Nucor Corp. will invest $85 million to upgrade the rolling mill at its steel bar mill in Marion, Ohio. Nucor Steel Marion Inc., Ohio's largest producer of rebar and signpost, is capable of producing over 400,000 tons annually. The modernization project has the potential to add 15 jobs at the mill, which recently celebrated its 100th year of steelmaking. Updating the technology used in the rolling mill will help Nucor Steel Marion maintain a cost-competitive position by reducing operating costs.