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Iron & Steel 2013-01-23[back]

Iron & Steel

Harder - The exact date at which people first discovered how to smelt iron ore and produce usable metal is not known. Archaeologists have found early iron tools that were used in Egypt from about 3000 bc. Iron objects of ornamentation were used even earlier. By about 1000 BC, the ancient Greeks are known to have used heat treatment techniques to harden their iron weaponry. These historical iron alloys, all iron alloys produced until about the fourteenth century ad, were forms of wrought iron.
Wrought iron was made by first heating a mass of iron ore and charcoal in a forge or furnace using a forced draft of air. This generated enough heat to reduce the iron ore to a hot, glowing, spongy mass of metallic iron filled with slag materials. The slag contained metallic impurities and charcoal ash. This iron sponge was then removed from the furnace and while still glowing hot, it was pounded with heavy sledges to separate the slag impurities and to weld and form the purer mass of iron. The iron produced in this way almost always contained slag particles and other impurities, but occasionally this technique of small batch iron making yielded a true steel product rather than wrought iron. These early iron makers also learned to make steel by reheating wrought iron and charcoal in clay boxes for several days, until the iron absorbed enough carbon to become a true hardened steel.
By the end of the fourteenth century, iron furnaces used in smelting were becoming larger with increased draft from large bellows being used to force air through the “charge” (mixture of raw materials). These larger furnaces first freed the molten iron in its upper levels. This metallic iron then combined with higher amounts of carbon because of the heated combustion blast produced by the air forced up through the furnace. The product of these furnaces was pig iron, an alloy that melts at a lower temperature than steel or even wrought iron. Pig iron was then further processed to make steel.
Today, giant steel mills are essential for producing steel from iron ore. Steel making still uses blast furnaces that are merely refinements of the furnaces used by the old ironworkers. Improvements in the refinement of molten iron with blasts of air was accomplished by the 1855 Bessemer converter. Since the 1960s, electric arc furnaces have also been producing steel from scrap metal.
All right:Suzhou Sugulong Metallic Products Co., Ltd　　　　　 Address: ShangHu Town, Changshu City, Jiangsu Province, 215553, China