[TheForge] Re: Test mail

[James Binnion]

On Nov 11, 2005, at 7:00 AM, Bruce Freeman wrote:


>
> When you talk about atoms and crystals, "compressing" doesn't  
> compute.  "Distorting", especially with metal crystals DOES make  
> sense with respect to crystals (but not atoms).  Also, I believe  
> that you can reduce crystal (i.e., grain) size by hammering, but  
> I'm not certain of that.

Any form of cold work breaks up the large crystals into smaller ones.  
Smaller crystals results in tougher structure with some improvement  
in hardness and tensile strength
>

> The carbon in steel is not free, but dissolved.  Carbon steel is an  
> alloy.  Hence, it is not an issue of the carbon compressing -  
> that's no more possible than the iron compressing.  The atoms don't  
> get closer together, except to a small extent when crystal FORM  
> changes (which is a whole 'nother issue).  Insofar as small  
> crystals are "closer together" than large crystals, reducing the  
> grain size makes the crystals closer together.  I am under the  
> impression, however, that it is the size of the grains, not their  
> closeness, that renders the metal hard.

It is the type of crystal structure more than the size that results  
in hardening of steel. Iron and carbon will form different crystal  
structures depending on temperature. By controlling heating  
temperatures and cooling rates you can "freeze" the crystal lattice  
in a particular form. For a simple description of forms of carbon at  
temperature in iron go to http://www.gowelding.com/met/carbon.htm .  
There are many volumes written about these interactions if you want  
to go deeper. A very good book for blacksmiths and other metal  
artists is Metallurgy for the Non-Metallurgist by Harry Chandler  
ISBN:  	0-87170-652-0 Try to find it in a library or a used copy as  
it is too damn expensive to buy new ($164)

James Binnion
jbin at well.com