[TheForge] Re: Burning Metal

Mon Nov 3 22:27:01 2003

The short answer is: The oxides produced must have a lower melting point
than the base metal.

I don't know at what % C the oxides make cast iron "uncuttable" with a torch
nor exactly why, the graphite hypothesis sounds reasonable though.

Regardless, you can see the action: preheat melts the base metal, the oxy
jet hits it and a layer of hard slag/oxides form and the oxy jet has to
physically push the oxides and molten material from the cut. This isn't
cutting, it's more like excvation, soften it up and push it out of the way.

Pure iron cuts just fine and any problems cutting wrought would be the
result of silica inclusions. Silica and or glass may have a lower melting
point but their oxides are very refractory also even in a molten state
silicas ave very viscous so they don't even push out of the way very well.

Frosty
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

----- Original Message -----
From: "Andy Gladish" <[email protected]>
To: <[email protected]>
Sent: Monday, November 03, 2003 10:00 AM
Subject: [TheForge] Re: Burning Metal

> > I think if the carbon content was the accelerating factor, cast
> > iron should
> > cut easily.
> > The  best I can do on cast iron with an O/A torch is a very sloppy cut.
> > My plasma torch however cuts it easily.
> > chuck-
>
> I think that what is happening when I use an O/A torch to cut cast iron is
> that the preheat is melting the metal and the oxygen jet is blowing it
> aside. Way different from the sharp, clean cut (burn) I get with steel
when
> things are set up correctly.
> So, a torch will 'cut' things that it can't 'burn'.
> Andy G.
>
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