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Show FUTURE CHANGES IN THE STEEL REHEAT MARKET Natural gas is the market leader of steel reheat fuels, accounting for approximately 135 x 1012 Btu per year of a 186.5 x 1 012Bt u per year potent ia 1 market as shown in Table 3. However, this natural gas market is likely to decline substantially in the future due to technological and structural changes in the steel industry. The entire domestic steel industry, and thus the steel reheat market, will be downsized over the next several years because of the permanent closing of uneconomical mills, the movement to overseas sourcing, and the replacement of old, inefficient equipment with new, more efficient technologies. In addition, over the next 20 years, technological changes in the steel industry such as hot charging, direct rolling, and thin steel casting will move the industry toward more continuous processes that eliminate or reduce traditional reheat steps (see Figure 1). Continuous casting is already used in a large portion of the U.S. steel industry, and its market is growing annually. Such growth creates the opportunity for increased hot charging, which reduces, but does not eliminate, the amount of reheat required. Today, steel is normally hot charged at temperatures from 1,000°F to 1,800°F. Over time, better material handling techniques and improved logistics will allow hot charging at temperatures around 2,000°F. Direct rolling without some form of reheat is unlikely to be widely used in the near term, however. One reason is logistics problems throughout the U.S. steel industry, and a second reason is the need to reheat the cooler edges and corners of the steel product to equalize temperature across the workpiece. An increase in hot charging may lead not only to reduced steel reheat energy consumption, but to the requirement for new reheat technologies. Instead of raising slab temperatures by over 2,OOO°F through several hours' res idence in a reheat furnace, there wi 11 be a movement toward quick reheat, particularly for slab corners and edges. Thin slab casting exists today in a rather crude form. Technological developments for improving product quality will make it commercially available in the next 3-7 years. Today, thin slab •••• Continuous Casting 1I ••• Hot Charging ••• Direct Rolling ••• Thin Slab Casting products still require some reheat for rolling to ensure adequate surface quality, but the amount of rolling required is much lower than that for a cast or continuous cast billet product. Thin slab casting quality may improve to the point where little or no reheat and hot rolling are required, possibly in the next 7-15 years according to the industry representatives interviewed during this study. However, some reduction by hot working may always be required to break down the cast grain structure. Thin strip casting of quality products is at a much lower development stage. Most industry representatives believe that significant use of thin strip casting will not occur for 7-25 years. Before this process is feasible, many product quality problems must be solved. The use of powdered metal technology to directly compact metal powders into finished steel products is questionable. Major technological advances will be required before a wide strip of uniform thickness and quality can be produced. Advances will also be required for the production of low-cost iron powders. The most likely applications of powder metallurgy would be in specialty steel areas, where powdered metals may allow the production of steel grades that are impractical with current melting technologies. The potential impacts of these technologies on the natural gas reheat market are estimated in Table 4 based on 1984 production figures. The hot charging process, if extended to include 25 percent of all continuously cast steel at 1984 levels, would decrease natural gas consumption an estimated 3.7 x 1012 Btu annually. Direct rolling and thin steel casting technologies (i.e., thin strip, thin slab) all seek to eliminate the basic reheat process with the exception of some minor reheating of cooler slab edges and corners to equalize overall temperatures. These technologies pose the most significant potential reductions in natural gas consumption. Based on 1984 production figures, direct rolling could reduce natural gas consumption in ingot casting processes to 67 x 1012 Btu -- half of the estimated natural gas consumption in ingot casting for 1984. Thin strip and thin slab casting could _ Thin Strip Casting 1985 1990 1995 2000 Time ••• 1( Powder Metal Steelmaking 2005 + Fig. 1 - Potential Technological Developments in the U.S. Steel Industry: Timeline for Commercial Availability 298 |