Steels open-hearth

Martin-. (Zron) Martin, open-hearth, -fluss-eisen, n. open-hearth iron, -fluss-stahl, m. open-hearth steel, -ofen, m. Martin furnace, open-hearth furnace, -ofenschlacke,/. open-hearth slag, -roheisen, n. open-hearth pig (iron). -Stahl, m. Martin steel (open-hearth steel). -stahlofeQ, m. open-hearth steel furnace. -verfahren, n. (Siemens-)Martin process, open-hearth process. 

SM-Stahl, m. Siemens-Martin steel, open-hearth steel. 

Fig. 5.23. Refractory checkerwork regenerator, widely used with steel open-hearth furnaces, and still used with large glass-tank melting furnaces. Positions of the bottom valves and fuel lance valves are reversed about every 20 min.

Dead-burned dolomite is a specially sintered or double-burned form of dolomitic quicklime which is further stabilized by the addition of iron oxides. Historically, it was used as a refractory for lining steel furnaces, particularly open hearths, but as of this writing is used primarily in making dolomite refractory brick (see Refractories). 

PefractoTy lime is synonymous with dead-burned dolomite, an unreactive dolomitic quicklime, stabilized with iron oxides, that is used primarily for lining refractories of steel furnaces, particularly open hearths. 

During the years 1981 to 1986, the average consumption of manganese units (as ferroalloys) for the EEC, the United States, and Japan combined, decreased from 6.5 to 5.5 kg/t of steel. Eor the same period in the United States, the consumption of manganese decreased from 6.2 to 4.7 kg/t of steel (33), and apparendy decreased further in the years of 1990, 1991, and 1992 to 4.15, 4.11, 3.85 kg/t of steef respectively (9). In contrast, in 1984, the steel industry of the former USSR, where 50% of steel production was stiU made in open-hearth furnaces, had an average consumption of manganese units of 13 kg/t steel (35). 

A comprehensive history of ferrous scrap recycling ia the United States beginning ia 1646 has beea pubUshed (3). Some selected eveats of iaterest iaclude the first opea-hearth steel produced (1868) the first commercial direct-arc electric furnace steel produced ia the United States (1906) the first large iaduction furnace iastaHed ia the United States (1914) the first basic oxygen steel produced ia the United States (1954) the rise of continuous casters and scrap-based minimills (1965) the first thin-slab continuous caster at a minimill (1989) U.S. exports and imports of ferrous scrap at record highs (1990) and the end of production of open-hearth steel (1991). 

Kingdom. Adapted to steelmaking, the open-hearth process was the principal method for producing steel throughout the world until 1970. As of this writing (1996), it is stiU used in China and the CIS. 

Electric-Arc Furnace. The electric-arc furnace is by far the most popular electric steelmaking furnace. The carbon arc was discovered by Sir Humphry Davy in 1800, but it had no practical appHcation in steelmaking until Sir William Siemens of open-hearth fame constmcted, operated, and patented furnaces operating on both direct- and indirect-arc principles in 1878. At that early date, the avadabiHty of electric power was limited and very expensive. Furthermore, carbon electrodes of the quaHty to carry sufficient current for steel melting had not been developed (see Furnaces, electric). 

In modem steel (qv) manufacture, pebble quicklime is used as a flux in the basic oxygen, basic open-hearth, basic Bessemer, and basic electric furnaces. 

Sihca bricks are used extensively in coke ovens, the roofs and walls of open-hearth furnaces, and the roofs and sidewalls of glass tanks and as linings of acid electric steel furnaces. Although sihca brick is readily spalled (cracked by a temperature change) below red heat, it is very stable if the temperature is kept above this range and for this reason... 

Steel Basic oxygen furnace Open hearth Electric furnace Ore roasters Cupola Pyrites roaster Taconite roaster Hot scarfing... 

Wire used in the manufacture of wire rope is made from (1) acid or basic open-hearth steel, (2) basic oxygen steel, or (3) electric furnace steel. Wire tested before and after fabrication shall meet different tensile and torsional requirements as specified in Tables 4-9 and 4-10. 

The impure iron is made into steel by burning out most of the carbon, sulfur, and phosphorus. Today there are three common furnace types for making steel—the open-hearth furnace (85% of U.S. production), the electric arc furnace (10%), and the Bessemer converter (5%). These furnaces differ in construction but the chemistry is basically similar. 

The process of burning out the impurities is slowest in the open-hearth furnace. This implies there is plenty of time to analyze the melt and add whatever is needed to obtain the desired chemical composition. Manganese, vanadium, and chromium are frequent additives. The properties of the finished steel depend upon the amount of carbon left in and upon the identity and the quantity of other added elements. Soft steel, for example, contains 0.08-0.18 weight percent carbon structural steel, 0.15-0.25% hard steel ox toot steel, 1-1.2%. 

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