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Search Results: 1 - 10 of 190435 matches for " O. I. Sekunowo "
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Effect of Deformation on the Mechanical and Electrical Properties of Aluminum-Magnesium Alloy  [PDF]
S. O. Adeosun, O. I. Sekunowo, S.A. Balogun, L.O. Osoba
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.106042
Abstract: This paper presents the effect of deformation on the tensile strength, toughness, hardness and electrical resistance of aluminum 6063 alloy. Cast samples were cold rolled in the range of 0-24 percent thickness reduction and subjected to mechanical (static, dynamic) and electrical resistance tests. Results show significant improvement in hardness and electrical resistance properties of the alloy. The nature, amount and distribution of the secondary phase, Mg2Si,particles precipitated within the matrix which was influenced by the extent of cold-work, are responsible for the observed behaviour. The resistance of the alloy also depends on the degree of cold work carried out prior to use.
Effects of Heat Treatment on Strength and Ductility of Rolled and Forged Aluminum 6063 Alloy  [PDF]
S. O. Adeosun, S.A. Balogun, O.I. Sekunowo, M.A. Usman
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.98054
Abstract: This work examines the effect of heat treatment on tensile strength and ductile responses of rolled and forged AA6063 aluminum alloy. Some cast samples were rolled while some were forged at ambient temperature (32℃). The deformed samples were subjected to heat treatment processes. The tensile strengths of rolled (212 MPa) and forged (127 MPa) samples are enhanced at ambient temperature but with poor elongation responses. A combination of improved strength and elongation (127 MPa, 24%) can be obtained in rolled sample when solution heat treatment (SHT) is applied after deformation and cooling in water. The forged sample when homogenized, solution treated and water quenched has elongation of about 24% with improved strength of 137 MPa. These results were obtained because of the development of very fine AlFeSi texture in the matrix and along the grain boundaries.
Mechanical Response of Al-1.09Mg2Si Alloy under Varying Mould and Thermal Ageing Conditions
O. I. Sekunowo,G. I. Lawal,S. O. Adeosun
Journal of Metallurgy , 2012, DOI: 10.1155/2012/921235
Abstract:
Mechanical Response of Al-1.09Mg2Si Alloy under Varying Mould and Thermal Ageing Conditions
O. I. Sekunowo,G. I. Lawal,S. O. Adeosun
Journal of Metallurgy , 2012, DOI: 10.1155/2012/921235
Abstract: Samples of the 6063 (Al-1.09Mg2Si) alloy ingot were melted in a crucible furnace and cast in metal and sand moulds, respectively. Standard tensile, hardness, and microstructural test specimens were prepared from cast samples, solution treated at 520°C, soaked for 6?hrs, and immediately quenched at ambient temperature in a trough containing water to assume a supersaturated structure. The quenched specimens were then thermally aged at 175°C for 3–7?hrs. Results show that at different ageing time, varied fractions of precipitates and intermetallics evolved in the specimens’ matrices which affect the resulting mechanical properties. The metal mould specimens aged for four hours (MTA-4) exhibited superior ultimate tensile strength of 247.8?MPa; microhardness, 68.5?HV; elongation, 28.2% . It is concluded that the extent of improvement in mechanical properties depends on the fractions, coherence, and distribution of precipitates along with the type of intermetallics developed in the alloy during ageing process. 1. Introduction Casting is one of the most versatile methods of producing structural aluminium alloy components. However, the rather large preponderance of defects in cast aluminium components often limits their performance and adversely impacts their commercial values. Hence there is the need for a novel processing approach to improve the cast microstructure for enhanced performance. Generally, the poor mechanical properties of cast aluminium alloys can be improved through either alloy addition or various forms of heat treatment [1]. During the heat treatment of cast aluminium alloys, an advantage is made of the characteristic decrease in solubility at low temperature of magnesium (Mg) and silicon (Si) which are the main alloying elements in Al-Mg-Si alloy. Further, Keist [2] confirms that the appreciable decrease in concentration of the alloying elements at room temperature is the fundamental phenomenon that provides the basis for increasing substantially the hardness and strength of aluminium alloys through isothermal treatment. Similarly, Siddiqui et al. [3] have shown that improved ductility can be achieved by process annealing at 415°C, soaked between two and three hours coupled with a cooling rate 30°C per hour. Generally, strength improvement of most 6063 aluminium alloys can be effected in a three-pronged approach comprising solution heat treatment, quenching, and precipitation of solute atoms [4]. However, the greatest challenge usually encountered with this approach is effective control of the second-phase precipitates. Lumley et al. [5]
Mechanical Characteristics of 6063 Aluminum-Steel Dust Composite
S. O. Adeosun,E. I. Akpan,O. I. Sekunowo,W. A. Ayoola
ISRN Mechanical Engineering , 2012, DOI: 10.5402/2012/461853
Abstract:
Corrosion Behaviour of Heat-Treated Aluminum-Magnesium Alloy in Chloride and EXCO Environments
S. O. Adeosun,O. I. Sekunowo,S. A. Balogun,V. D. Obiekea
International Journal of Corrosion , 2012, DOI: 10.1155/2012/927380
Abstract: Machines designed to operate in marine environment are generally vulnerable to failure by corrosion. It is therefore imperative that the corrosion susceptibility of such facilities is evaluated with a view to establishing mechanism for its mitigation. In this study, the corrosion behaviour of as-cast and retrogression-reagion (RRA) specimens of aluminum alloy containing 0.4–2.0 percent magnesium additions in NaCl, FeCl3, and EXCO solutions was investigated. The corrosion simulation processes involved gravimetric and electrochemical techniques. Results show substantial inducement of Mg2Si precipitates at a relatively higher magnesium addition, 1.2–2.0 percent, giving rise to increased attack. This phenomenon is predicated on the nature of the Mg2Si crystals being anodic relative to the alloy matrix which easily dissolved under attack by chemical constituents. Formation of Mg2Si intermetallic without corresponding appropriate oxides like SiO2 and MgO, which protect the precipitates from galvanic coupling with the matrix, accentuates susceptibility to corrosion. 1. Introduction Aluminum and its alloys are widely used in industry because of their light weight, high strength, and good corrosion resistance which is due to the formation of a protective oxide layer. However, under saline conditions such as those encountered in marine environments, aluminum alloys are vulnerable to localised degradation in forms of pitting and crevice corrosion. This type of corrosion involves the adsorption of an anion in particular chloride ion, Cl-, at the oxide-solution interface. In conventional metallic materials, the strong oxidizing power of the environment is required to establish spontaneous passivity; hence, to be of practical use, metallic materials must exhibit significant level of passivity in a given environment. The passive stable surface film acts as a barrier for the transfer of cations from the metal to the environment and for the counter diffusion of oxygen and other anions. The air-formed film must be stable without damage to the underlying alloy surface in a given environment. Chemically homogenous, single-phase amorphous alloys free from crystalline defects such as precipitates, segregates, grain boundaries, and dislocations often create conducive environment for the formation of uniform passive film without any weak points [1]. Aluminum forms a protective oxide film in the pH range 4.0–8.5, but this depends on temperature, form of oxide present, and the presence of substances that form soluble complexes or insoluble salts with aluminum. This implies that
Effect of Artificial Aging on Plane Anisotropy of 6063 Aluminium Alloy
S. O. Adeosun,O. I. Sekunowo,M. A. Bodude,A. A. Agbeleye
ISRN Metallurgy , 2012, DOI: 10.5402/2012/639319
Abstract:
Evaluation of the Mechanical Properties of Polypropylene-Aluminum-Dross Composite
S. O. Adeosun,M. A. Usman,W. A. Ayoola,I. O. Sekunowo
ISRN Polymer Science , 2012, DOI: 10.5402/2012/282515
Abstract:
Evaluation of the Mechanical Properties of Polypropylene-Aluminum-Dross Composite
S. O. Adeosun,M. A. Usman,W. A. Ayoola,I. O. Sekunowo
ISRN Polymer Science , 2012, DOI: 10.5402/2012/282515
Abstract: Aluminum (Al) dross is a hazardous waste from the secondary smelting of aluminium industries, and safe disposal of this waste is a big challenge to these industries. Dumping of this waste is an environmental hazard to plants, animals, and even human beings. This study is aimed at improving the mechanical properties of polypropylene (PP) by adding Al dross in 2–50?wt% for particle sizes 53?μm and 150?μm. PP-Al-dross composite samples were cast, and ultimate tensile strength (UTS), impact resistance (IR), water absorption (WA), and density (D) tests were carried out. The results obtained show that UTS improved by 68% (at 15?wt% Al-dross addition), D increased by 54% (at 50?wt% Al-dross addition), and WA by 500% (at 8?wt% Al-dross addition) over the convectional PP. The impact resistance of the composite was found to be the same (68?J) with that of conventional PP at 15?wt% Al dross. 1. Introduction Aluminum (Al) drosses (white and black) are residues from primary and secondary aluminum production formed on the surface of molten Al that is exposed to furnace atmosphere during fusion processing. The dross is usually a mixture of free Al metal and nonmetallic substances such as aluminium oxide, nitride, and carbide; salts; metal oxides [1]. Disposal and recycling of dross is a worldwide problem. Majority of dross is disposed of in landfill sites, which is likely to result in leaking of toxic metal ions into the ground water causing serious pollution problems. In addition to this, when aluminium dross comes in contact with water it emits harmful gases such as NH3, CH4, PH3, H2, and H2S [2]. When the dross particles are allowed to escape into the atmosphere, inhalation can cause health problems such as Alzheimer’s disease, silicosis, and bronchitis. The challenge posed by aluminium dross to the environment has continued to engage the attention of researchers over the years. Efforts are geared towards putting this otherwise hazardous waste to productive use. For example, it has been used as reinforcement for aluminium-matrix [3], as raw material for refractories [4], and as additive in cement production [5]. It has also been used in the synthesis of adsorbent and catalytic materials such as alumina and zeolites [6–13]. Polypropylene (PP) is a commodity polymer that has found wide range of applications in the packaging, textile, automobile, and furniture industries because of its good processbility, recyclability and low cost [14–16]. It has limited use as engineering thermoplastic due to its low strength, low modulus, and high notch sensitivity. To address this
Effect of Artificial Aging on Plane Anisotropy of 6063 Aluminium Alloy
S. O. Adeosun,O. I. Sekunowo,M. A. Bodude,A. A. Agbeleye,S. A. Balogun,H. O. Onovo
ISRN Metallurgy , 2012, DOI: 10.5402/2012/639319
Abstract: Most aluminum profiles’ production by deep-drawing and extrusion processes require certain degree of structural homogeneity because of the segregated second-phase particles in the as-cast structure. Rolled texture and directionality in properties often give rise to excessive earring, breakout, and tears. This study investigates the effect of heat treatment (artificial aging) on the anisotropic behavior of AA6063 alloy between rolling direction (0°) through 90° directions. The results show significant reduction in property variability in the aged samples along the rolling direction 0°, and 90° directions compared with the as-cast samples. This gave rise to improved % elongation, impact toughness, and substantial reduction (33.3%) in hardness. These results are capable of achieving huge savings in die conditioning and replacement with improved quality and sale of deep-drawn AA6063 alloy profiles for sustained profitability. 1. Introduction In metal forming, texture gradients often ensued due to nonhomogeneous flow. Texture heterogeneities can also occur in other deformation modes, such as sheet rolling, wire drawing and tube extrusion. Thus, in many industrial forming processes for aluminum, mechanical loading is usually combined with some form of heat treatment such as annealing between deformation steps. This serves the purpose of mitigating substantially strain-hardening phenomenon during deformation. A particular example is the stretching of aluminum parts in a number of stages with intermediate annealing treatments. However, this heating and cooling cycle often results in time wastage and could be minimized. The cause of work hardening during mechanical working varies in different aluminium alloy compositions. Hardening of nonheat treatable Al-Mg alloys is due mainly to the presence of solute atoms in solid solution. In heat treatable Al-Mg-Si and Al-Cu alloys, strengthening is determined by precipitates formed during aging treatment. For room-temperature forming, the material behaviour of aluminum sheet is completely determined by work hardening and almost independent of the strain rate [1]. Previous study showed that profiles extruded from both homogenized and unhomogenized billets did exhibit the same mechanical properties and metallurgical features [2]. Hence, the whole homogenizing process could be eliminated without compromising any of the mechanical properties. It is established that the factors that determine behaviour of aluminium alloy component are the type, amount, and distribution of second-phase particles such as Al-Fe, Al- Fe-Si, and
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