[MW:12295] RE: 12289] Uncontrolled heating and cooling effect of Carbon steel below lower critical temperature

Limesh –

 

Your range of C is such that you can have a broad range of starting microstructures. 

So in answer to Query 1 – Yes depending on starting microstructure, heating may cause significant changes for which the rate would be unimportant.  “Uncontrolled” Rapid heating for the hypereuctectic compositions and cast irons will probably result in cracking. 

Query 2- Assuming you heated from room temperature ( or there about) PRIOR TO cooling,  as long as you are below the lower critical temperature there will be no change due to cooling rate.  Again, you will more than likely crack hypereutectic steels and cast irons.

 

A full discussion is probably worthy of several weeks or more discussion in a metallurgy course.

 

John

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of limesh M
Sent: Sunday, August 21, 2011 9:19 AM
To: Materials & Welding
Subject: [MW:12289] Uncontrolled heating and cooling effect of Carbon steel below lower critical temperature

 

Dear All,



Material : Carbon steels in between 0.008% carbon and 6.67 % carbon.

1.Is there any metallurgical changes(phase change) will occur other than pearlite,if I heat rapidly uncontrolled heating)low carbon steel just below or equal to lower critical temperature(723 C) as per iron-carbon equilibrium diagram?

2.1.Is there any metallurgical changes(phase change) will occur other than pearlite,if I cool rapidly (uncontrolled cooling, no quenching by any kind of liquid medium)low carbon steel from just below or equal to lower critical temperature(723 C) as per iron-carbon equilibrium diagram?





Regards,

Limesh

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