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Anonymous Poster

mechanical

11/10/2008 4:54 AM

in iron phase diagram ,why ferrite is placed below 723 temp. & austinite is placed above 723 temp.

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#1

Re: mechanical

11/10/2008 5:10 AM

Hello Guest,

Because that's how it is. (apart from your spelling error of martensite)

Please refer to the excellent explanation and diagrams right here: http://www.roymech.co.uk/Useful_Tables/Matter/Phase_diagram.html

Please get used to using Internet Search Engines, which will save you much of your irreplaceable lifespan, by enabling you to find wanted information very quickly.

Kind Regards....

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#2
In reply to #1

Re: mechanical

11/10/2008 5:23 AM

austenite?

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#5
In reply to #2

Re: mechanical

11/10/2008 6:36 AM

Hello JohnDG

from me

You caught me out, in the mistake I made, and thank you for your correction of austinite to austenite.

Enjoy a GA point because of your careful reading.

Kind Regards....

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#3

Re: mechanical

11/10/2008 5:57 AM

If you take a book about the diagram you find ALL answers to the 3 questions. You could as well use wikipedia or other sources you get via GOOGLE.

It is better to use the skills of CR4 when the explanations are not clear or when your questions ask for more detailed answers. As your questions are you are at the "start" and all sources in the net will give all what you need.

Try first to make an effort before you ask for pre-chewed input.

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#4

Re: mechanical

11/10/2008 5:57 AM

That's it. Iron itself appears as an allotropic element that changes structure according temperature, due to the internal energy associated with temperature.

It's CCC up to 723 (called ferrite-alfa), CFC on, and CCC again up to around 1100 deg (typ) (called ferrite-delta). When quickly cooled from austenite region to ferrite, there's no time enough to carbon to diffuse in the iron matrix, and it gets traped in the structure deforming it to a tetragonal shaped structure, what's called martensite.

Do you have any specific doubt about it?

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