Esther T. Akinlabi

Bio: Esther T. Akinlabi is an academic researcher from Covenant University. The author has contributed to research in topic(s): Ultimate tensile strength & Aluminium alloy. The author has an hindex of 5, co-authored 26 publication(s) receiving 57 citation(s).

Efficacy of α-β grade titanium alloy powder (Ti–6Al–2Sn–2Zr–2Mo–2Cr–0.25Si) in surface modification and corrosion mitigation in 3.5% NaCl on friction stir processed armour grade 7075-T651 aluminum alloys—insight in defence applications

Abstract: Aluminium alloy AA7075-T651 is one of the newest and promising commercials rolled sheet metal for structural applications in defensive areas like military, space and air vehicle, aerospace because of its excellent and unbeatable combination of high strength-to-weight ratio and good corrosion resistance, high fatigue strength. In this study friction stir processing (FSP) was performed on AA7075-T651 aluminium metal composite (AMC) reinforced with α-β grade Titanium alloy powder (Ti–6Al–2Sn–2Zr–2Mo–2Cr–0.25Si) which is an excellent reinforcement material in airframe and jet engine applications for corrosion resistance and exceptional strength-to-weight ratio. The processing parameters used were the rotational speed of 1500 rpm, processing speed of 20 mm min−1, and tilt angle of 3°. Two passes were carried out on the FSP parameters with 100% inter-pass overlap i.e. plunge depth of 0.3 mm was used which was distributed thus, 0.2 mm plunge depth on first pass and 0.1 mm plunge depth second pass. Mechanical characterization was carried out to study the influence of α-β grade Titanium alloy powder (Ti–6Al–2Sn–2Zr–2Mo–2Cr–0.25Si), in this tensile strength was studied using Xforce P type of Zwick/Roell Z250 tensile testing machine and surface roughness analysis was conducted on Mitutoyo surf test SJ-210 surface roughness tester. Corrosion behaviour of the processed AMC was studied using potentiodynamic polarization technique in 3.5% NaCl solution at an ambient temperature of 25°. It was established that α-β grade Titanium alloy powder as reinforcement inhibitor produced the highest percentage of inhibition performance efficiency (IPE) of 98.26% while the processed base metal (PBM) gave IPE of 63.99% with reference to the unprocessed base metal (UBM). There was an extraordinary improvement in corrosion rate with a reduction from 5.0718 mm/year to 0.087 675 mm/year when α-β grade Titanium alloy powder was used as inhibitor. AA7075-T651/Ti–6Al–2Sn–2Zr–2Mo–2Cr–0.25Si AMC has highest ultimate tensile strength (UTS) of 624 MPa which has a close value of 620.903 MPa to that of AA7075-T651 without reinforcement but the UTS for UBM was far away from them.

Solid-State Welding: Friction and Friction Stir Welding Processes

Abstract: ,!7ID0D0-dhabef! Order Quantity A. Barkalov, University of Zielona Gora, Poland, Chair of Applied Mathematics and Theory of Control Systems, Vasyl Stus‘ Donetsk National University (in Vinnytsia), Zielona Gora, Ukraine; L. Titarenko, University of Zielona Gora, Kharkov National University of Radio Electronics, Zielona Gora, Poland; K. Mielcarek, Institute of Metrology, Electronics and Computer Science, Zielona Góra, Poland; S. Chmielewski, State Higher Vocational School (PWSZ), Głogów, Poland

Influence of Rapid Solidification on the Thermophysical and Fatigue Properties of Laser Additive Manufactured Ti-6Al-4V Alloy

Abstract: Modern industrial applications require materials with special surface properties such as high hardness, wear and corrosion resistance. The performance of material surface under wear and corrosion environments cannot be fulfilled by the conventional surface modifications and coatings. Therefore, different industrial sectors need an alternative technique for enhanced surface properties. The purpose of this is to change or enhance inherent properties of the materials to create new products or improve on existing ones. The most effective and economical engineering solution to prevent or minimize such surface region of a component is done by fiber lasers. Additive manufacturing (AM) is a breaking edge fabrication technique with the possibility of changing the perception of design and manufacturing as a whole. It is well suitable for the building and repairing applications in the aerospace industry which usually requires high level of accuracy and customization of parts which usually employ materials known to pose difficulties in fabrication such as titanium alloys. The current development focus of AM is to produce complex shaped functional metallic components, including metals, alloys and metal matrix composites (MMCs), to meet demanding requirements from aerospace, defense, and automotive industries.

Tool rotational speed impact on temperature variations, mechanical properties and microstructure of friction stir welding of dissimilar high-strength aluminium alloys

Abstract: Temperature variations during friction stir welding result from the heat generated by the frictional action of a rotating tool on the workpiece. This temperature distribution affects the mechanical behaviour and ultimately the quality of welds produced. The study of the correlations between process parameter, temperature, mechanical properties and microstructure has become imperative in order to promote welds devoid of defects and possessing sound mechanical properties and to establish a temperature feedback control for effective components designs for industrial applications. This work studied the impact of tool rotational speed on temperature profile, mechanical behaviour and microstructure of friction stir welding of dissimilar aluminium alloy 6101-T6 and 7075-T651. Processing parameters of three different rotational speeds with values 1250 rpm, 1550 rpm and 1850 rpm and a constant travel speed of 50 mm/min were employed. The temperature profile was measured with one end of thermocouple wires embedded in the plates and the other end connected to a data capturing software device. The temperature profile indicates that the temperature rises with time and is higher at the retreating sides than at the advancing side of the weld. The tensile test results show that the ultimate tensile strength decreases as the temperature increases. Microstructural observations of weld zone revealed non-uniformity in material flow. However, more material penetration into each other occurred more at 1550 rpm.

The Effects of Rapid Cooling on the Improved Surface Properties of Aluminium Based Coatings by Direct Laser Deposition

Abstract: The deterioration of materials during industrial application poses a serious threat to the materials structural integrity. A material’s susceptibility to wear and surface damage can be reduced by alteration of its surface chemistry, morphology and crystal structure. Therefore, modification of surface properties plays an important role in optimizing a material’s performance for a given application. Modern industrial applications require materials with special surface properties such as high hardness, wear and corrosion resistance, therefore materials engineers are vital to regularly examine how the microstructure of a material can be altered. Aluminium-based alloys have a wide application in the automotive, domestic and aerospace industries due to their excellent mechanical properties such as good weldability, sound castability and outstanding resistance to corrosion. The purpose of this research is to enhance inherent properties of the materials to create new products or improve on existing ones. The most effective engineering solution to prevent or minimize such surface region of a component is done by fibre lasers. It was concluded that Hypereutectic Al-Si alloys having transition metals are exceptional materials due to their specific properties. The addition of Cu, Fe, Cr, Si, Mg and Ni to Al-based alloys can improve the mechanical properties at both ambient and elevated temperatures.

Surface engineering and chemical characterization in ion nitrided titanium and titanium alloys

Abstract: The chemical and physical characteristics of ion-nitrided surface layers, obtained on α-β titanium alloys, are examined and correlated both with the working conditions adopted in the ion-nitriding process and with the alloy chemical composition. Besides the influence of the working parameters on the morphology and on the microstructures of the ion-nitrided surface layers, mainly the alloy element distributions both in surface coatings and in the substrate are analysed for five α-β titanium alloys of industrial use, and for titanium c,p. as reference, ionnitrided at various treatment temperatures. The nitriding process forms, on titanium alloy parts, high-hardness surface layers consisting of TiN (δ phase) and Ti2N (ɛ phase) nitrides and an interstitial solid solution of nitrogen in the close-packed hexagonal lattice of titanium (α phase). The presence and the extent of these phases as well as the ion-nitrided layer morphology are essentially determined by the alloy chemical composition and the working parameters. In particular a low-temperature treatment produces an extended nitrogen diffusion in the matrix beneath a thin continuous nitrided layer, while a high-temperature treatment produces prevalently a continuous nitrided surface layer. The alloy element distribution appears differentiated in the various phases and may be correlated with the different affinity of these elements with nitrogen.

Experimental investigation of laser metal deposited icosahedral Al-Cu-Fe coatings on grade five titanium alloy

Abstract: Laser Additive Manufacturing is relatively new in the manufacturing industry. This paper focuses on the effect of hybrid coatings of Al-Cu-Fe on a grade five titanium alloy (Ti6Al4V) using laser metal deposition (LMD) process at different laser power and scanning speeds. Icosahedral Al-Cu-Fe as quasicrystals are a relatively new class of materials which exhibit unusual atomic structure and useful physical and chemical properties. Ti6Al4V/Al-Cu-Fe composite were analysed using Optical microscopy, Scanning electron microscopy (SEM) with energy dispersive microscopy (EDS), indentation testing, X-Ray Diffraction (XRD), corrosion and wear testing. deposit width and height, heat affected zone (HAZ) height), dilution rate, aspect ratio and powder efficiency of each sample remarkably increased with increasing laser power due to the laser-material interaction. It was observed that there are higher number of aluminium and titanium presented in the formation of the composite. The indentation testing reveals that for both scanning speed of 0.8m/min and 1m/min, the mean hardness value decreases with increasing laser power. It was found that due to dilution effect, a part of Ti entered into molten pool from the substrate. The results indicate that Ti, Al 3 Ti, Ti 3 Al, CuTi 2 can be produced through the in situ metallurgical reactions during the LMD process.

Numerical investigation of laser deposited Al-based coatings on Ti-6Al-4V alloy

Abstract: Titanium Alloy (Ti6Al4V) opened a wide range of useful applications in aerospace industries; these industries make use of different additive manufacturing (AM) techniques to obtain parts of different properties for different uses by this titanium alloy. Ttitanium alloy mainly stands out due to the properties such as high specific strength to weight ratio, and excellent corrosion resistance. Despite these benefits, the formation of defects such as pores and cracks play a vital role in the quality of the deposited coatings. The presence of these unwanted artefacts on laser deposited coatings depends on the melting, cooling and solidification of the melt pool. In this research, a simulation of the heat transfers and fluid dynamics of the melt pool is developed to predict the process parameters and reinforcement proportions on the clad geometry quality. The results were compared to the experimental results for confirmation and validation. Numerical modelling using COMSOL multiphysics 5.2 revealed the thermal behaviour of the coated samples.

Fabrication of bulk aluminum-graphene nanocomposite through friction stir alloying:

Abstract: Friction stir alloying is primarily employed for the fabrication of surface composite to improve surface properties like hardness, wear resistance, and corrosion resistance without significantly af...

Effects of Cooling Rate and Silicon Content on Microstructure and Mechanical Properties of Laser Deposited Ti-6Al-4V Alloy

Abstract: The growth in the use of titanium alloy components in marine industries, aerospace, medical apparatus and power machinery has increased because of its good properties. Some detriments such as low hardness, poor thermal stability and poor tribological properties has however limits its wide range application to the industries. This has led to a search for techniques to improve the surface of Ti-6Al-4V alloy to enhance longevity in service. Laser deposition is one of the feasible techniques to modify the surface of titanium alloy which involves addition of reinforcements to improve properties without changing the bulk properties while optimizing the parameters.Hence, laser surface modification by incorporating chemical barrier coatings can be very beneficial and this lead to investigation aimed at enhancing the surface properties of Ti-6Al-4V alloy by incorporating Al-Si-Ti coatings. For this purpose, a 3-kW continuous wave ytterbium laser system attached to a KUKA robot which controls the movement during the alloying process was utilized to deposit coatings with stoichiometry Al-12Si-3Ti and Al-17Si-5Ti. The alloyed surfaces were investigated in terms of its mechanical properties as function of the laser processing conditions. Hardness measurements were done using a Vickers micro-hardness tester. The microstructures of the coated and uncoated samples were characterized by optical and scanning electron microscopy. The optimum performances were obtained for an alloy composition of Al-17Si-5Ti, at laser power of 900 W and coating speed of 1.2 m/min. Its performance enhancement compared to the unprotected substrate comprised a significant increase in hardness from 296 to 689 HV which translates to 57.04% in hardness values above that of the substrate.The enhanced increase in hardness of the coating can be traced to the presence of silicon and the various hard titanium aluminides intermetallic (TiAl, TiAl3, and Ti3Al) phasese.