Forging question

Alarion

Alarion

Joined
Nov 26, 2001
Messages
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I use C70, which is about the same as 1075 for forging. Doing this in my attic, in an apartment house, I can't do too much noise.
I have a 70# anvil set up on a wooden log stand. I cut blades out a plate of metal of the intended thickness and forge in distal taper and edge bevels, and something of the tang.
To do a reasonably sized knife, let's say 10" long I have to heat it in sections 6-8 times. Each section gets heated about two times this way.
Then I normalize 3 times, then heat to non-mag and quench.
I use a venturi burner powered one brick forge which can't even get near welding heat

How much carbon am I losing this way?

How much carbon I may expect to lose for each heat to forging temp (above non mag, to bright orange)?
And while normalizing?

Maybe I'm making of decarburization a bigger issue than it realy is
but not knowing I can't really evauate this, so here I am asking the pros :p
 
So long as your not heavily soaking or something weird while forging, next to none. All of it will probably be on the very surface anyway. You probably shouldnt think to much about it, unless your getting something weird happening and yure sure its due to carbon loss.
Keep in mind if C70 doesnt have as much manganese or even the other little trace alloying elements it wont *seem* as hard as 1075. Dont confuse abrasion resistance with hardness.

Joe
 
I say you are not losing any carbon. If you forge for several hours the content will drop but at much higher heat. These mosaic damascus knives we all make soak at welding heat off and on all together for about 4to8 hours and they still have plenty of carbon to harden. I havent experienced the carbon going to the surface as Joe is saying.

You forge in the attic? I bet the people downstairs wonder what the thumping is?
 
LOL!
No, the anvil sits on one of the reinforced concrete beams, and is directly above the bedroom below, which isn't used by day, so it causes almost no trouble :)
Anyway I already asked permission to my neighbors and told them to feel free to ask if they need something sharpened or a knife done :)
 
Originally posted by Bruce Bump
I havent experienced the carbon going to the surface as Joe is saying.
Click to expand...

I meant the carbon loss being on the very surface. :p Because of the way carbon moves around if you had any it would only be on the very outside, and not enough loss to worry about at all!
 
Lets use the right terms. Decarburization is time and temperature dependent. For the most part it occurs above the critical temperature. That means at hardening temperature( Though the time there isn't great) and during forging. Don't hold the steel above critical temps any longer than necessary.
 
Alarion,
Rest assured, you will only be getting decarburization (loss of carbon at the surface) and oxidation (scale) on the surface of your blades, for what you are doing. When it comes time to true up your blade through grinding, both effects will be ground away and you will have your 'regular', 'good' C70 underneath. Worry not, you are doing things properly. :cool:
 
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