In a move that buyer sources say—and some flat out hope—is a harbinger of things to come, AK Steel Corp. plans to increase prices on carbon flat-rolled sheet products by $20 to $30 per ton starting with January shipments.

Several buyer sources said they have been told in private discussions that U.S. Steel Corp., Pittsburgh, also will boost spot market prices on carbon flat-rolled products by similar amounts.

West Chester, Ohio-based AK Steel's announcement calls for hot-rolled sheet prices to increase by $20 per ton, with cold-rolled and coated sheet products rising $30 per ton.

Spot market hot-rolled sheet is around $500 per ton ($25 per hundredweight) currently, down from a range of $560 to $580 per ton ($28 to $29 per cwt) last month, while cold-rolled sheet is about $620 per ton ($31 per cwt) and hot-dip galvanized sheet is around $750 per ton ($37.50 per cwt).

Sources hesitated to call the AK increase a market-leading move, with some saying that AK's prices lag some of its competitors by...