U.S. steelmakers projected lower quarterly profits, as automotive companies and equipment manufacturers dial down production.

Charlotte, N.C.-based Nucor said Tuesday that lower demand for steel in a weakening manufacturing sector and falling sales of its steel construction materials would result in about an 80% decline in third-quarter profit, including one-time charges, from the same quarter last year. Indiana-based Steel Dynamics late Monday forecast lower quarterly profit as well, describing earnings from its steel business as being "meaningfully lower" from the prior quarter because of weak demand and lower steel prices.