Characteristics of Steel and Cast Iron.

Metal Properties, Characteristics, Uses, And Codes
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and cast iron (gray and malleable) is the metal, iron in the form of

pig iron. Pig iron is produced from iron ore, which occurs chiefly

in nature as an oxide, the two most important oxides being hematite

and magnetite.

(2) Iron Ore. Iron ore is reduced to pig iron in a blast furnace,

and the impurities are removed in the form of slag (figure 2 on the

following page). Raw materials charged into the furnace include iron

ore, coke, and limestone.

The pig iron produced is used to

manufacture steel or cast iron.

To convert iron ore to iron, the

iron ore is smelted with coke and limestone in a blast furnace

(figure 3 on page 13) to remove from it the oxygen (the process of

reduction) and earth foreign matter.

Limestone is used to combine

with the earth matter to form a liquid slag; coke is used to supply

the chemical element of carbon needed for the reduction and

carburization of the ore.

The iron ore, limestone, and coke are

charged into the top of the furnace. Rapid combustion, with a blast

of preheated air into the smelter, causes a chemical reaction in

which the oxygen is removed from the iron. The iron melts, and the

molten slag, consisting of limestone flux and ash from coke, together

with compounds formed by the reaction of the flux with substances

present in the ore, floats on the heavier iron liquid. Each material

is then separately drawn off.

(3) Plain Carbon Steel. Plain carbon steel consists of iron and

carbon, the latter being the hardening element. Tougher alloy steel

contains other elements, such as chromium, nickel, and molybdenum.

Cast iron is nothing more than basic carbon steel with more carbon

added together with silicon.

The carbon content range for steel is

0.03 to 1.7 percent, and for cast iron 4.5 percent.

(4) Steel.

Steel is produced in a variety of melting furnaces:

open-hearth, Bessemer converter, crucible electric-arc, and induction.

Most carbon steel is made in open-hearth furnaces, while alloy steel is

melted in electric-arc and induction furnaces. Steel, often considered

as the master metal, is available in large quantities in both