microstructure of the joints was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effect of brazing temperature on the microstructure and mechanical properties of the joints were investigated in details. The results revealed that Cu3Ti3O+TiO layers were formed adjacent to ZrO2 ceramic while Ti–Cu IMCs layers were formed at TC4 substrate. With increasing brazing temperature, the thickness of Cu3Ti3O+TiO layers and Ti–Cu IMCs layers increased obviously. The hardness and elastic modulus of reaction phases were characterized by nano-indentation to reveal the plastic deformability. The highest shear strength of 52.2MPa was achieved when brazed at 870°C for 10min.

Direct current resistance testing methods of carbon fibre reinforced polymer

An experiment platform was established for direct current resistance testing methods of carbon fibre reinforced polymer composites in this paper. Drastic differences have been found in the volume resistance of carbon fibre reinforced polymers between the theoretical values and testing values obtained with a classic three-electrode testing method for solid dielectric materials. Thus, on the basis of the experimental circuit and structures of carbon fibre reinforced polymers, an improved three-electrode testing method was put forward. The experimental results, which reflect the electric characteristics, surface coating materials and internal layer structures of carbon fibre reinforced polymers were subsequently obtained and can be well explained by the inferred conduction model, in which the electric field extension and surface current effect were considered comprehensively. This work provides a theoretical support for further research of electric characteristics, thermal degradation and weight loss of carbon fibre reinforced polymers and also lays a solid foundation for its wide applications in aerospace industries.

Experimental Study on Surface Roughness and Residual Stress by End Milling 69111-Stainless Steel

69111-stainless steel has wide applications in aerospace industry due to its comprehensive performance. However, its machining properties are not well studied due to the short using history in product components. In this study, a series of end milling experiments were conducted to characterize surface integrity at various milling conditions. The experimental results have shown that the milled surface roughness value increases with increased feed and cutting speed, while decrease with axial depth-of-cut (DoC) , and presents an inflexion with the radial DoC, with a rang of 0.7~1.7μm. Residual stress determined by the coupling effect of mechanical and thermal deformations varies differently with the increased cutting parameters.

The Applications of SPF/DB Combined with Welding Technologies

Superplastic forming and diffusion bonding (SPF/DB) processes have been growing mature and titanium SPF/DB components have found wide application in aerospace industry. With the development of industrial SPF/DB technology, the size of SPF/DB components become bigger and bigger, and the shapes of components become more complex. However, the component sizes are limited by equipments, dies and the size of sheet. SPF/DB combined with welding technologies could be one of the possible solutions to form larger and more integrated structures due to many advantages compared with conventional process. This paper studied the combination processing of SPF and other welding methods besides diffusion bonding, such as electron beam welding and laser beam welding, and explained the experiments performed in different processes, including SPF after welding plate and welding plate after SPF. The results show that the material exhibits both reasonable formability and excellent mechanical properties. Application samples such as covers were manufactured by the combination processing. Furthermore, prospects of the combining technology were discussed at the end of paper.

FURTHER PROBLEMS AFFECTING THE PRODUCTION OF ELLIPTICAL HOLES BY ECM

RCM has found wide applications in aerospace industries. However, tool design in ECM is still a problem which delays the use of this process. This paper has fccused attention on some of the problems that are to be studied before it would be possible to obtain an analytical design of toolings for ECM. Furthermore, this. paper has emphasized that each component in ECM presents its own particular problems and each must be treated on its own merits as has been shown through producing the elliptical hole shape. Inequality of electrolyte distribution, different electrolyte path lengths and variations in current density have been found to be the main features that characterize the nature of the elliptical hole shape by ECM. Resistance model technique has been suggested and modified to use for analysis of the elliptical hole shape. A parametric study of the process which highlights certain guidelines for ECM tooling designer is also presented. Experimental results have revealed significant variations in the resultant side gap length at major and miner diameterS of the tool. The experimental tests have been in agreement with the present analysis. Further, resistance model technique has proved its validity for use in evaluating the power consumption in ECM.