Reinforcing bar, which it is commonly abbreviated as rebar, is used in theudconstruction industry to impart tensile strength to concrete structures, whichudby nature is very brittle. At ArcelorMittal South Africa Newcastle Works, 460udMPa (minimum yield strength) rebar is traditionally produced by usingudVanadium as a micro-alloying addition in order for the mild steel to attain theudrequired strength as specified. However, the fluctuating price of Vanadiumudover the past years necessitated the use of alternative micro-alloyingudelements. Niobium is currently used successfully instead of Vanadium on theudRod mill, but not on the Bar mill, due to the difference in cooling facilitiesudbetween these rolling mills.udAlternative manufacturing routes and strengthening mechanisms for the costudeffective production of rebar containing Niobium on the Bar mill wasudinvestigated. It was decided to produce a trial cast containing Niobium as audmicro-alloying element with a Chromium addition and subsequently roll it intoud10 mm and 12 mm rebar at the Bar mill. The minimum yield strength of 460udMPa was not achieved. The average yield strength was approximately 430udMPa on both these sizes.
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