The Time Value of Money

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Metals-Ferrous and Non Ferrous
By Engr. 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

• 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.

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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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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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Figure 9-12 processing of refined steel into
products.
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F 9-13 The whole spectrum of steel products!