Forging cracked 5160

W

watakipoma

Joined
Feb 5, 2003
Messages
70
OK, here is what is happening to me:

I've started the charcoal forge and have had a wonderful time hammering hot metal. I'll get a nice (ok, something that looks like a Star Trek fantasy knife when it should be a clip blade...) blade and a full tang along with lots of little 2nd degree burns from flying scale :eek:

I'll anneal it in the forge and let the firebricks and ashes insulate it.

The next day or so I'll go back and start another blade. I'll look at last night's work and think I'll just "tweak" the tang a bit, get it straighter or flatter and BOOM, a huge crack appears in the second or third heat. :mad: :mad:

This is flat stock 5160, not leaf springs or coil springs.

Should I think of annealing in Perlite instead or is it something else?
 
My first guess would be that you are forging it too cold. Cracks like that are not normal in 5160....maybe shiny stuff but not 5160. It's real easy to say "just one more hit"

Second guess would be a bad lot of steel.

Third guess would be aliens :footinmou
 
peter nap said:
My first guess would be that you are forging it too cold. Cracks like that are not normal in 5160....maybe shiny stuff but not 5160. It's real easy to say "just one more hit"

Second guess would be a bad lot of steel.

Third guess would be aliens :footinmou
Click to expand...

Nah, I divorced the alien.... and I'm willing to bet that this is due to operator headspace.

It could be that I don't know what the steel looks like if it's too cold. I get it bright orange and it fades very quickly. Is that normal? How many hits or seconds does steel take to become too cool?

Thanks in advance.
 
How long it stays hot depends alot on the thickness and surface area of the steel. Round stock will hold heat longer then flat. I personally don't especially like working with flat stuff like leaf springs for that very reason. When I work with round stock by the time it's flat and losing heat fast it's almost done, while starting with flat means it acts like that before I even get started. If it has no glow then don't hit it (I can't say I always follow this advice myself, that last hit or two is very tempting). If you ARE going to hit it cold anyway, at least lighten up on your blows, don't actually shape the blade at that temp, just smooth minor bumps out.
 
It depends on the steel and other things. Sometimes I only get 3 good wacks and a cleanup hit or two.
The smaller the piece of steel (like a knife blade) the faster it cools. I love beating out large hawks because they hold their heat so well.
 
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