Burning the carbon out of my blade

madpawn

madpawn

Joined
Jan 5, 2017
Messages
36
Hi all, I'm new to forging and one question I have is: How many times can I heat 5160 before burning the carbon out of the blade? I've heated it a dozen times already to 1700F and I'm still not finished. I also fear that I'm stressing the metal too much with my inexperienced pounding and hammering. How can you tell if you need to scrap and start over?

Edit - another thread states that carbon loss is negligible except at the surface where it flakes off as scale. I'm still not sure if I am mangling the metal but I guess I will find out after the quench.
 
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You will a get scale [iron oxide ] layer , then a decarburized layer. Both will have to be removed ! Watch temperatures carefully and make every hammer strike count . If you are using gas , adjust the flame to the reducing side to minimize problems !
 
It would take an oxidizing atmosphere and hundreds of hours continuously at 2000F or more to burn all the carbon out of the blade. Multiple heats only affect the surface ... as pointed out in mete's post.
 
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Thank you Mete and Stacy! I am using a coal forge and .25" X 1.5" X 36" 5160 steel. It seems to cool very rapidly (and it has been hot outside ~93 F ). The scale that is coming off is fairly large. I believe I'm heating it to about 1700. I tried 1625 but can only get a few hammer blows before it cools below 1600. I am going for a short machete type chopper and trying to widen the blade to 2" (starting with 1.5") but it may not be possible. I fear the blade will be too thin. Should I have started with 2" wide stock if I wanted a 2" wide blade? I thought 1/4" would be thick enough to draw out but with the scale I'm losing and later grinding, I fear that I may have to settle for something smaller like a hunting knife.
 
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Since most machette are only 1/8" a bar of .25X1.5 should easily draw out to 2". Also, you can leave the spine thick if you want, as just drawing the bevel will add 1.2'
 
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