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Babaria Institute of TechnologyTopic name: - Study of Plain Carbon Steel

Subject: - Material Science & Metallurgy

Prepared By: - Hardik Sakpal (150050119096)

Branch: - Mechanical

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The Primary Constituents of Plain Carbon Steel are Iron &

Carbon.

Plain carbon steel is a type of steel having a maximum

carbon content of 1.5% along with small percentages of

silica, sulphur, phosphorus and manganese.

They can be used successfully only if the application does

not have more strength & other engineering applications.

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Classification of Plain Carbon Steel

Low Carbon Steel

Medium Carbon Steel

High Carbon Steel

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Low carbon steel Containing carbon up to 0.25% responds to heat treatment as improvement

in the ductility is concerned but has no effect in respect of its strength

properties.

They are not improved in terms of strength & hardness properties by heat

due to lack of carbon.

The microstructure of low carbon steels consists of more amounts of ferrite

& less amount of pearlite.

They are relatively soft & weak but have extraordinary ductility &

toughness.

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Microstructure of low of Carbon steel

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Applications

Low Carbon steels are suitable for automobile & refrigerator

bodies, cans, corrugated sheets , structural shapes, etc.

Their applications also include nails, nut, bolts, boiler-plates,

ship-plates, reinforcing bars, pipelines, etc.

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Steel nuts

Fence

Steel wires

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Medium carbon Steels:

Medium carbon steels contain 0.3% to 0.6% carbon.

They exhibit a better response to heat treatment compared to low

carbon steels.

Their Mechanical properties can be improved by hardening

followed by tempering heat – treatments.

By adding alloying, their ability to get hardened can be increased.

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Microstructure of Medium Carbon Steel

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Application

Some typical applications of medium carbon steel include

gears, axels, levers, cams, bolts, sockets, screw drivers, auger

bits, cylinder liners, cylinders, hand tools, rims of bicycle &

automobile-wheels, railway car- wheels & tracks, railways

couplings, rifle barrels, balls of ball mill & machine

components.

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Balls of Ball Mill

Axle

Rims of bicycle

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High Carbon Steels High carbon steels contain carbon from 0.6% to 2%.

They are hardest and strongest among plain carbon steels but least ductile.

They have poor formability, machinability & weldability as compared to

medium carbon steel; but good hardenability.

The alloying elements such as tungsten, molybdenum, chromium &

vanadium can be added in these steels to form hard & wear resistant

carbide compounds. Such high carbon steels with carbide compounds can

be used for making tools & dies.

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Microstructure of High Carbon Steel

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Application

The typical applications of high carbon steels include

lock washers, valve springs, wrenches, cutting tools,

dies, shearing knives, anvils, chisels, hammers, milling

cutters, tapes, razors, hacksaw blades, piston rings &

gauges.

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Lock Washers

Valve Springs

Wrenches

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Effect of impurity elements on properties of plain carbon

steels There are four common impurity elements in plain carbon

steels a. Silicon b. Manganese c. Sulphur d. Phosphorus. The properties of plain carbon steels primarily depend upon the

carbon content & to a large extent upon these four impurity elements.

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Silicon

Its content in plain carbon steel varies from 0.05% to 0.30% .

It is a good strengthened of ferrite in steels.

It increases strength, hardness & toughness without loss of

ductility.

It is strong deoxidizer and removes dissolved gases & oxidizes

during solidification of steel.

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Manganese The manganese content in plain carbon steel varies from 0.3% to 1.0%.

It decreases the harmful effect of sulphur, i.e. brittleness at high

temperature by forming MnS thereby reducing content of FeS.

It increases the hardenability of the steel.

It dissolves in ferrite 7 increases yield strength, tensile strength,

toughness & ductility considerably.

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Sulphur

Normally, sulphur content in the steel should be allowed to exceed

0.05%.

The inclusions of FeS soften & may melt at rolling or forging

temperatures reducing the tenacity of the hot metal & sometimes causing

disintegration by cracking in the rolls or under the hammer.

This is called as hot shortness or hot embrittlement.

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Phosphorus

The maximum content of phosphorus does not exceed 0.04%.

Phosphorus dissolves in ferrite, increasing strength, hardness &

improving the resistance to corrosion. So, it is added to low

carbon steels up to 0.12%.

It is added to improve machinability of certain grades of free

cutting steels up to a maximum content of 0.12%.

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Limitations of Plain Carbon SteelI. The strength of plain carbon steels cannot be increased beyond 700 Mpa

without substantial loss in ductility & impact strength.

II. They have poor impact strength at low temperatures.

III. They have poor corrosion resistance & oxidation resistance.

IV. Properties do not remain uniform for larger thickness of plain carbon

steels.

V. They are not deep hardenable.

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