NEW YORK – The U.S. shale gas revolution, which has revitalized chemical companies and prompted talk of domestic energy self-sufficiency, is attracting a wave of investment that may revive profits in the steel industry.

Austrian steelmaker Voestalpine said last month that it may build a $661 million factory in the United States to benefit from cheap gas. Nucor Corp., the most valuable U.S. steelmaker, plans to start up a $750 million Louisiana project in mid-2013. They’re among at least five U.S. plants under consideration or being built that would use gas instead of coal to purify iron ore, the main ingredient in steel.

“That technology has been around 30 years, but for 29 years, gas prices in the U.S. were so high that the technology was not economical,” said Michelle Applebaum, managing partner at consulting firm Steel Market Intelligence in Chicago. “This is how steel will be built moving forward.”

The new capacity may signal a turnaround for an industry that has suffered from overcapacity since the financial crisis and collapse in commodity prices four years ago. U.S. steelmakers have struggled to stay profitable amid sluggish domestic demand, depressed prices and competition from Chinese imports. While global steel output has grown by 14 percent since 2008, U.S. production has shrunk by 3.4 percent.

The newest group of steel projects are so-called direct-reduced iron plants, or DRIs, which account for the first stage of steelmaking. DRI technology produces iron for about $324 a ton, Nucor said in a November presentation. That’s $82 a ton, or 20 percent, cheaper than using a conventional blast furnace.

Foreign competitors are now following Nucor’s lead. A joint venture between Australia’s Bluescope Steel and commodity trader Cargill plans to build a DRI plant in Ohio, Biliana Pehlivanova and Shiyang Wang, analysts at Barclays in New York, said in a report. India’s Essar Global Ltd. plans one for Minnesota, Barclays said.

Nucor may announce a second DRI plant as soon as 2013, bringing the company’s domestic iron-making capacity to 5 million tons per year, according to Aldo Mazzaferro, a steel analyst at Macquarie Capital USA in New York. Nucor agreed last month to pay Canadian energy corporation Encana $3 billion over two decades for a joint venture that will develop gas wells to supply its DRI capacity.

Hydraulic fracturing, or “fracking,” of shale rock formations from Texas to West Virginia has boosted supplies of gas and sent prices plunging by as much as half in the last two years. Gas futures reached a decade low of $1.91 per million British thermal units in April.

“The shale revolution is triggering an avalanche of industrial expansion plans,” Barclays’ Pehlivanova and Wang said.

There has been a reversal of fortune for U.S. chemical producers after years of decline. Shares of LyondellBasell Industries have more than doubled since it emerged from bankruptcy in 2010. The company is now among chemical producers planning billions of dollars of plants around the Gulf of Mexico to capitalize on cheaper gas. Fertilizer companies also are planning to construct gas-fueled plants.

“Other companies from around the world that consume gas may be attracted to move their facilities to the U.S. market, which would then provide even more steel consumption and manufacturing capacity,” said Macquarie's Mazzaferro. “It could result in a reindustrialization of the U.S.”

Still, gas may not get much cheaper from here. Prices are up by 82 percent from their April low and are expected to average $3.70 per million British thermal units next year, or about 31 percent more than in 2012.

That price trend may continue if the United States starts exports. A study released last month by NERA Economic Consulting found that the country would benefit more from shipping liquefied natural gas than using it all domestically. Sempra Energy and ExxonMobil are among energy companies seeking export permits.

At the same time, there’s no guarantee that steel demand in the United States will improve. Domestic steel industry capacity utilization is at 74 percent, according to data from the American Iron and Steel Institute. Utilization was 91 percent in August 2008, the month before the bankruptcy of Lehman Brothers Holdings.