BlueScope bought IMSA from Latin American steelmaker Ternium SA. It will also take on $20 million in under-funded pension liabilities.
"This acquisition greatly accelerates BlueScope Steel's North American strategy allowing us to significantly broaden our scope and geographic reach," BlueScope Chief Executive Paul O'Malley said in a statement on Thursday.
He said BlueScope knew IMSA's four business operations well. In fact, BHP Billiton, from which BlueScope was spun off in 2002, used to own two of the businesses that BlueScope is now buying from IMSA. BHP had sold them to IMSA in 2000.
BlueScope said the acquisition, to be completed in early 2008, will lift earnings per share from the 2009 fiscal year. It expects to make about $40 million per year in cost savings within three years.
Ternium, which is controlled by Argentina's TechInt conglomerate, has steel operations in Mexico, Venezuela and Argentina.