Civil Engineering Reference
In-Depth Information
Iron ore
Coke
Limestone
Blast
furnace
Slag
Pig iron
casting
Pig iron
Open
hearth
furnace
Basic
oxygen
furnace
Electric
arc
furnace
Alloying
agents
Molten
steel
Continuous
casting
Soaking
pits
Primary
rolling
Ingots
Structural
shapes
Rails
Bars
Wires
Pipes
Plates
Sheets
FIGURE 3.3
Conversion of raw material into different steel shapes.
basic oxygen furnaces are the industry standard for high-production mills.
A basic oxygen furnace can refine 280,000 kg (300 tons) of steel in 25 min-
utes, compared with the eight hours it takes to refine the same quantity of
steel in an open hearth furnace.
Electric furnaces use an electric arc between carbon electrodes to melt
and refine the steel. These plants require a tremendous amount of energy
and are primarily used to recycle scrap steel. Electric furnaces are frequent-
ly used in minimills, which produce a limited range of products. In this
process, molten steel is transferred to the ladle. Alloying elements and ad-
ditional agents can be added either in the furnace or the ladle.
During the steel production process, oxygen may become dissolved in the
liquid metal. As the steel solidifies, the oxygen can combine with carbon to
form carbon monoxide bubbles that are trapped in the steel and can act as ini-
tiation points for failure. Deoxidizing agents, such as aluminum, ferrosilicon
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