The Gallatin plant, located in northern Kentucky, produces flat rolled steel and has an annual capacity of 1.8 million tons.
ArcelorMittal, the world’s largest steelmaker, said it expected the all-cash deal to close by the end of the year.
Nucor, which already operates four flat-rolled mills, said the purchase would increase its annual flat-rolled capacity by 16 percent to about 13 million tons and help it better serve customers in the pipe and tube segment.
That business has been growing in the United States thanks to demand from the oil and natural gas sector, where the pipes and tubes are used in hydraulic fracking.
Reporting by Robert-Jan Bartunek in Brussels and James B. Kelleher in Chicago; editing by Philip Blenkinsop and Cynthia Osterman