basic metallurgy -iron carbon diagram-21mar12

8/11/2019 Basic Metallurgy -Iron Carbon Diagram-21mar12

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Metals are the backbone of the

engineering industry being the mostimportant Engineering materials.

In comparison to other engineeringmaterials such as wood, ceramics, fabricand plastics, metals are used in:

Large tonnage

Offers very wide range of properties

Highest possible strength

Engineers main concern:

mechanical properties of the metal,

however,

ompos ons

Shaping history

Heat treatment

Have tremendous effect on the behavior ofthe material.

Mechanical strength

Ductility & toughness

Hardness

Fatigue strength

Corrosion resistance

Wear resistance

Creep resistance

Resistance to heat and oxidationdamage

Resistance to radiation damage

Extractive Metallurgy

> deals with processing of the natural occurringraw materials converting in to useful metalsand alloys.

Adaptive Metallurgy (Physical Metallurgy)

> which deals with identifying, controlling andvarying the properties of the metals and

alloys as per requirement of the mankind.


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Ferrite % carbon up to 0.006%

Phase solid ferrite

Pearlite when carbon content reaches.

Phase solid Pearlite or (ferrite + cementite)

Cementite when carbon content increasedup to 1.7%.

Phase solid Pearlite + cementite

Austenite

> is the structure above the eutectoidpoint or the phase above the critical

temperature of 723 deg C ( 1333 deg F)Phase solid

Mo st hea t treatm ent p roce ss shou ld rea c h f irst

the a usteni t ic structure (hom og eno us) pr ior to

co o l ing to rea ch the d esi red m ate ria l

propert ies.

-Improve the toughness

- Improve the machinability

- Increase the hardness

- Refine the grain structure

- ili- ili

-Remove the residual stresses

- Improve the wear resistance

Pearlite

Bainite

Martensite

Pearlite structure produced when austenite is cooled in very slow

rates.

Bainite is a result when austenite is cooled at a rate

(controlled temperature) lower than what is neededto form martensite.


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Martensite a microstructure produced after quenching

Quenching

- The p roc ess of c oo ling a usten ite ve ry

ra id l o r a t a c on tro lle d ra t e t o a c h ie v e

a d esired mic rostruc ture.

* The rapid cooling suppresses theformation of austenite to + Fe3C

Use/applications - materials that demand ahard material (e.g. knives, razor blades,surgery tools, cutting tools, etc).

The addition of carbon tosteel causes the material tofreeze over a temperaturerange and form anotherstructure with improveproperties.

Carbon has the effect ofincreasing hardness andstrength by heat treatment.

This is the main reason why

carbon steel is widely used inthe engineering industry

No one is knowled g ea b le

eno ug h to know eve ry th ing

So ta ke t im e to rea d a nd lea rn

.

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basic metallurgy -iron carbon diagram-21mar12

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