Section 11.4- Iron Flashcards
the fourth most abundant element found in the earth’s crust
iron
second most abundant metal
iron
iron occurs in the crust in several ores, such as
hematite, magnetite, siderite, pyrite
iron is soft and silvery white as a pure metal; in moist air it quickly reacts with oxygen (rusts) to form reddish-brown
iron (III) oxide
since the Middle Ages, the primary method of reducing iron ore to iron metal has been the _________________
a structure consisting of a vertical, heat-resistant furnace column, filled with ore and fuel, in which the chemical reactions take place
blast furnace
coke is another name for
carbon
calcium silicate (CaSiO3) mixes with other impurities to form
is less dense than iron and floats upon it, preventing the reaction of incoming air with molten iron
slag
the molten iron is __________________ (drained from the furnace) through a duct near the furnace’s base
tapped
once molten iron is tapped, it is called
pig iron
if pig iron is cast into molds and cooled, it is known as
cast iron
a fluffy insulation material called _______________ is produced from slag if jets of steam are blown through the molten slag as it cools
mineral wool
alternate method of iron reduction in which natural gas is used to reduce iron ore to sponge iron
direct iron reduction
a solid, powdery form of iron suitable for steelmaking
sponge iron
the most commonly used form of iron
an alloy of iron and a small percentage of carbon
steel
carbon steel with less that .2% carbon that is ductile and malleable
mild steel
carbon steel with .2% to .6% of carbon
medium steel
carbon steel that contains between .6% and 1.5% of carbon
high-carbon steel
steels that contain other metals besides iron
alloy steels
contain a total of 1% to 5% of other alloying metals
low-alloy metals
contain more than 5% of one or more alloying elements in steel
high-alloy steels
a high-alloy steel that is resistant to corrosion
stainless steel
pig iron from blast furnaces is typically refined to steel by the
basic oxygen process
about 60% of steel production in the United States uses the
electric-arc furnace
steel production process in which an electric arc between giant carbon electrodes provides the heat to melt the metal
electric arc furnace
higher temperature is possible with the _________________ than the _____________________ (two processes of steel production)
electric-arc= higher temps
basic oxygen= lower temps
internals stresses and distortions in the metal after it cools can be removed by a process called ________________
heats the steel to 700 C - 800C for up to several hours and then is slowly cooled
annealing
one of the simplest ways to harden a piece of steel
when the metal is bent or hammered into its final shape at relatively low temps
cold working
one of the most common examples of cold working is _________, in which a piece of solid steel is stamped into its final shape by a giant, hammerlike press
cold forging
examples of cold working
- cold forging- hammerlike press
- cold-rolling- heavy rollers
- drawing- pulled through small hole
way in which the hardness of a piece of steel may be altered is
cooling red-hot metal quickly
quenching
if the steel is too brittle after quenching, it may be made less brittle by a process called
steel GENTLY heated to a MODERATE temperature and then allowed to cool
tempering
in cases where both toughness and hardness are desired, a process called __________________ can be used to harden the surface of the steel while leaving the interior resilient
case hardening
alloys of carbon and iron ONLY, containing varying percentages of carbon that are determined by the properties desired
carbon steels
