Air hardening 5160

G

Gib Guignard

Joined
Jul 8, 2001
Messages
849
My shop is totally open air and on a cold windy day I have found some differences in heat treating 5160. I normally draw the spine back with a torch and I have found a difference in results from mid summer (100deg+) and winter 40 to 60deg with a wind blowing. I get a nice spring temper but difficult to file without using carbide rotary files. Any one have any experience with this.
I have wondered if the forging was ground thin enough before heat treating if the air quench would yield a usable knife with a deferentially heat treated blade smiler to a edge quench.
Mete please tell us what is happening?
Gib
 
Gib I'm thinking in the cold you just can't keep the temp
up long enough to draw it the same as in the heat of summer
 
Dan, I tend to agree with you except that with the cutting edge in water I have heated the top 1/8" to dull red then backing the torch away slowly to slow the cooling rate and have found that in even moderate temps with no wind this has shown up.
I am going to go to a edge quench to solve the problem but am wondering about the air harding proprieties of 5160.
Gib
 
Gib it's the sun this time of year it's lower in the southern horizon:D

just kidding ..
is it possible when you draw it in the summer your just on the verge of the right draw and when it's a bit cooler it's not just there?

I would guess if you can get the steel to cool fast enough
no matter how you do it, it will harden. oil quenching or by air.

but the stuff I've forged in turn, once I put it out red hot
and let it air cool ( carbon steel) it tends to be hard anyway, I would think it would it would be soft..
so just drawing it back, for me anyway, takes a few times with a torch if I want it dead soft doing it that way anyway....
I heat it (the spine with the edge water tubed for full hardened blades) and draw it back to steel silver color
more than once depending on what I'm trying to get..
 
Dan, Yes I did it 2 or 3 times. This is what is so pusslzing I have done all the right things in the right order. Gib
 
:confused: it's got to be the temp. doing it, lack of moisture in the air or something.

on another note, on your acetylene, have you noticed
the drop in pressure in the cold compared to when it's warm
it goes down a lot.:) big time lot.:)
 
Dan just finished a test blade, haven,t done anything with it yet but the cutting edge did get hard. No my acetylene pressure stays the same hot or cold. More details later. Gib
 
Gib, Have you switched batches of steel? I was going to say some old fart things but I won't this time....... :cool:
 
Good for you Ray it's about time you learned to respect your elders.
This is a new batch of steel but I have noticed this for some time with other supplier steel. I have been noticing this for a while, wondering what was going on as this is not supposed to happen.
Gib
 
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