By:
Adrian Kano
Ryan Hagstrom
Jay Jang
Ron Reyes
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A phase or a mixture of phases which has
certain characteristics in a microstructure
Microconstituents are created from different
types of heat treatments
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All the phases are known by specific names
Iron-Carbide or Cementite (Fe3C)
 Ferrite
 Austenite
 Delta-ferrite
 Liquid phase or the liquid solution of Fe and C
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Eutectoid Steel is harder than pure iron
Hypoeutectoid steel is as hard but more ductile
Hypereutectoid steel is brittle
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Annealing, Quenching, and Tempering.
Lower Temperatures allow for a smaller
number of nuclei.
Shape Memory Effect.
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727 degrees Celsius
Quenching to a slightly lower temperature
lowers the driving force of ferrite and
cementite nucleation.
Consequently, the time span for ferrite and
cementite nucleation is longer.
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Pearlite start time (Ps)
Austentite transforms into Ferrite and
Cementite platelets.
Pearlite finish time (Pf)
High temperature means that the diffusion is
fast.
The pearlite will be coarse and the hardness
will be low.
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If quenched to a lower temperature than the
nucleation time is shorter.
The diffusion distances are also smaller.
Pearlite will then be finer and the hardness will
be higher.
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If quenching is lowered even further…
Bainite Start time (Bs)
Bainite Finish time (Bf)
Quenched higher= Coarser, Softer, More
Ductile
Quenched lower= Finer, Harder, Less Ductile
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Quenched below 220 degrees Celsius.
Skips Bainite and Pearlite.
Hardest of the 4.
Most brittle.
Transforms structure.
Tempering must be applied.
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Causes precipitation of equilibrium ferrite in
which very fine cementite particles are
dispersed.
Results in increased ductility at the expense of
hardness.
For Martensitic steel tempering between 450
and 600 degrees Celsius is typically used.
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Influences the martensitic transformation.
Changes the rate at which the piece is cooled.
Rate is doubled by stirring.
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They effect the rate of transformation as well as
the hardness.
If a thick part is quenched from austenite
then…
May result in quench cracks.
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Alloying elements such as Mn,
Si, Ni, Cu, Mo, and V into steel
favorably alter the properties.
Usually under 1 percent.
1st hardenability.
2nd shift in eutectoid
composition.
3rd decrease in eutectoid
temperature.
4th martensitic start and finish
temperatures are reduced.
5th tempering time is reduced.
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Stainless steel is steel
that contains an
addition of at least 12
percent chromium.
Keeps the steel from
corroding or rusting.
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Chinese began manufacturing cast iron 3000
years ago.
Enabled the melting temperature to be reduced
to around 1150 degrees Celsius.
Which gave us a liquid metal that could be
effectively cast.
Raw Cast Iron is called Pig iron.(the material
that flows out of a blast furnace)
Contains carbon above 2.11 percent. For
practical uses 2.5 to 4.5 percent carbon is used.
ADVANTAGES
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Used more because it is the
least expensive metallic
material of all.
Also, has the ability to
dampen mechanical
vibrations.
Frequently used in the
bodies of heavy machines
that require vibration
reduction.
Flows easily when molten.
Allowing the casting
intricate shapes.
Barely shrinks after casting.
DISADVANTAGES
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Very brittle, though
hard.
Very weak in tension.
Should never be used in
the creation of tools.
Especially hammers.
Will shatter when
exposed to a blow.
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Contains 1 to 3 mass percent silicon.
If the Si concentration is lowered or the cooling
rate is increased, the decomposition of the
cementite into graphite and ferrite is
incomplete and the graphite is then
surrounded by cementite.
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Graphite precipitates in spherical particles that
are imbedded in Pearlite
When heated it will increase ductility
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Another type of cast iron which is hard and
brittle
The surface contains the hard phase whereas
the interior transforms into gray cast iron
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Ductility increases by heating in an inert
atmosphere
This results in a high strength and fair ductility
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
What is a microconstituent?
What is the Af temperature?
What is the hardest of the four phases?
Which is more brittle? Hypoeutectoid steel or
Hypereutectoid steel.
Name two of the most common elements for alloying steel?
What is the temperature range for tempering martensitic
steel?
What percent carbon does cast iron have?
What is one advantage and one disadvantage of a gray cast
iron?
Name one of the Iron-Carbon Phases.
In a white cast iron the interior transforms into what?
QUESTIONS 1-7, 9, 10
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A phase or a mixture of phases
which has certain characteristics
in a microstructure.
727 degrees Celsius.
Martensite.
Hypereutectoid.
Manganese, Silicon, Nickel,
Copper, Molybdenum, and
Vanadium.
450C - 600C.
2.5 - 4.5 percent.
Austenite, Ferrite, Delta-Ferrite,
and Liquid phase.
Gray Cast Iron
QUESTION 8
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Disadvantages:
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Very brittle, though hard.
Very weak in tension.
Should never be used in the creation of
tools. Especially hammers.
Will shatter when exposed to a blow.
Advantages:

Used more because it is the least expensive
metallic material of all.

Also, has the ability to dampen mechanical
vibrations.
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Frequently used in the bodies of heavy
machines that require vibration reduction.
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Flows easily when molten. Allowing the
casting intricate shapes.
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Barely shrinks after casting
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Carbon Steels
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High Strength Low Alloy Steels
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Quenched and Tempered Steels
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Heat Treatable Low Alloy Steels
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Chromium-Molybdenum Steels
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Low-carbon steels: Steel alloys that contain up
to 0.30 weight percent C.
Medium-carbon steels: Contain carbon ranges
from 0.30 to 0.60 weight percent and the
manganese from 0.60 to 1.65 weight percent.
High-carbon steels: 0.60 to 1.00 weight percent
C with 0.30 to 0.90 weight percent Mn.
High-Strength Low-Alloy steels (microalloyed
steels): are designed to provide better
mechanical properties than conventional
carbons.
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Good Weldabillity, Formability, Machinability
(rated 55-60%)
0.1%-0.2%: chain, stampings, rivets, nails, wire,
pipe, and where very soft,
0.2-0.3%: structural steels, machine parts, soft
and tough steels.
Low costs most common
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More Machinable (60-70%)
0.3-0.4: lead screws, gears, worms, spindles, shafts,
and machine parts.
0.4-0.5: crankshafts, gears, axles, mandrels, tool
shanks, and heat-treated machine parts.
0.6-0.7: called “low carbon tool steel” and is used
where a keen edge is not necessary, but where
shock strength is wanted. Drop hammers dies, set
screws, screwdrivers, and arbors.
0.7-0.8: tough and hard steel. Anvil faces, band
saws,hammers, wrenches, cable wire, etc.
Good toughness and ductility. Balanced
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Toughness, Formabillity, Hardenability, and
Weldability are Low
0.8-0.9: rock drills, shear blades, cold chisels, rivet
sets, and many hand tools.
0.9-1.0: used for hardness and high tensile
strength, springs, cutting tools, press tools, and
striking dies.
1.0-1.3: drills, taps, milling cutters, knives, cold
cutting dies, wood working tools
1.3-1.4 used where a keen cutting edge is
necessary, razors, saws, and where wear resistance
is important
Hardness is high and wear resistant
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Greater Strength-to-weight Ratio than low
carbon steels
Developed primarily for automotive industry
Low carbon (.05-.25%) with Manganese up to
2% and small quantities chromium, nickel,
molybdenum, copper, nitrogen, vanadium,
niobium, titanium and zirconium are used in
various combinations
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Carbon
Manganese
Phosphorus
Sulfur
Silicon
Copper
Lead
Boron
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Chromium
Nickel
Molybdenum
Aluminum
Zirconium
Niobium
Titanium
Vanadium
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Stainless steel is defined as a steel alloy with a
minimum of 10% Chromium.
However resistance in air is usually achieved at
13%.
Chromium in stainless steel forms a layer of
chromium oxide. ( very thin )
Impervious to water and air
Passivation
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There are over 150 grades of stainless steel.
Classified by crystal structure:
Austenitic: over 70% of stainless steel
production.
Ferritic: highly corrosion resistant but less
durable than austenitic
Martenistic: not as corrosion resistant, but
much tougher
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Stainless steel is 100% recyclable and has
antibacterial properties.
Stainless steel is not “invulnerable”
ART WORK AND BUILDING
FACADES DUE TO HIGH SHEEN
ST.LOUIS GATEWAY
ARCH (LEFT)
WALT DISNEY CONCERT
HALL
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Suspension bridges
have been around
since antiquity
Modern suspension
bridges made up of
concrete slabs on top
of steel plates with
steel reinforced
towers and held up by
steel cables
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Built 1928 spanning
the Ohio River
Steel body frame with
and steel eyebars and
cable
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Fatigue failure in
eyebar causes collapse
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Built between 1938
and July 1940
Nicknamed
“Galloping Gertie
Collapsed November
1940
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http://www.youtube.com/watch?v=jzczJXSxnw
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Weak rivets in part to blame for the sinking of
the titanic.
Roughly 3 million rivets used to keep the
titanic together.
Iron used to rivets were No.3 bar (known as
best), the standard was No.4.
•Rivets used on the
titanic contained 3
times the accepted
amount of slag in iron.
•Rivet head’s broke,
letting in ice water
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If quality iron had been used for the rivets the
section of the titanic might not have sunk.
http://www.youtube.com/watch?v=TswFzW
Tv7qc
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Which element is the primary hardening element?
What is fully-killed steels?
What is a solid solution of carbon in alpha-iron?
What weight percent chromium is needed for oxidationresistance in room temperature? In harsh environments?
What is the key element in stainless steel?
What is the layer that protects stainless steel from corrosion
called?
What is the name of the process that makes stainless steel so
durable?
Which elements kill steels?
Austenitic stainless steel makes up ____% of total steel alloy
production.
Stainless steel is ____% recyclable.