Iron Iron constitutes about4.60 parts of the crust of earth It is also contained in the leaves plant It is basically responsible for the red color in the.

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Iron

• Iron constitutes about4.60 parts of the crust of earth • It is also contained in the leaves plant • It is basically responsible for the red color in the blood

of animals • Iron ores are present in the following forms • Hematite –Fe2O3• Limnonite-2Fe2 O3.3H2O• Magnetite-Fe3 O4• Pyrite FeS2• Siderite-FeCO3

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• Haematite: red oxide of iron. Rich in iron ore.colour is iron black or steel gray.ore is available in Mysore and Madhya Pradesh.

• Magnetite : black oxide of iron. It is richest iron ore. it is black in colour. It is available in Chennai.

• Limonite: brown haematite. Colour brown, yellowish brown, or yellow. Available in Jamshedpur.

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• Iron pyrite: sulphide of iron. Colour is bronze yellow or pale brass yellow. This ore is widely spread almost all parts of the world. Brittle ore. So it is not adopted in the manufacture of iron.

• Siderite: It is carbonate of iron. Colour is pale yellow, brownish red or brownish black . Ore available in Bengal

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Selection of iron ore

• The iron ores are taken out or extracted from earth by mining operations .

• The iron ore available from mines should be rich in metallic iron content.

• The mines for iron ores should be located at such a place that they are easily accessible and should be linked with surrounding town by suitable transport facilities.

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• The composition of substance associated with ore should be carefully studied.

• The treatment and preparation given to iron ore to make them suitable for blast furnace should be simple and cheap.

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.PIG IRON--The crude impure Iron extracted from Iron-Basic Material for manufacturing of Cast Iron, Wrought Iron and Steel.Pig iron is the intermediate product of smelting iron ore with a high-

carbon fuel such as coke, usually with limestone as a flux. It is the molten iron from the blast furnace, which is a large and cylinder-shaped furnace charged with iron ore, coke, and limestone.

Charcoal and anthracite have also been used as fuel. Pig iron has a very high carbon content, typically 3.5–4.5%, which makes it very brittle and not useful directly as a material except for limited applications

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Properties• Hard and Brittle with fusion temp of 1200degC

and melt easily.• Can be hardened but cannot be tempered and

manufactured.• Compressive strength is high but weak in

tension and shear.• Does not rust but cannot be riveted or welded.

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MANUFACTURING OF PIG IRON

Dressing

Calcination and roasting

Smelting

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• Dressing : iron ore obtained from mines are crushed to pieces of size 25 mm.During crushing ,the ore particles of uniform size are obtained.

• Calcination and roasting : Heating ore in presence of air so that they are oxidized. The water and carbon dioxide are removed from ores by calcination.The roasting consist of making the ores hot and very dry.

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• Smelting : the melting so as to separate metal from ore. Carried out in special type of furnace ,known as blast furnace. It is in the form of a vertical steel cylinder.

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Cast iron

• It is manufactured by remelting pig iron with coke and lime stone.

• Remelting is done in furnace.• The impurities of pig iron is taken out in the

molten stage from the bottom of the furnace.

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Properties of cast iron

• Specific gravity is 7.5• It can be hardened by heating and sudden cooling,

but cannot be tempered.• It cannot be magnetized• It does not rust easily• If placed in water it becomes soft• It is hard and brittle• It is not ductile• It shrinks on cooling

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• It is not plastic, hence not suitable for forging• It is weak in tension and shear but strong in

compression• Two cast iron pieces can not be connected by

process of riveting or welding• It is affected by sea water.

Uses of cast iron

• Making water pipes, gas pipes, sewers manhole covers and sanitary fittings.

• Ornamental castings such as gates lamp posts spiral stair case

• For making parts of machinery which are not subjected to heavy shocks

• For making compression members like column, bases of column

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Effect of impurities

• Carbon : cast iron contains 2 to 4 % of carbon.• Manganese : makes cast iron brittle and hard.• Phosphorus: increases fluidity of cast iron • Sulphur: causes rapid solidification of cast iron it make it brittle and hard.• Silicon : reduces the solubility of carbon in

iron and shrinkage

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Wrought iron

• Most pure iron and produced by removing impurities of cast iron

• Total impurities are limited to .5 percentage with maximum percentage of carbon as .15 percent

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Manufacture of wrought iron• Reverberatory furnace by Astor’s processPROPERTIES OF WROUGHT IRON

It is ductile ,malleable and moderately elastic

Can be used to form temporary magnets ,but cannot be

magnetized permanently

Unaffected by saline water

Resist corrosion in a better way

Ultimate crushing strength is 200 N/mm^2

Ultimate tensile strength is 40 N/mm^2

Specific gravity is about 7.8

Tough and withstand shocks

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Uses of wrought iron

• Used where tough material is required.• Used for roof

covering ,rivets,chains,ornamental works railway couplings water and steam pipes

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STEEL

• Most popular and effective building material• Alloy of iron and carbon • The steel becomes harder and tougher as its

carbon goes on increasing and at the maximum level of 1.5%

• Suitable for construction purpose • It replaces cast iron and wrought iron• Equally strong in compression and tension

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Carbon content- carbon increases strength but decrease ductilityPresence of impurities –impurities affect the quality of steelHeat treatment processes –varies depending upon the type of treatment

STEEL

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Mild Steel is general purpose steel grade, basically used for

alloying and manufacturing of fabrication of various

structures.

The Steel generally made of low Carbon and Silicon.

The yield strength values are very low for Mild Steel, as the

name suggest.

Therefore it is not used for special purpose of reinforcing and

heavy structure manufacturing.

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• Where as, HYSD is High Yield Strength Deformed Bars have ribs on

the surface and this increases the bond strength at least by40%.

These are made of different grades and types.

• Mild steel contains low Carbon content whereas HYSD is High

Yield Strength Deformed bars contains more carbon content.

Mild steel strength is low but ductile (easy to shape) and more

weldable.

HYSD is used where tensile strength requirements are high.

HYSD is more brittle depending on the carbon content

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• Where as, HYSD is High Yield Strength Deformed Bars have ribs on the

surface and this increases the bond strength at least by40%.

These are made of different grades and types.

• Mild steel contains low Carbon content whereas HYSD is High Yield

Strength Deformed bars contains more carbon content.

Mild steel strength is low but ductile (easy to shape) and more weldable.

HYSD is used where tensile strength requirements are high.

HYSD is more brittle depending on the carbon content

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STRUCTURAL STEEL SECTIONS

Angle sectionsChannel sectionsCorrugated sheets Expanded metal T-sections I-sections Plates

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Angle sections

• May be of equal leg or unequal leg• Equal leg sections are available in varying

sizes from size 20mm* m20mm*3mm to 200mm*200m m*25mm and corresponding weifgt 9N to 736N

• Unequal angle sections are available from 30 mm*20mm*3mm to 200mm *150mm *18mm

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Angle sections

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Channel sections

• Available in sections 100mm*45mm to 400mm*100mm

• Bureau of indian standard has classified the channel a junior channel ,light channel ,Medium channel

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Channel section

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Corrugated sheets

• Generally galvanized they are named accordingly

• Widely used for roof covering

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Corrugated sheets

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Expanded metal

• This form of steel is available in different shapes and sizes• Used for reinforcing foundations• diamond mesh like appearance is formed

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T-Sections

• The shape of the section is that of the letter T• It is designated by overall dimension and thickness • Available varying from in sizes from

20mm*20mm*3mm to 150mm*150mm*10• Mainly used as members as steel roof truss and to

form built up sections

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T-section

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I-Sections

• Known as rolled steel joist or beams • Consist of two flanges connected by a web• Designated by overall depth , width of flange and weight per

meter length• Available in various sizes 75mm*50mm at 61N to

600mm*210mm at 995N• Thy are mainly used for beams and columns • Bureau of indian standard classify Isections in to Junior

beams ,light beams ,medium beams ,wideflange beams and heavy beams and they are accordingly designated as I.S.J.B,I.S.L.B,I.S.W.B,I.S.H.B.

• Used for floor beams lintels and columns

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Plates

• Plate sections are available in thickness varying from 5mm to 50mm with the corresponding weight of 392N and 3925N

• They are mainly used for connecting steel beams for extension of length , to form as a tension member of steel roof truss, to form built up sections of steel

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Plates

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Reinforcing steel

• The various types of reinforcement bars are as follows• Ribbed (HYSD ) bars • Round bars • Square bars • Flat bars • Ribbed mild steel bars• Thermo mechanically treated bars • Cold twisted deformed bars • Welded wire fabrics (WWF)

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Ribbed (HYSD ) bars

• high yield strength Deformed steel having ribs or projections in their surface

• They are produced by controlled cold twisting of hot rolled bars

• Available in sizes varying6mm to 50mm with corresponding weight 2.22Nand 154.10N

• They are used as reinforcement for all type of concrete work

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Round bars

• Available in circular cross- sections varying from 5mm to 250mm

• Used as reinforcement in concrete structures , steel grill work

• Commonly used are 5mm to 25mm dia weight 1.5N and 38N

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Square bars

• Square bars • They are available in square section from

5mm to 250mm• Used in construction of steel grill work, for

windows • General cross section vary from 5mm to

25mm

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Square bars

• Square bars • They are available in square section from

5mm to 250mm• Used in construction of steel grill work, for

windows • General cross section vary from 5mm to

25mm

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Square bars

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Flat bars

• available in suitable widths varying from 10mm to 400mm

• Generally available are 3mm to 40mm

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