文档介绍：英文原文: Steels
Steel is one of the most valuable metals known to man; approximately 200 million tons can be produced in the United States annually. In 1900, US capacity was but 21 million tons. Although the process of steelmaking is familiar to most engineers, a review of this process would be appropriate at this time.
Iron ore, limestone, and coal are the principal raw materials used in making iron and steel. Coke is produced by heating bituminous coal in special ovens. Skip cars go up the skip hoist with loads of iron ore, coke, and limestone and dump them into the top of the blast furnace. Hot air from the stove is blown into the furnace near the bottom. This causes the coke to burn at temperatures up to 3000°F. The ore is changed into drops of molten iron that settle to the bottom of the blast furnace. The limestone that has been added joins with impurities to form a slag that floats on top of the pool of liquid iron. Periodically , the molten iron is drained into a ladle for transporting to either the Bessemer converter, electric furnace or open-hearth furnace. The slag is removed separately so as mot to contaminate the iron.
The making of steel from iron involves a further removal
of impurities. Regardless of which process is used for making steel-open-hearth, Bessemer-converter, or electric-furnace-steel scrap is added along with desired alloying elements and the impurities are burned out.
Liquid steel removed from the furnace is poured into ingot molds. The ingots are then removed to “soaking pits” where they are brought to a uniform rolling temperature.
At the rolling mill, the white-hot steel passes through rolls that form the plastic steel into the desired shape: blooms, slabs, or billets. These three semifinished shapes then go to the finishing mills where they are rolled into finished forms as structural steel, plates and sheets, rods, and pipes.
Steel is the basic and most valuable material used in apparatus manufactured today. Its application is