Dofasco Inc., Hamilton, Ontario, Canada, produces flat-rolled steels mainly for the automotive industry. In 1983, Dofasco brought a new hot-rolling mill on line to roll high-strength, low-alloy steels. "If it isn't done right, HSLA can produce a lot of weird mi-crostructures," warns John Worobec, senior research engineer-thermal/mechanical simulation. Dofasco bought the Gleeble 1500, a simulation and testing machine from Dynamic Systems Inc., Poestenkill, NY, to predict how the new set-up would work. "One of the reasons we bought a Gleeble 1500 was to determine the hot-rolling characteristics of our steels," says Worobec. "The essential question was: 'How do our bread and butter products transform during the hot-rolling process?'" In buying the Gleeble 1500, Dofasco received a machine designed to optimize process performance. "Most of our initial work with the Gleeble was to develop continuous cooling transformation (CCT) diagrams for 11 typical grades of steel," says Worobec. "We were able to tell the hot-rolling people where their finishing and coiling temperatures should be in order to produce uniform mechanical properties, particularly for automotive applications. We were also able to tell them they need very low cooling rates to avoid intermediate structures. We still produce CCTs for any new material we make.
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