The Time Value of Money

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Metals-Ferrous and Non Ferrous
By Engr. Prof. Dr. Attaullah Shah
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Ferrous Metals.

• Ferrous is an adjective used to indicate the
  presence of iron.
• The word is derived from the Latin word ferrum
  "iron").
• Ferrous metals include steel and pig iron (with
  a carbon content of a few percent) and alloys of
  iron with other metals (such as stainless steel).
• The term non-ferrous is used to indicate metals
  other than iron and alloys that do not contain an
  appreciable amount of iron
• All forms of iron and steel / manufactured to
  meet wide variety of specification
• Chemical composition internal structure is
  highly controlled during manufacturing.
• Good strength and hard. Fabricated in shops to
  desired size shape
• Good quality control during manufacturing

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Brief History

• Iron age (12th century BC) (mostly wrought iron)
  weapons made with inefficient smelting methods.
  The best weapons? When iron combined with
  carbon!
• Became more common after more efficient
  production methods were devised in the 17th
  century.
• With invention of the Bessemer process in the
  mid-19th century, steel became a relatively
  inexpensive mass-produced good

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IRON

• Basic constituent of steel.
• Most abundant metallic in the earths crust after
  aluminum
• Found in the form of ores as oxides,
  carbonates, silicates sulfides
• Produced in blast furnaces.
• It can be produced into 3 commercial forms that
  is a) wrought iron b) steel c) cast iron
• Increase in the amount of carbon decreases the
  melting point of the metal.
• Carbon exerts the most significant effects on
  the microstructure and properties of iron
  products.

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Iron Ores

• Iron ores are rocks and minerals from which
  metallic iron can be economically extracted.
• The ores are usually rich in iron oxides and
  vary in color from dark grey, bright yellow, deep
  purple, to rusty red.
• The iron itself is usually found in the form of
  magnetite (Fe3O4), hematite (Fe2O3), goethite
  (FeO(OH)), limonite (FeO(OH).n(H2O)) or siderite
  (FeCO3).
• Hematite is also known as "natural ore", a name
  which refers to the early years of mining, when
  certain hematite ores containing up to 66 iron
  could be fed directly into iron-making blast
  furnaces.
• Iron ore is the raw material used to make pig
  iron, which is one of the main raw materials to
  make steel.
• 98 of the mined iron ore is used to make steel.
  Indeed, it has been argued that iron ore is "more
  integral to the global economy than any other
  commodity, except perhaps oil.

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Pig Iron

• Pig iron is the intermediate product of smelting
  iron ore with a high-carbon fuel such as coke,
  usually with limestone as a flux. Charcoal and
  anthracite have also been used as fuel.
• Pig iron has a very high carbon content,
  typically 3.54.5, which makes it very brittle
  and not useful directly as a material except for
  limited applications.
• The Chinese were making pig iron by the later
  Zhou Dynasty (1122256 BC).
• An ingot is a material, usually metal,
• that is cast into a shape suitable for further
• processing.

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WROUGHT IRON

• Manufactured by melting refining iron to a
  high degree of purity.
• Then, molten metal is poured into a ladle and
  mixed with hot slag.
• The fluxing action of the slag causes a spongy
  mass to form which is processed by rolling
  pressing.
• It is only iron-bearing material containing slag.

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• Its a low carbon steel (less than 0.1 carbon
  by weight) containing a small amount of slag,
  usually less than 3.
• It contains small amount of manganese (less than
  0.1) and silicon (0.2).
• Its ductility is lower than steel.
• Its tensile strength is lower.
• It can be molded easily and has good resistance
  to corrosion.
• It is used to make pipes, corrugated sheets,
  grills, bars, chains and other products.

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• It can be cold worked, forged and welded like
  steel.
• Forging is working a metal to predetermined
  shape by one or more processes such as hammering,
  pressing and rolling at a temperature above the
  re-crystallization temperature.
• Cold working is the process of working at a
  temperature that doesnt alter the structural
  changes caused by the work or that is below the
  re-crystallization temperature.
• Wrought iron is used extensively where corrosion
  resistance is needed.

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• Wrought Iron Gate Wrought Iron Fence

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• Wrought Iron Rack

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CAST IRON

• Manufactured by reheating pig iron (in a cupola)
  and blending it with other material of known
  composition.
• Alternate layers of pig iron (with or without
  scrap steel) and coke are charged into furnace.
• Limestone is added to flux the ash from the
  coke.
• Heat necessary for the smelting is supplied by
  the combustion of coke and air supplied by the
  blast.
• Cupola function to purify iron and produce a
  more uniform product.
• When sufficient metal is accumulated at the
  bottom of the furnace, it is tapped.

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• Composed primarily of iron, carbon and silicon
• Shaped by being cast in a mold
• It has the greatest amount of carbon
• Basically, the amount and form of carbon could
  affect the strength, hardness, brittleness and
  stiffness of cast iron.
• Adding carbon to iron increases its hardness and
  strength but lowers the ductility.
• Cast iron has high compressive strength but its
  tensile strength is low.
• There are 2 types of cast iron that is a) Gray
  Cast Iron b) White Cast Iron

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• Cast Iron Teapot

Cast Iron Pots
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• Cast Iron Bench

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• GRAY CAST IRON
• Gray Cast Iron also known as ordinary ast iron
  owing to the color of fracture.
• It contains free carbon (graphite flakes) that
  makes the metal weak and soft.
• Contains high carbon content and large numbers
  of graphite flakes.
• The flakes gives a gray appearance to a
  fractured surface
• most widely used cast iron
• Have poor ductility

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• Advantages of cast iron are as followsa) Cheap
  b) Low melting pointc) Fluid easy to cast,
  especially advantageous into
  large complex shapes.
• d) Excellent bearing propertiese) Excellent
  damping properties (ability to absorb noise and
  vibration)
• g) Can be heat threatenedh) Can be alloyed

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• White Cast Iron
• White Cast Iron is called in such name due to
  the fracture surface that has a silvery white
  metallic color.
• Carbon is combined chemically with iron in the
  form of cementite that makes this metal strong,
  hard and brittle.
• harder and more resistant to wear from abrasion
  compared to gray iron.
• Excellent wear resistance
• High compressive stress

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• White Cast Iron Daybed

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Steel Products

• Steel alloy consisting mostly of iron with a
  little carbon (0.2 - 2.04 by weight)
• Cast iron carbon content between 2.1 - 4.0
• Iron iron-carbon alloy with less than 0.005
  carbon.
• Wrought iron contains 1 3 by weight of slag
  in the form of particles elongated in one
  direction more rust resistant than steel and
  welds better

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Steel

• Steel is an alloy that consists mostly of iron
  and has a carbon content between 0.2 and 2.1 by
  weight, depending on the grade. Carbon is the
  most common alloying material for iron, but
  various other alloying elements are used, such as
  manganese, chromium, vanadium, and tungsten.
• Steel with increased carbon content can be made
  harder and stronger than iron, but such steel is
  also less ductile than iron.
• Steel is an alloy of iron and carbon. Pure irons
  strength remarkably increases when alloyed with
  carbon. The tensile strength increases with
  increasing carbon content but the ductility
  reduces. Steel having its properties because of
  the presence of carbon alone is called Plain
  carbon steel

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Types of Plain Carbon steel

• Low carbon steel or mild steel
• The carbon content does not increases 0.25
• Soft and ductile
• mostly used for construction purpose
• Uses ? Sheets, rods, wires, pipes, hammers,
  chains, shafts et
• Medium-carbon steel
• The carbon content is 0.25 to 0.5
• Stronger than the mild steel slightly less
  ductile
• Uses ? Shafts, connecting rods and rails etc
• High- carbon steel
• Carbon content is above 0.5
• Harder and stronger than mild steel and medium
  carbon steel
• Uses ? Keys, knifes, drills etc

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The abcs of Steel Making

• Raw Material
• Carbon in the form of coke
• Iron ore (Fe2O3)
• Limestone (CaCO3)
• Air (lots of it!!)

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The abcs of Steel Making

• Coke
• Solid residue product from the destructive
  distillation of coal.
• About 80 to 95 C.
• Made by heating black coal in small ovens at 300
  C for 24 hours in a coke plant.

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The abcs of Steel Making

• The iron ore
• Consists of oxides in nature of iron and oxygen
• Primarily magnetite (Fe3O4) or hematite (Fe2O3)
• The blast furnace basically separates the iron
  from the oxygen in a reduction process
• Mined primarily in Australia, Brazil and Canada.

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The abcs of Steel Making

• The limestone
• Acts as a flux converts impurities in the ore
  into a fuse able slag

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The abcs of Steel Making

• Air
• Preheated by fuel gas from the coke ovens to
  about 1000 C.
• Delivered to the blast furnace at 6,000 m3/min
• Passes through furnace and burns the coke to
  produce heat required and also generates the
  carbon monoxide.

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The abcs of Steel Making

• Typical blast furnace
• 1.6 tons of iron ore
• 0.18 tons of limestone
• 0.6 tons of coke
• 2 -3 tons of preheated air

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The abcs of Steel Making

• Step 1 The Blast Furnace
• Stands 300 feet tall
• Designed to run continuously for 4 -5 years
  before being relined.
• Heat generated by burning coke in the preheated
  air.
• Coke acts as reducing agent and changes to carbon
  monoxide (the reducing agent) which removes the
  oxygen from the iron oxide.

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The abcs of Steel Making

• Step 1 The Blast Furnace
• Four primary zones the bottom zone (zone 4)
  reaches temperature of 1800 C this is where
  iron is tapped off.
• The top zone (zone 1) where coke is burned and
  moisture driven off.
• Zone 2 slag coagulates and is removed.

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The abcs of Steel Making

• Step 1 The Blast Furnace
• Two important chemical reactions
• Oxidation of the carbon from coke

• Reduction of iron ore

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The abcs of Steel Making

• Step 1 The Blast Furnace
• Products from the blast furnace
• Iron stored in steel shelled ladles
• Pig iron (brittle w/ 4 carbon)

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Step 2 Manufacturing of Steel from Iron

• Two common methods
• Bessemer Furnace Ingots molten steel poured
  into molds to create ingots which then go through
  forging press and roughing mill to create billet,
  bloom or slab, OR
• Continuous cast continuous process to again
  create a billet, bloom, slab or as cast semis

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• Step 2 The Bessemer converter
• Used for REFINEMENT
• Takes pig iron with high C content and removes C.
• Removes impurities such as Si and Mn (via oxides)
  
• Much smaller furnace (vs. Blast furnace)
• Lowered cost of steel making
• Poured into molds to form ingots

Replaced by basic oxygen process and electric arc
furnace.
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Steel Ingots
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Heat treatment of Steel

• To develop steel of particular structure or
  conditions best suited for particular work.
• Basis of heat treatment
• At certain temperature called critical
  temperature, all alloys undergo reversible
  constituent change or inversions.
• At heating the critical point differs from that
  in the cooling.
• Holding of material at elevated temperature may
  help it to establish equilibrium of constituents.
• Slow cooling from an elevated temperature above
  critical point permits natural constitutional
  change.
• Rapid cooling or quenching completely inhibits
  the natural change and so tends to retain the
  particular structure.

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Heat Treatment process of steel.

• Hardening process
• The degree of hardness of steel depends on
  proportions of these three forms
• For steel containing less than 0.85 carbon, the
  hardening temperature must be above 885C0 to
  ensure that ferrite is dissolved.
• In case of steel having more than 0.85 of
  Carbon, comentite itself is very hard and needs
  temperature slightly above 730C0
• For steel with very low carbon, to harden the
  steel.
• Quenching
• Rapid Cooling
• Tampering
• When a piece of steel is hardened by heating
  above the critical range and then quenched, it is
  too hard for practical purpose.
• Drawing
• At comparatively higher temperature and below
  critical temp, the steel is drawn and cooled
  softens steel.
• Annealing
• Heating above the critical Temp, and then very
  slowly cooling it making it more ductile and
  tough.
• Normalizing
• Steel is heated above the critical Temp but
  cooled rapidly, which refines the grains of the
  steel.

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Steel Products

• Steel is marketed in a wide variety of sizes and
  shapes, such as rods, pipes, railroad rails,
  tees, channels, and I-beams.
• These shapes are produced at steel mills by
  rolling and otherwise forming heated ingots to
  the required shape. The working of steel also
  improves the quality of the steel by refining its
  crystalline structure and making the metal
  tougher.
• The basic process of working steel is known as
  hot rolling. In hot rolling the cast ingot is
  first heated to bright-red heat in a furnace
  called a soaking pit and is then passed between a
  series of pairs of metal rollers that squeeze it
  to the desired size and shape. The distance
  between the rollers diminishes for each
  successive pair as the steel is elongated and
  reduced in thickness.

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• The first pair of rollers through which the ingot
  passes is commonly called the blooming mill, and
  the square billets of steel that the ingot
  produces are known as blooms. From the blooming
  mill, the steel is passed on to roughing mills
  and finally to finishing mills that reduce it to
  the correct cross section. The rollers of mills
  used to produce railroad rails and such
  structural shapes as I-beams, H-beams, and angles
  are grooved to give the required shape.
• Modern manufacturing requires a large amount of
  thin sheet steel. Continuous mills roll steel
  strips and sheets in widths of up to 2.4 m (8
  ft). Such mills process thin sheet steel so
  rapidly, before it cools and becomes unworkable.
  A slab of hot steel over 11 cm (about 4.5 in)
  thick is fed through a series of rollers which
  reduce it progressively in thickness to 0.127 cm
  (0.05 inc) and increase its length from 4 m (13
  ft) to 370 m (1210 ft).

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Continuous mills are equipped with a number of
accessory devices including edging rollers,
de-scaling devices, and devices for coiling the
sheet automatically when it reaches the end of
the mill. The edging rollers are sets of
vertical rolls set opposite each other at either
side of the sheet to ensure that the width of the
sheet is maintained. De-scaling apparatus removes
the scale that forms on the surface of the sheet
by knocking it off mechanically, loosening it by
means of an air blast, or bending the sheet
sharply at some point in its travel. The
completed coils of sheet are dropped on a
conveyor and carried away to be annealed and cut
into individual sheets.
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A more efficient way to produce thin sheet steel
is to feed thinner slabs through the rollers.
Using conventional casting methods, ingots must
still be passed through a blooming mill in order
to produce slabs thin enough to enter a
continuous mill. By devising a continuous
casting system that produces an endless steel
slab less than 5 cm (2 in) thick, German
engineers have eliminated any need for blooming
and roughing mills. In 1989, a steel mill in
Indiana became the first outside Europe to adopt
this new system.
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Pipe Cheaper grades of pipe are shaped by
bending a flat strip, or skelp, of hot steel into
cylindrical form and welding the edges to
complete the pipe. For the smaller sizes of pipe,
the edges of the skelp are usually overlapped and
passed between a pair of rollers curved to
correspond with the outside diameter of the pipe.
The pressure on the rollers is great enough to
weld the edges together. Seamless pipe or tubing
is made from solid rods by passing them between a
pair of inclined rollers that have a pointed
metal bar, or mandrel, set between them in such a
way that it pierces the rods and forms the inside
diameter of the pipe at the same time that the
rollers are forming the outside diameter.
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Tin Plate By far the most important coated
product of the steel mill is tin plate for the
manufacture of containers. The tin can is
actually more than 99 percent steel. In some
mills steel sheets that have been hot-rolled and
then cold-rolled are coated by passing them
through a bath of molten tin. The most common
method of coating is by the electrolytic process.
Sheet steel is slowly unrolled from its coil and
passed through a chemical solution. Meanwhile, a
current of electricity is passing through a piece
of pure tin into the same solution, causing the
tin to dissolve slowly and to be deposited on the
steel. In electrolytic processing, less than half
a kilogram of tin will coat more than 18.6 sq m
(more than 200 sq ft) of steel.
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For the product known as thin tin, sheet and
strip are given a second cold rolling before
being coated with tin, a treatment that makes the
steel plate extra tough as well as extra thin.
Cans made of thin tin are about as strong as
ordinary tin cans, yet they contain less steel,
with a resultant saving in weight and cost.
Lightweight packaging containers are also being
made of tin-plated steel foil that has been
laminated to paper or cardboard. Other processes
of steel fabrication include forging, founding,
and drawing the steel through dies.
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Figure 9-12 processing of refined steel into
products.
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F 9-13 The whole spectrum of steel products!
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Classifications of Steel Steels are grouped into
five main classifications. Carbon Steels More
than 90 percent of all steels are carbon steels.
They contain varying amounts of carbon and not
more than 1.65 percent manganese, 0.60 percent
silicon, and 0.60 percent copper. Machines,
automobile bodies, most structural steel for
buildings, ship hulls, bedsprings, and bobby pins
are among the products made of carbon steels.
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Classifications of Steel Steels are grouped into
five main classifications. Carbon Steels More
than 90 percent of all steels are carbon steels.
They contain varying amounts of carbon and not
more than 1.65 percent manganese, 0.60 percent
silicon, and 0.60 percent copper. Machines,
automobile bodies, most structural steel for
buildings, ship hulls, bedsprings, and bobby pins
are among the products made of carbon steels.
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Alloy Steels These steels have a specified
composition, containing certain percentages of
vanadium, molybdenum, or other elements, as well
as larger amounts of manganese, silicon, and
copper than do the regular carbon steels.
Automobile gears and axles, roller skates, and
carving knives are some of the many things that
are made of alloy steels.
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High-Strength Low-Alloy Steels Called HSLA
steels, they are the newest of the five chief
families of steels. They cost less than the
regular alloy steels because they contain only
small amounts of the expensive alloying elements.
They have been specially processed, however, to
have much more strength than carbon steels of the
same weight. For example, freight cars made of
HSLA steels can carry larger loads because their
walls are thinner than would be necessary with
carbon steel of equal strength also, because an
HSLA freight car is lighter in weight than the
ordinary car, it is less of a load for the
locomotive to pull. Numerous buildings are now
being constructed with frameworks of HSLA steels.
Girders can be made thinner without sacrificing
their strength, and additional space is left for
offices and apartments.
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Stainless Steels Stainless steels contain
chromium, nickel, and other alloying elements
that keep them bright and rust resistant in spite
of moisture or the action of corrosive acids and
gases. Some stainless steels are very hard some
have unusual strength and will retain that
strength for long periods at extremely high and
low temperatures. Because of their shining
surfaces architects often use them for decorative
purposes. Stainless steels are used for the pipes
and tanks of petroleum refineries and chemical
plants, for jet planes, and for space capsules.
Surgical instruments and equipment are made from
these steels, and they are also used to patch or
replace broken bones because the steels can
withstand the action of body fluids. In kitchens
and in plants where food is prepared, handling
equipment is often made of stainless steel
because it does not taint the food and can be
easily cleaned.
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Tool Steels These steels are fabricated into
many types of tools or into the cutting and
shaping parts of power-driven machinery for
various manufacturing operations. They contain
tungsten, molybdenum, and other alloying elements
that give them extra strength, hardness, and
resistance to wear.
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Alloys of Steel

• Most of the steel used in the buildings
  Engineering is purposefully alloyed with one or
  more elements to modify its properties.
• By the terms alloying, it is understood that some
  other element other than carbon is added to iron.
  The ordinary steel containing carbon is termed as
  alloy of Carbon and Iron.
• Usually metals like nickel, chromium, manganese,
  vanadium, are added to steel for making alloys.

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• Nickel steel
• The amount of nickel varies from 1 to 4.5 and
  Carbons varies from 0.1 to 0.4.
• Nickel improves the tensile strength and reduces
  brittleness and imparts hardness and ductility to
  steel.
• Rust formation is resisted with higher content of
  nickel.
• Nickel steel having 3 to 4.5 nickel is
  frequently used for long span bridge
  construction, shafting, rifle barrels, bearings,
  castings.
• Steel alloys having 36 nickel and 0.5 carbon
  is called Invar which is used for measuring tapes
  and pendulum of clocks, where change in
  dimensions is minimum.
• Steel alloy with 46 nickel and very little
  carbon is known as Platinite, which has same
  thermal coefficient as glass.

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• Chrome Steel
• 0.5 to 2 Chromium, 0.2 to 1.5 carbon are used
  for parts where great hardness, high strength and
  fair degree of toughness is required.
• Steel with 0.5 chromium and 0.6 to 0.9 carbon
  are generally used for manufacturing of chisels,
  drills, razors and saw blades.
• Tungsten Steel
• Oldest of steel alloys, used for permanent
  magnets.
• With 3 Tungsten, it becomes suitable for lath
  tools.
• With about 1 carbon, it produces good steel for
  use in springs.
• Tungsten forms essential part of high speed
  tools.

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• Molybdenum steel
• MB used in small quantity 0.3 in combination
  with Chromium and Manganese, makes high tensile
  steel suitable for automobile parts.
• Silicon steel
• Used for Transformer cores and dynamos.
• High Speed Steel
• It may run at red heat without losing its
  hardness
• 15-20Tungsten, 3-5 Cr, 0.5-2 Vanadium,0.6-0.8
  Carbon with silicon, sulphur, and phosphorous.
• Used in parts which withstands high heat and
  wear as required for exhaust valves.