Browsing by Author "Olorunniwo, O. E."

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The contribution of eutectic liquid film to the TMAZ microfissuring in intertia friction welded PM RR1000 superalloy
(The Nigerian Institution of Mechanical Engineers, 2010) Oluwasegun, K. M.; Olorunniwo, O. E.; Oluwole, O. O.
The microstructure of the base alloy and thermomechanical affected zone (TMAZ) of inertia friction welded powder metallurgy (PM) RR1000 were examined by the use of standard metallogrphic techniques involving optical, analytical scanning transmission electron microscopes equipped with energy dispersive spectometer and an electron probe micro analyser. It was discovered that liquation of grain boundary phases present in the pre-weld alloy resulted in the formation of eutectic type ƴ-ƴ1 solute rich liquid film predominant in the TMAZ regions whic contributed significantly to micro fissuring during welding. It was found that apart from the effect of rapid precipitation of ƴ particles on the TMAZ cracking as has been widely reported, constitutinal liquidation of ƴ particles was a notable part of liquidation process which promoted the susceptibility of TMAZ to microcracking.
Earing characteristics of cold-rolled and temper annealed aluminium 1200
(Asian Network for Scientific Information, 2006) Aderibigbe, D. A.; Oluwole, O. O.; Olorunniwo, O. E.; Atanda, P. O.; Ogundare, O.
Earing characteristics of deep-drawn cold-rooled and temper-annealed 1200 was studied at high deformation levels of 75,85,and 90% cold rolling. The relationshp of earing with varying degrees of cold roll was studied and the effect of different annealing temperatures on earing. Hardness, ductility and strength variations with earing were also studied. Earing was at an aneeal-temperature. The relationship of earing to hardness, ductibility and strength properties were observed to follow the same pattern. Hardness, ductility and strength properties of cold-rolled and temper-annealed Aluminium 1200 at lowest eaaring did not necessarily correspond to the materials lowest hardness, highest ductility or lowest strength respectively and were found to vary for varying degrees of cold-roll.
Effect of iso-thermal treatment on the corrosion behaviour of low carbon steel (Nigerian C2R grade) in a buffered solution containing chloride and carbonate ions
(2012) Atanda, P. O.; Olorunniwo, O. E.; Alabi, O. D.; Oluwole, O. O.
This work has investigated the corrosion behavior of low carbon steel subjected to four different modes of iso-thermal heat treatment and then immersed in a neutral buffer corrosive medium containing carbonate and chloride ions. The low carbon steel material was cut into twenty small pieces of length 18±2mm, put in groups of five and subjected to: Annealing, Hardening, Normalizing and tempering, each corresponding to an iso-thermal mode of treatment. The samples were ground and polished, and micrographs taken for each mode of treatment. The samples were then immersed into the corrosion medium; a neutral buffer and samples were withdrawn for measurement every 72 hours. The experiment lasted 360 hours (15 days). The weight loss due to corrosion of the samples, the corrosion rate of the samples and the pH variation of the samples were monitored against time of exposure. It was observed that samples which had undergone tempering mode of heat treatment turned out to be the ones with the best corrosion resistance.
Effect of magnesium and calcium as spheroidizer on the graphite morphology in ductile cast iron
(2007) Oluwole, O. O.; Olorunniwo, O. E.; Ogundare, O. O.; Atanda, P.O.; Oridota, O. O.
This study investigated the effect of magnesium and calcium as spheroidizers on the graphite microstructure in cast iron. The cast iron samples were melted in an induction furnace with charge of known composition and, magnesium and calcium of known percentages were added as spheriodizers to the molten metal in the mould during the casting process. From the microstructure of the as- cast specimens it was observed that the use of 100% Mg and a combined addition of 60% and 40%Ca as spheriodizers produced graphite spheroids instead of graphite flakes in the cast iron microstructure. The use of 100% Ca addition resulted in the production of graphite flakes in the specimen microstructure. The use of 80% Mg and 20% Ca resulted in the production of a chunky, stubby graphite microstructure, while the additions of 50% Mg and 50% Ca, 40%Mg and 60% Ca, and 20% Mg and 80% Ca resulted in the microstructure having a flaky graphite microstructure.
Simulation of riser size from musty zone of unrisered Alsi7mg alloy
(INSInet Publication, 2007) Oluwole, O. O.; Olorunniwo, O. E.; Atanda, P. O.
Solidification simulation packages incorporate risers in their Finite Element meshing programs. The placement of the risers is normally juggled in different positions until the best positions are obtained. Also riser sizes are also determined based on riser size calculations. This work has narrowed down position options by first simulating unrisered castings of an AlSi7Mg alloy. Using the location of the mushy zone and the size of the zone, appropriate size and locations were determined for the riser thus limiting the number of trial and error simulation runs. Using the size and locations of mushy zone it has been discovered that risers of equivalent lineal size should be placed in the locations of these mushy-zones. Simulations were done using a rectangular block and a gas burner.
Simulation studies of nodular iron's bull's eye effect on stress concentration under plane stress conditions
(2007) Oluwole, O. O.; Olorunniwo, O. E.
A simulation study on the effect of the "bull's eye" in ductile iron on stress concerntrations was done in this work. Using the model of graphite nodules in a cavity, a two dimensional plate strip was subjected to plane stress conditions. The results were compared to to the traditonal theory of modeling the graphite in the hole model showed the hole matrix. In plane stress condition, while the graphite in the hole model showed the hole as areas of stress concerntration and therefore very critical as regards fracture, the hole model showed stress concentrated away from the holes making the holes not very critical factor as regards fracture. It was observed that areas of stress application were more critical than voids when using the hole model. Also the graphite in the hole model was able to predict the good damping behaviour of ductile iron and the increasing elongation with decreasing nodule count.
Strengthening of Alloy steel by high temperature thermomechanical treatment
(INSInet Publication., 2006) Omotyinbo, J. A.; Olorunniwo, O. E.; Ogundare, O.; Oluwole, O. O.
Micro-alloyed steels produced by controlled rolling are of the most attractive propositions in many engineering applications because of their relative low cost, moderate strength and very good toughness when compared with as-castalloy steel.. This research work has shownthe possible substitution of cheaper, low-alloy steel for the high alloy steel for the same application. The effect ofHTMT onthe mechanical properties of low alloy steel was investigated.