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Daniel Ballard Presents- Making Alloy

STEEL MAKING

Steel-making is the second step in producing steel from iron ore. In this stage, impurities such as sulfur, phosphorus, and excess carbon are removed from the raw iron, and alloying elements such as manganese, nickel, chromium and vanadium are added to produce the exact steel required.

Older processes

Bethlehem Steel in Bethlehem, Pennsylvania was one of the world's largest manufacturers of steel before its 2003 closure.

The earliest means of producing steel was in a bloomery. Early modern methods of producing steel were often labor-intensive and highly skilled arts. See:

• finery forge, in which the German finery process could be managed to produce steel.
• blister steel and crucible steel.

An important aspect of the industrial revolution was the development of large-scale methods of producing forge-able metal (bar iron or steel). The puddling furnace was initially a means of producing wrought iron, but was later applied to steel production.
The real revolution in steel-making only began at the end of the 1850s. The Bessemer process was the first successful method of steel-making in quantity, followed by the open hearth furnace.

Modern processes

Modern steel-making processes are broken into two categories: primary and secondary steelmaking. Primary steel-making uses mostly new iron as the feedstock, usually from a blast furnace. Secondary steel-making uses scrap steel as the primary raw material. Gases created during the production of steel can be used as a source of power.^[1]

Primary steel-making

Main article: Basic oxygen steel making

Basic oxygen steel making is a method of primary steel making in which carbon-rich molten pig iron is made into steel. Blowing oxygen through molten pig iron lowers the carbon content of the alloy and changes it into low-carbon steel. The process is known as basic due to the pH of the refractories—calcium oxide and magnesium oxide—that line the vessel to withstand the high temperature of molten metal.
The process was developed in 1948 by Robert Durrer and commercialized in 1952–1953 by Austrian VOEST and ÖAMG. The LD converter, named after the Austrian towns Linz and Donawitz (a district of Leoben) is a refined version of the Bessemer converter where blowing of air is replaced with blowing oxygen. It reduced capital cost of the plants, time of smelting, and increased labor productivity. Between 1920 and 2000, labor requirements in the industry decreased by a factor of 1,000, from more than 3 worker-hours per tonne to just 0.003. The vast majority of steel manufactured in the world is produced using the basic oxygen furnace; in 2000, it accounted for 60% of global steel output. Modern furnaces will take a charge of iron of up to 350 tons and convert it into steel in less than 40 minutes, compared to 10–12 hours in an open hearth furnace.

Secondary steel making

Main article: Electric arc furnace

Secondary steelmaking is most commonly performed in an electric arc furnace.

HIsarna steel making

Main article: HIsarna steel making process

The HIsarna steel making process is a process for primary steel making in which iron ore is processed almost directly into steel. The process is based around a new type of blast furnace called a Cyclone Converter Furnace, which makes it possible to skip the process of manufacturing pig iron pellets that is necessary for the basic oxygen steel making process. Without the necessity for this preparatory step the HIsarna process is more energy-efficient and has a lower carbon footprint than traditional steel making processes.

MAKING STEEL.