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STUDY OF MICROSTRUCTURE STUDY OF MICROSTRUCTURE

STUDY OF MICROSTRUCTURE - PowerPoint Presentation

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STUDY OF MICROSTRUCTURE - PPT Presentation

PURE IRON 02 04 08 12 CARBON STEELS WHITE GRAY MALLEABLE AND NODULAR CAST IRON HARDENED STEELS We have to study microstructure of the following Pure iron ID: 625377

carbon iron cast cementite iron carbon cementite cast steels pearlite ferrite hard white steel graphite tough strength ductile alfa

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Slide1

STUDY OF MICROSTRUCTURE

PURE IRON, 0.2, 0.4, 0.8, 1.2 CARBON STEELS. WHITE, GRAY, MALLEABLE AND NODULAR CAST IRON. HARDENED STEELS

We have to study microstructure of the following ……Slide2

Pure iron

Grains of ferrite Grain boundries

Eutectoid steel

0.8 % carbon

Alternate plates of

alfa

ferrite and

cementite

i.e

pearlite

Soft, ductile, mild having low strength.

Can not harden by heat treatments Shows allotropic changes. Bcc, fcc bcc tec.

Hard and tough, having high strength

Harden by heat treatment.Slide3

Pearlite

i.e. alternate plates of alfa ferrite 88% and cementite 12%

Ferrite

collected at

boundries

0.2 and 0.4 %c steels

are

hypoeutectoid

steels

Show

pearlite + alfa ferrite in structure1.2 % c steels is a hypereutectoid steel Shows pearlite + cementite

in microstructure

pearlite

Cementite

collected at

boundries

Slide4

Gray cast iron

Carbon is in the form of graphite flakes, resulting structure is soft and ductile in comparison with white cast iron Graphite flakes

White portion of the structure is of

cementite

,

Very hard and brittle.

Wear resistant and has high compressive strength.

cementite

White cast iron

App– machine bases, engine frames, drainage pipe, fly wheels, pump housings etc.

App– excavator bucket teeth, wearing plates, concrete mixers, road rollers, mill liners, grinding balls, dies and extrusion nozzles etc.Slide5

Carbon

is accumulatedCalled as bulls eye structureHardness is reduced

Malleable

cast iron

Nodules or globules of carbon

Ductile

iron, nodular

ci

,

Or

spheroidal

graphite

cast iron

Carbon is converted in the form of nodulesSoft and ductileLow hardness

App– paper industries machineries, internal combustion engines,

power transmission equipments,

valve and fittings,

pumps and compressor parts.

App--Used for thin walled and small components, hinges, door

kies

, spanners, crank, levers, parts of sewing and textile machines.Slide6

Hardened steel

Needles of martensite

Resulting steel is very hard and tough.

Transformed by

martempering

process or by conventional quenching. Followed by tempering to relieve internal stresses.

martensite

bainite

Transformed by

austempering

process i.e. by isothermal cooling , bath is maintained at nose temp. of TTT diagram.

Hard and tough

No need of tempering.Slide7

Thanks !!!