Browsing by Author "Senfuka, C."

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    The Concrete Reinforcing Value of Recycled Steel Bars in Uganda
    (IOSR Journal of Engineering, 2013) Senfuka, C.; Kirabira, J.B; Byauhanga, J.K.
    The energy absorbing capacity of the reinforcement bars in concrete only occurs after the yield point. If the yield point of steel is too high, stresses in the concrete reach failure level before the yield point of the steel, allowing the formation of large shear and bond stresses at time of yield and ultimate brittle collapse. High yield is equally associated with reduced yield platform and energy absorption. Steel reinforcement bars in Uganda, mainly cold twisted, are often of high yield even though they amply meet the standard ductility requirements. This has largely been attributed to their recycled origin. This research investigates the relationship between the elevated yield values and the residual element content which in turn is a direct result of steel recycling.
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    Weldability of Recycled Steel Bars in Uganda
    (International Journal of Engineering and Technology, 2012) Senfuka, C.; Kirabira, J.B.; Byauhanga, J.K.
    The metallurgical reliability of welded recycled steel made in Uganda has been studied through the examination of manual metal arc weldments of steel samples of 0.27%C and less using the dye penetrant flaw detection method, micro-hardness plots and spark spectromentry. This method was selected to ensure reproducibility by taking repeated readings on the same sample since it is largely non-destructive. About thirteen percent of the samples exhibited post-weld cracks. Of these, 3% of the samples yielded hot cracks while the other 10% showed typical hydrogen assisted cracks. The cracking sensitivity has been attributed to the presence of large numbers and quantities of residual elements rather than high carbon content in particular. This resulted from the predominantly recycled production mode in the country. The use of more elaborate refining methods and the exploitation of virgin iron resources have been recommended. Pre- and post-heating techniques have been advised whenever weld cracking threatens.