Module 4.ppt

Effects and importance of making alloy steels
• Alloy steels are steels containing carbon and other
metals added specifically to improve the properties of
the steel.
• Major benefits of alloying steel are:
– Very high hardness throughout the section.
– More controllable quenching with minimum risk of
shape distortion or cracking.
– Improved impact resistance at high temperature
range.
– Improved corrosion resistance.
– Improved high temperature performance

Effects on steel containing following
elements
 MOLYBDENUM
 VANADIUM
 TUNGSTEN
 COBALT
 SILICON
 COPPER
 LEAD
 NICKEL
 CHROMIUM

Effects on steel containing molybdenum
• A carbide former, prevents brittleness & maintains the
steel's strength at high temperatures.
• Molybdenum is what gives those steels the ability to
harden in air.
• It adds greatly to the penetration of hardness and
increases toughness of an alloy.
• It causes steel to resist softening at high temperatures,
which defeats the purpose of forging.
• If the alloy has below 0.020 percent Molybdenum (Mo)
then this alloy can forge with little difficulty.

• Molybdenum is used very widely because of its
powerful effect in increasing hardenability .
• It also raises the temperature at which softening
takes place on tempering and increases resistance
to creep.
• In high speed steel it can be used to replace
approximately twice its weight of tungsten.
• The corrosion resistance of stainless steel is
improved by molybdenum additions.
• Its has got application in turbine rotors and other
large articles, since molybdenum tends to minimize
temper brittleness and thus reducing mass effect.

Effects on steel containing vanadium
• It is basically a Ferrite Promoter & Carbide and Nitride
Former.
• Vanadium acts as a scavenger for oxides, forms
vanadium carbide (VC), and has a beneficial effect on
the mechanical properties of heat-treated steels,
especially in the presence of other elements.
• It slows up tempering in the range of 500-600°C and
can induce secondary hardening.
• Chromium-Vanadium (0.15%) steels are used for
locomotive forging, automobile axles, coil springs,
torsion bars and creep resistance.

• Vanadium increases the yield strength and the tensile
strength of carbon steel.
• The addition of small amounts of Vanadium can
significantly increase the strength of steels.
• Vanadium is one of the primary contributors to the
precipitation in strengthening micro alloyed steels.

Effects on steel containing tungsten
• It is used as an alloying element in tool steels as it tends
to impart a tight, small, and dense grain pattern and
keen cutting edges when used in relatively small
amounts.
• It will also cause steel to retain its hardness at higher
temperatures and hence will have a detrimental effect
upon the steel's forge ability (otherwise known as "red
hard")
• When combined properly with chromium or
molybdenum, tungsten will make the steel to be a high-
speed steel.
• It has found useful application in valves and other steels
which are to be used at high temperatures.

Effects on steel containing cobalt
• Increases strength and hardness, permits quenching at
higher temperatures.
• In some steels used for nuclear engineering cobalt is an
undesirable impurity, even in amounts as small as
0·02%.
• Unlike most other alloying elements cobalt reduces
hardenability.
• It raises the red hardness of steel and this is the reason
for adding 5% to 10% cobalt to certain types of high
speed steels, developed for the specific purpose of
cutting exceptionally hard materials.
• Heat resisting alloys with high cobalt contents have been
developed for use in gas turbines.
• Cobalt is added to the extent of up to 40 % to magnet
steels requiring high coercive force .

Effects on steel containing silicon
• It is a Ferrite Former and Encourages Brittleness. It
promotes a ferrite structure.
• It is one of the principal deoxidizers used in steelmaking.
• Silicon is less effective than manganese in increasing
rolled strength and hardness.
• In low-carbon steels, silicon is generally detrimental to
surface quality. Silicon increases the resistance to
oxidation, both at high temperatures and in strongly
oxidizing solutions at lower temperatures.

• It has a beneficial effect upon tensile strength and
improves hardenability of an alloy.
• It has a toughening effect when used in combination with
certain other elements.
• Silicon (Si) is usually added to improve electrical
conductivity of an alloy.

Effects on steel containing copper
• It is an Austenite Former and Impairs Forging.
• Copper (Cu), in significant amounts is detrimental to
hot-working steels.
• It negatively affects forge welding, but does not
seriously affect arc or oxyacetylene welding.
• Copper can be detrimental to surface quality.
• It is beneficial to atmospheric corrosion resistance
when present in amounts exceeding 0.20%.

• High yield point structural steels containing copper, in
association with chromium and appreciable percentages
of silicon and phosphorus have been developed.
• Copper is also added to some stainless steels to
improve corrosion resistance.

Effects on steel containing lead
• It Improves Machinability, Impairs Ductility , Impairs
Toughness and Impairs Creep Strength.
• It increases the machinability of steel and has no effect
upon the other properties of the metal.
• Lead is virtually insoluble in liquid or solid steel.
However, lead is sometimes added to carbon and alloy
steels by means of mechanical dispersion during pouring
to improve the machinability.
• In creep resisting alloys very small amount of lead may
be harmful.

Effects on steel containing nickel
• It increases strength and toughness but is ineffective in
increasing hardness.
• It is generally added in amounts ranging from 1 percent
to 4 percent. In some stainless steels it is sometimes as
high as 20 percent.
• It is used for strength, corrosion resistance, and
toughness.
• Nickel increases the strength of ferrite therefore
increasing the strength of the steel.

• It is used in low alloy steels to increase toughness and
hardenability.
• Nickel also tends to help reduce distortion and cracking
during the quenching phase of heat treatment.
• For stainless steel, the main reason for the nickel
addition is to promote an austenitic structure.
• Nickel generally increases ductility and toughness.
• It also reduces the corrosion rate and is thus
advantageous in acid environments.

Effects on steel containing chromium
• As a hardening element, Chromium is frequently used
with a toughening element such as nickel to produce
superior mechanical properties.
• At higher temperatures chromium contributes to
increased strength.
• Chromium is a strong carbide former.
• Complex chromium-iron carbides go into solution in
austenite slowly; therefore, sufficient heating time must
be allowed for prior to quenching

• Chromium is commonly added to steel to increase
corrosion resistance ,oxidation resistance, hardenability,
or to improve high-temperature strength.
• It is added for wear resistance, hardenability, and (most
importantly) for corrosion resistance.
• This is the most important alloying element in stainless
steels. It is this element that gives the stainless steels
their basic corrosion resistance. The corrosion
resistance increases with increasing chromium content.

Introduction
•Cast Iron is an iron-carbon alloy with a
typical carbon content of 3.0-4.5 wt. %.
•A similarity among all cast is that they have
carbon contents higher than about 2% and
one with lower carbon contents considered
steels.
•The properties of the cast iron are affected
by the following factors:
– Chemical composition of the iron
– Rate of cooling of the casting in the mold
– Type of graphite formed (if any)

• Advantages:
– Low production cost
– Good machinability without burring
– Ability to cast into complex shapes
– Excellent wear resistance and high hardness
– High inherent damping capabilities

CAST IRON
GRAY MALLEABLE DUCTILE
WHITE
There are four major types of cast iron
1.Gray iron
2.Malleable
3.White
4.Ductile/ Nodular/ Spheroidal graphite irons
Classifications

Gray iron
• Gray cast iron is characterized by the presence
large portion of carbon in the from of graphite
flakes.
• Chemical composition of gray iron ranges from
2-4% total carbon with at least 1% silicon.
• The Si aids graphite formation.
• Microstructure of ferrite, pearlite or martensite.
• A ferrite matrix yields low strength gray iron; a
pearlite matrix, higher strength .

• Physical properties
– As it contains 10% by volume of graphite ,it
said to have high damping capacity.
– It has high electrical resistivity.
– The corrosion resistance is better than steel.
• Mechanical properties
– It has low tensile strength, ductility&
toughness since being brittle.
– On the other hand the compressive strength.
– It doesn't obeys Hooke’s law.

• Application:
– Gray cast iron widely used for piping systems
– Gray cast iron has nearly all the properties that are
desired for rotor applications, Heavy duty structures,
cast iron cookware and disc brake rotors.
– Buildings, bridges.
– It finds extensive use in making valve plates for
refrigeration compressors.
– Automotive brake cylinders and hydraulic valve
bodies.
– Engine cylinder blocks, flywheels, gears, machine-
tool bases.

Malleable iron
• Malleable iron that has been thermally treated so
it has significant ductility.
• Malleable iron-carbon-silicon alloy, with 2-
3%carbon& 1-1.8%silicon.
• Microstructure of pearlite & free cementite.
• It made by converting white to ferrite or pearlite
matrix ,in which carbon present in the form of
flower like nodules called temper carbon.
• Two conversion stages (1)first stage of
graphitization (2)second stage of graphitization.

temp
time
Critical temp
Slow heat up
Dissolve free cementite
Temper carbon
Air cooled or
quenched

• Properties:
– Physical properties are similar to those gray
iron.
– The ductility is the major difference offering
20% elongation without breaking.
– The machinability is excellent due to tamper
carbon.
• Applications:
– It is used in differential & steering gear
housing ,break pedals, tractor springs, hanger
&washing machine parts

Ductile iron / Nodular/ Spheroidal
graphite irons
• Gray iron are specially treated to produce
graphite in the form of small nodules.
• Chemically, the carbon ranges of 3-4% & silicon
in the range 2-3%.
• Many ductile iron contain significant nickel
addition.
• Formation of nodular iron is accomplished by
magnesium addition.
• Other materials such as ferrosilicon are added to
promote graphitization and to control nodular
size.

• Application
– The automotive and agricultural industries are
the major users of ductile iron castings.
– Ductile iron is used for such critical
automotive parts as crankshafts, engine
connecting rods, idler arms, wheel hubs, truck
axles, front wheel spindle supports, disk brake
calipers, suspension system parts, power
transmission yokes
– High temperature applications for turbo
housing and manifolds,
– High security valves for many applications.
Gears, camshafts, crankshafts.

White iron
• White iron get their name from their white
appearance.
• It contains carbon in the range from 2-4%,silicon
from0.5-2% & manganese about 0.5%
• A microstructure of free cementite & fine pearlite,
possibly with some austenite.
• Gray iron will form white iron when cooled
rapidly from casting temp. called chilled iron.

• Properties:
– Hard ,brittle and cannot be machined.
– Highly resistance to wear.
– Tensile strength is good.
– Due to poor fluidity it doesn't fill mould freely.
• Application:
– Railway brake block, rolls, wear plate,
pumping linings, balls.

Introduction
• High speed steel (often abbreviated HSS, sometimes
HS) is a material usually used in the manufacture of
machine tool bits and other cutters.
• It is often used in power saw blades and drill bits.
• It can withstand higher temperatures without losing its
temper (hardness).
• This property allows HSS to cut faster than high carbon
steel, hence the name high speed steel.
• At room temperature, in their generally recommended
heat treatment, HSS grades generally display high
hardness and a high abrasion resistance (generally linked
to tungsten content often used in HSS) compared to
common carbon and tool steels.

HSS compositions
• A new high speed steel composition and article are
provided consisting essentially of about:
– 1.20% to 1.40% of carbon,
– 0.50% maximum manganese,
– 1.00% maximum silicon,
– 3.5% to 4.5% chromium,
– 2.25% to 2.75% vanadium,
– 5.60% to 6.40% tungsten,
– 5.60% to 6.40% molybdenum,
– 5.0% to 7.0% cobalt,
– 0.02% to 0.08% nitrogen
– and the balance essentially iron, said high speed steel
composition having a ratio of cobalt to equivalent tungsten of
about 0.12 to 0.26 and a ratio of vanadium to carbon of 1.7 to
2.1, said composition and article being characterized by
extremely high hardness and toughness coupled with resistance
to brittleness and breakage.

Types of HSS
• High speed steels belong to the Fe-C-X multi-component
alloy system where X represents chromium, tungsten,
molybdenum, vanadium, or cobalt.
• Generally, the X component is present in excess of 7%,
along with more than 0.60% carbon. (However, their
alloying element percentages do not alone bestow the
hardness-retaining properties; they also require
appropriate high-temperature heat treatment in order to
become true HSS
• The addition of about 10% of tungsten and molybdenum
in total maximises efficiently the hardness and
toughness of high speed steels and maintains these
properties at the high temperatures generated when
cutting metals.

M42
• M42 is a HSS alloy made up of roughly 8%
cobalt.
• It is widely used in metal manufacturing because
of its ability to resist wear over conventional high
speed steels, allowing for shorter cycle times in
production environments due to higher cutting
speeds or from the increase in time between tool
changes.
• M42 is also less prone to chipping when used
for interrupted cuts and cost less when
compared to the same tool made of carbide.
• Tools made from high speed steel and cobalt
can often be identified by the letters HSS-Co.

Applications
• The main use of high speed steels continues to be in the
manufacture of various cutting tools: drills, taps, milling
cutters, tool bits, gear cutters, saw blades, etc., although
usage for punches and dies is increasing.
• High speed steels also found a market in fine hand tools
where their relatively good toughness at high hardness,
coupled with high abrasion resistance and fine, made
them suitable for low speed applications requiring a
durable keen (sharp) edge, such as files, chisels, hand
plane blades, and high quality kitchen and pocket knives.

Introduction
• Aluminium is silvery white and ductile member of the
boron group of chemical elements.
• The chief source of aluminium is bauxite ore.
• Aluminium is remarkable for its ability to resist corrosion
due to the phenomenon of passivation and for the
metal's low density.
• Structural components made from aluminium and its
alloys are vital to the aerospace industry and very
important in other areas of transportation and building.

Properties of Aluminium
• Light Weight
– Aluminium is a very light metal with a specific weight
of 2.7 g/cm3, about a third that of steel.
– For example, the use of aluminium in vehicles
reduces dead-weight and energy consumption while
increasing load capacity.
• Corrosion Resistance
– Aluminium naturally generates a protective oxide
coating and is highly corrosion resistant.
– Different types of surface treatment such as
anodising, painting or lacquering can further improve
this property.
– It is particularly useful for applications where
protection and conservation are required.

• Electrical and Thermal Conductivity
– Aluminium is an excellent heat and electricity
conductor and in relation to its weight is almost twice
as good a conductor as copper.
– This has made aluminium the most commonly used
material in major power transmission lines.
• Reflectivity
– Aluminium is a good reflector of visible light as well as
heat, and that together with its low weight, makes it
an ideal material for reflectors in, for example, light
fittings or rescue blankets.

• Ductility
– Aluminium is ductile and has a low melting point and
density.
– Its ductility allows products of aluminium to be
basically formed close to the end of the product’s
design.
• Impermeable and Odourless
– Aluminium foil, even when it is rolled to only 0.007 mm
thickness, is still completely impermeable and
odourless .
– Moreover, the metal itself is non-toxic and releases
taste substances which makes it ideal for packaging
sensitive products such as food or pharmaceuticals.

• Recyclability
– Aluminium is 100 percent recyclable with no
downgrading of its qualities.
– The re-melting of aluminium requires little energy.

Applications of Aluminium
• Transportation (automobiles, aircraft, trucks, railway
cars, marine vessels, bicycles etc.) as sheet, tube,
castings etc.
• Packaging (cans, foil, etc.)
• Construction (windows, doors, siding, building wire,
etc.)
• A wide range of household items, from cooking
utensils to baseball bats, watches and notebook
computers (Apple)
• Street lighting poles, sailing ship masts, walking
poles etc.

• Outer shells of consumer electronics, also cases for equipment
e.g. photographic equipment.
• Electrical transmission lines for power distribution
• In Alnico magnets and cryogenic applications
• Substrate material of metal-core copper clad laminates used in
high brightness LED lighting.

Aluminium Alloys
• Aluminium alloys are mixtures of aluminium with other
metals (called an alloy), often with copper, zinc,
manganese, silicon, or magnesium. They are much
lighter and more corrosion resistant than plain carbon
steel,
• The strength and durability of aluminium alloys vary
widely, not only as a result of the components of the
specific alloy, but also as a result of heat treatments and
manufacturing processes
• One important structural limitation of aluminium alloys is
their fatigue strength. Unlike steels, aluminium alloys
have no well-defined fatigue limit, meaning that fatigue
failure will eventually occur under even very small cyclic
loadings

• Aluminium Alloys can be classified as
follows:
– Wrought alloys
– Cast alloys
– Heat –treatable alloys
– Non-heat –treatable alloys

Applications of Aluminium Alloys
• Aluminium alloys are commonly used in aircraft and
other aerospace structures.
• Alloys are used for boat building and shipbuilding, and
other marine and salt-water sensitive shore applications.
• Architectural and ornamental applications

Duralumin
• It contains
Cu -3.5%-4.5% , Mn - .4%-.7% ,
Mg - .4%-.7% , Fe -<.7%, Al – balance
• Properties:
– High machinability
– High tensile strength
– Excellent casting and forging properties
• Uses:
– Aircraft and automobile parts
– As bars , sheets, tubes and rivets

Introduction
• Beryllium is the chemical element with the symbol Be
and atomic number 4.
• A bivalent element, beryllium is found naturally only
combined with other elements in mineral.
• Beryllium is very low density (1.85 times that of water),
high melting point (1278 °C), high temperature stability,
and low coefficient of thermal expansion.

Properties of Beryllium
• Non magnetic in nature
• Stiff
• Light weight and has high rigidty
• It shows dimensional stability over wide range of temperature
• Toxic and its inhalation can cause lung cancer
• Good conductor of electricity and excellent thermal
conductivity

Application of Beryllium
• Due to its stiffness, light weight, and dimensional stability
over a wide temperature range, beryllium metal is used
for lightweight structural components in the defense and
aerospace industries in high-speed aircraft, missiles,
space vehicles and communication satellites.
• Due to its non-magnetic properties, Beryllium-based tools
are used for maintenance and construction near MRI
scanners.

• Beryllium's characteristics (low weight and high rigidity)
make it useful as a material for high-frequency drivers
• It is used as a ideal aerospace material
• It is used in rocket nozzles and is a significant
component of planned space telescopes.
• It has found application in particle physics experiments.
• It is used in nuclear systems, aircraft brakes , and in
satellite parts

Beryllium Alloy
• Beryllium copper, also known as copper beryllium, BeCu
or beryllium bronze, is a metal alloy of copper and 0.5 to
3% beryllium,
• The thermal conductivity of these alloys lies between
steels and aluminium
• Beryllium-copper alloys are used in a wide variety of
applications because of their combination of high
electrical and thermal conductivity, high strength and
hardness, nonmagnetic properties, along with good
corrosion and fatigue resistance.
• These applications include the making of spot-welding
electrodes, springs, non-sparking tools and electrical
contacts.

Introduction
• Copper is a chemical element with the
symbol Cu and atomic number 29.
• It is a ductile metal with very high thermal
and electrical conductivity.
• Pure copper is rather soft and malleable
and a freshly-exposed surface has a
pinkish or peachy color.
• It is used as a thermal conductor, an
electrical conductor, a building material,
and a constituent of various metal alloys.

Characteristics
• Colour
– Copper just above its melting point keeps its pink
luster color when enough light outshines the orange
incandescence color.
– Copper has a reddish, orangish, or brownish color
because a thin layer of tarnish (including oxides)
gradually forms on its surface when gases (especially
oxygen) in the air react with it.
– But pure copper, when fresh, is actually a pinkish or
peachy metal.
• Occurrence
– Copper can be found as native copper in mineral form

• Mechanical properties
– Copper is easily worked, being both ductile and
malleable.
– Copper can be machined, although it is usually
necessary to use an alloy for intricate parts, such as
threaded components, to get really good
machinability characteristics.
– Good thermal conduction makes it useful for
heatsinks and in heat exchangers.
– Copper has good corrosion resistance, but not as
good as gold.
– It has excellent brazing and soldering properties and
can also be welded, although best results are
obtained with gas metal arc welding.
– Copper is normally supplied, as with nearly all metals
for industrial and commercial use, in a fine grained
polycrystalline form.

• Electrical properties
– Copper has the second highest electrical conductivity
of any element, just after silver.
– This high value is due to virtually all the valence
electrons (one per atom) taking part in conduction.
– The resulting free electrons in the copper amount to a
huge charge density of 13.6x109 C/m3.
– This high charge density is responsible for the rather
slow drift velocity of currents in copper cable (drift
velocity may be calculated as the ratio of current
density to charge density).

Copper alloys
• Copper alloys are alloys with copper as their principal
component. They have high resistance to corrosion.
• Due to its high electric conductivity, pure electrolytic
copper is used mostly for making of electrical cables.
• The similarity in external appearance of the various
alloys, along with the different combinations of elements
used when making each alloy, can lead to confusion
when categorizing the different compositions.
• There are as many as 400 different copper and copper-
alloy compositions loosely grouped into the categories:
– copper, high copper alloy, brasses, bronzes, copper nickels,
copper–nickel–zinc (nickel silver), leaded copper, and special
alloys.

Brasses
• A brass is an alloy of copper with zinc.
• Brasses are usually yellow in color.
• The zinc content can vary between few % to
about 40%; as long as it is kept under 15%, it
does not markedly decrease corrosion
resistance of copper.
• Brasses can be sensitive to selective leaching
corrosion under certain conditions, when zinc is
leached from the alloy (dezincification), leaving
behind a spongy copper structure.

Bronzes
• A bronze is an alloy of copper and other metals, most
often tin, but also aluminium and silicon.
• Aluminium bronzes are alloys of copper and aluminium.
The content of aluminium ranges mostly between 5-11%.
Iron, nickel, manganese and silicon are sometimes
added. They have higher strength and corrosion
resistance than other bronzes, especially in marine
environment, and have low reactivity to sulfur
compounds. Aluminium forms a thin passivation layer on
the surface of the metal.
• Phosphor bronze
• Nickel bronzes, e.g. nickel silver and cupronickel

Application
• Architecture: Copper and copper alloy materials are
used in all aspects of architecture, both exterior and
interior.
• Automotive: Copper is an essential component of many
of the latest design elements in cars.
• Electrical: Copper's high conductivity makes it the ideal
material in a wide variety of electrical applications
including:
– Electrical Energy Efficiency
– Power Quality
– Building Wire
• Tube, Pipe & Fittings: Copper tube is the highest quality
material available today for a variety of building
applications including plumbing, fire sprinklers.

• Fuel Gas: Copper tube is an excellent choice for natural
gas piping systems.
• Industrial: Copper serves as an essential material in a
vast number of industries including electronics.
• Seawater: Copper's unique properties make it ideal for
many applications in the harsh environments of marine.
• Machined Products: Copper alloy rod and bar products
are well suited for this purpose.
• Telecommunications: Communications are the backbone
of today's fast-paced businesses, and copper wiring is at
the core of those systems.

Introduction
• Magnesium is a chemical element with the symbol Mg,
atomic number 12 and common oxidation number +2.
• It is an alkaline earth metal and the ninth most abundant
element in the universe by mass.
• Mg is a silvery white metal and has the lowest density of
the common structural materials.
• Mg has a melting point of 650oC.
• Mg corrodes badly under many conditions and therefore
need to be painted or given some surface finish to avoid
corrosion.

Properties
• Mg alloys possess the following properties:
– High strength to weight ratio.
– Good fatigue strength.
– Good dimensional stability in service.
– Good damping capacity.
– High thermal conductivity.
– Relatively high electrical conductivity.

Magnesium alloys
• Dow metal
– It contains 90% Mg, 10% Al and a small addition of
Mn.
– Dow metal finds applications in auto and aircraft
industries.
– Dow metal is extremely light and can be welded and
machined.

• Wrought alloys
– Wrought magnesium alloys have a special feature.
– They compressive proof strength is smaller than
tensile proof strength.
– After the forming wrought magnesium alloys have
string texture in the deformation direction, which
increase tensile proof strength.
– In compression the proof strength is smaller because
of twinning, which happen more easily in compression
than in tension in magnesium alloys because of the
hexagonal lattice structure.

Application
• For making parts such as airframes, engines, gear
boxes, flooring, seating for aeroplanes, helicopters,
missiles and satellites.
• For material handling equipments such as hand trucks,
barrel skids, grain shovels, gravity conveyors, foundry
equipments.
• Moving parts of textile machines and printing equipment.
• Furniture, ladders and lawn movers.
• Typewriters, dictating machines, calculators
• Binocular and camera bodies.
• In the production of Uranium, Beryllium, Zirconium,
Titanium etc.

Introduction
• Belongs to the transition group in the fourth series of the
periodic table.
• Atomic number of 28, an Atomic weight of 58.71, Density
8.908g/cu cm at 0ο
C at melting point of 1453 ο
C.
• Crystallographic system is F.C.C. at all temperatures.
• Commercial grade of wrought nickel (‘A’ nickel) contains
99.0% nickel + 0.4% cobalt and reported as 99.4%
nickel.
• Commercially pure nickel is hard as low-carbon steel.
Nickel work- hardens rapidly when cold worked.

Properties
• Melting point…….1453οC.
• Density, gm/cu cm, at 20οC…….8.908
• Tensile strength…….65000 to 115000 psi (From hot
rolled (4565 to 8075 kg/cm2) to cold drawn)
• Hardness RB ……..40 to 100 (depending upon whether
Ni is hot rolled annealed or cold drawn).
• Resistance to corrosion.
• It is a hard lustrous white metal.
• Possesses good corrosion and oxidation resistance.
• It has high tensile strength and can be easily formed hot
or cold.
• Can take up high polish.
• Can be fabricated using processes similar for mild steel.
• Is ferromagnetic at ordinary and low temperatures but
becomes paramagnetic at elevated temperatures.

Applications
• For corrosion protection of iron and steel parts and Zn-
base die castings used in the automotive field.
• In the chemical, soap, caustic and allied industries for
construction of evaporators, tanks, jacketed kettles,
heating coils, tubular condensers and many other
processing equipments.
• As an alloying element in both ferrous and non ferrous
alloys.
• Nickel is a strong austenite stabilizer and with chromium
is used to form the important AISI 300 series of non
magnetic austenitic stainless steels.

• As a coating for parts subjected to corrosion and wear.
Therefore the second important use of nickel is in
electroplating.
• In the incandescent lamp and radio industries.
• In electronic (vacuum electronic tubes) and low-current
electrical applications.
• As permanent magnets.
• As anodes in low-tubes and in photocells.
• As thermocouple material.

Nickel-iron alloys
• They possess thermal-expansion and magnetic
charceteristics of commercial importance.
• Invar(40-50% nickel) is the Trademark and is
charecterised by an extremely low coefficient of
thermal expansion which is used for making
precision instruments, measuring tapes, weights
etc.
• Adding 12% chromium, in some of the iron
produces an alloy (Elinvar) with an invariable
modulus of elasticity over a considerable
temperature range as well as a fairly low
coefficient of expansion

Nickel-copper alloys
Monel (66% ni; 31.5%Cu, 1.35%Fe, 0.90% Mn,)
• Properties
• Brighter appearance than nickel,
• Stronger and tougher than mild steel.
• Excellent resistance to atmospheric and sea-water
corrosion than nickel
• Less resistant to alkalies and salts.
• Uses
• Used in architectural and marine applications where
appearance and corrosion resistance is important in
specialized equipment used by the food, pharmaceutical,
paper, oil and chemical industries

Constantan (45% Ni and 55% Cu).
• Properties
• Highest electrical resistivity
• Lowest temperature coefficient of resistance and
• Highest thermal emf against platinum, of any of the
copper- nickel alloys.
• Uses
– Electrical resistors
– Thermocouples
– Wheatstone bridges, etc.

Ni-cu-zn ALLOYS
• Nickel-copper-zinc alloys though known as nickel-silver,
do not contain silver, and is actuality they are brasses
with sufficient nickel added to give a silvery white colour,
improved corrosion resistance and high strength.
• These alloys are used as low cost substitutes for silver in
tableware and jewellery, usually with a silver or gold
electroplate on the surface.
• Nickel silvers are also construction materials for many
musical, drafting, and scientific instruments and are also
used for marine and architectural applications.

Ni-Cr ALLOYS
• Nickel-chromium alloys with or without iron , form
a series of corrosion and heat-resistant materials.
• The 80% Ni, 20% Cr alloy (Chromel A, Nichrome
V, Tophet A) and the 60% Ni, 16% Cr, 24% Fe alloy
(Nichrome, Chromel C, Tophet C) form the bulk of
materials used for heater elements .
• The 90% Ni, 10% Cr (Chromel P) alloy in
combination with alumel is much used as a
dependable base-metal thermocouple.

Super alloys
• The superalloys have superlative combinations
of properties.
• These materials are classified according to the
predominant metal in the alloy, which may be
cobalt, nickel or iron. Other alloying elements
include the refractory metals (Nb, Mo, W, Ta)
chromium and titanium.
• Super alloys are atleast five times as strong as
steels routinely used for making bridges and
large buildings.
• They can withstand enormous strains and
exhibit remarkable resistance to metal fatique.
They posses high impact strength and superior
strength to mass ratio.

• They are probably the toughest materials
ever produced.
• Super alloys are used in aircraft turbine
components, which must withstand exposure
to severely oxidizing environments and high
temperatures for reasonable time periods.
• Mechanical integrity under these conditions is
critical; in this regard.
• Density is an important consideration
because centrifugal stresses are diminished
in rotating members when the density is
reduced.

Module 4.ppt

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