Building materials by Sourav Zaman, Lecturer Department of Architecture Northern University of Business and Technology

1. COURSE NO: ARCH 1201
COURSE TITLE: BUILDING MATERIALS
Lecture 8
IRON & STEEL

2. IRON & STEEL

3. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Iron is still the most widely used engineering material in the world.
Strength and weight ratio
Iron Ores
Pig Iron
IRON
Ferrous Metals- Iron / Steel

4. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Iron Ores
Compounds of Iron usually oxides mixed with
aluminum, silica, clay, etc.
Contain 25-75% metallic iron
Chief Iron ores from which pig iron is
extracted:
1. Hematite
2. Limonite
3. Magnetite
4. Siderite
5. Iron Pyrites
IRON

5. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Iron Ores
1. Hematite
 Red ferric oxide (F2O3) and contains 70%
iron
 Because of earthy matter & other
impurities yield about 55-60% iron only.
2. Limonite
 Brown hematite (2F2O3. 3H2O) and is a
hydrated ferric oxide
 Contain 60% of iron but reduced to about
45% due to impurities
IRON
Hematite
Limonite

6. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Iron Ores
3. Magnetite
 Black oxide of iron (Fe2O3 )
 Contain 73% of iron & less impurities
 Richest & hardest iron ore
4. Siderite
 Gray or brown carbonate of iron (Fe2CO3 )
 Contain 40% of iron
5. Iron Pyrites
 Yellow sulphide of iron ((FeS2 )
 Contain 45% of iron
 Not considered to be a good ore because
of its high sulphuric contents
IRON
Iron Pyrites
Siderite
Magnetite

7. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Pig Iron
Heating & melting of iron ores
IRON
Blast furnace
3000º F
2 process take place in the
blast furnace
Di-oxidation of iron ores
(Reduction)
Separation of iron ores from impurities
like clay, sand etc
(Gangue)

8. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Pig Iron
Gangue
IRON
Common impurities in the iron ores
Silica & Alumina
Iron ores + Lime stone (CaCO3) Blast Furnace
(Coke or charcoal)
Remove
Silicates & Aluminates of calcium 2000° F
Slag

9. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Composition of pig iron
Iron 92-94%
Carbon 4-5%
Silicon 1-2%
Manganese 1-2%
Sulphar & Phosphorus 1-2%
IRON
Uses of slag
 Making of blast furnace cement
 Railway ballast
 Road metals
 Coarse aggregates for concrete
 Fertilizer as contains sulphates and
phosphates.
Composition of slag
Lime 40-45%
Silica 30-35%
Alumina 10-12%
Magnesia, calcium, 6-8%
Sulphate,
Manganese oxide etc

10. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Classification of pig iron
Based on carbon content either free or combined
1. Gray pig iron
 Contain 3-4% of free carbon & less than 1% combined
carbon
 Soft variety of pig iron containing bigger size crystals
 Suitable for foundry casting
 Cast iron is manufactured from this pig iron
2. White pig iron
 Contain 3% of combined carbon & less than 1% free
carbon
 Containing close grained crystals
 Very hard & strong & could be easily melted
 wrought iron is manufactured from this pig iron
IRON
Gray pig iron
White pig iron

11. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Classification of pig iron
3. Mottled pig iron
 Contain equal amounts of free carbon & combined carbon
 Mottled appearance & medium hardness
 Malleable cast iron is manufactured from this pig iron
Pig iron is also classified according to the presence of phosphorus
1. High phosphorus pig iron (0.5-0.7%) of phosphorus
2. Low phosphorus pig iron (0.3-0.5%) of phosphorus
IRON

12. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Wrought Iron Cast Iron
Two forms of Iron
IRON

13. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Wrought iron
IRON
Obtained by smelting white pig iron in a pudding
furnace
Wrought iron is a soft, ductile, fibrous variety that
is produced from a semi fused mass of
It usually contains less than 0.1 percent carbon
and 1 or 2 percent slag.
 It is superior for most purposes to cast iron.
Properties
Pasty & very plastic at red heat
Could be easily forged about 1650° F & it melts about
2800° F
Very malleable & ductile
Good resistance to fatigue (repeated stress) & corrosion
Weldability

14. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Uses of Wrought iron
IRON
Standard pipes, bars, rods, wires, plates , sheets, welding
fittings, rivets etc.
Wrought iron products used in building construction, bridge
construction, railroad, marine & chemical industries
 corrugated sheet (C.I Sheets) & ornamental works.

15. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Cast iron
 Hard, relatively brittle alloy of iron and
carbon
 Contains a higher proportion of
carbon
IRON
Properties
 Strong in compression but weak in tension
 Brittle does not absorb shocks
 Does not posses the properties of ductility & malleability
 Gray cast iron is softer then white cast iron
 Very low cost of production & can be cast to any convenient shape

16. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Uses of Cast iron
IRON
 For making C.I pipes (used for water mains & sewers)
 Covers (manhole covers etc)
 Columns with their caps & bases, struts, carriage wheels,
parts of machinery
 Gates, railings, window frame, gratings & other
ornamental works

17. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Steel is an alloy of iron
Carbon containing less than 2% carbon
There are grades of steel :
1. Soft, mild or low carbon steel .05- .15% carbon
2. Medium carbon steel or medium hard steel .15- .30% carbon
3. Medium high carbon steel or half-hard steel .30-.60% carbon
4. High carbon steel or hard steel .60-1.5% carbon
STEE
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18. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Properties of steel
•Great strength though it is light in weight
Compressive
Tensile
Flexural
Shear
•Cool down rapidly from an extremely hot temperature after being
subjected to water or oil
•Ductility means steel can be molded easily to form any desired shape.
•Dimensional stability of steel is a desired property
•Good conductor of electricity
•The higher the carbon content, the harder and stronger is the steel metal.
•A high quality steel containing less carbon is more ductile.
• Galvanized steel is coated with zinc to protect it from corrosion,
whereas stainless steel contains about 10 percent chromium in its
composition.
STEE
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19. A Text Book of Engineering Materials- by Dr. M. A. Aziz
Stainless Steel
with a minimum of 10.5% Chromium
Passive layer
 Stainless steel to resist corrosion, heat
damage and chemical damage
 High strength duplex grades provide
added strength
 High and low temperature resistance
 Aesthetic appeal
 Hygienic properties
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20. RECOMENDED REFERENCES
Aziz. M. A: Engineering Materials.
Smith, R. C: Material of construction.
Andres, C. K: Manufactures manuals and brochures,