opinions on anealing metals

[IronDawg]

I know Ivan Boggs would just take a blank as soon as he was through forging it to his taste and throw it in a pile of ashes and walk away.

I have a pile of sand next to my forge that I job my works down in and leave for the night.

On another site I was reading where a fella uses vermiculite.

What are some of you guys opinions on anealing mediums and such to slow cool blades?? what do yall use??

Cuz I'm thinkin if ashes are good enough for Ivan Boggs then I'm a dummy for not using them myself. Cuz it aint like my forge doesn;t make plenty of em.

[melsdad]

I believe ashes will retain heat better than sand for the slow cooling needed to anneal the steel.

[LRB]

Vermiculite is a better insulator than ash, but the method of annealing can depend on the steel. If it is a hypereutectoid, having more carbon than .80/.84, you can be better off with a series of sub-critical heat cycles, letting the steel cool to ambient in between cycles. This will  spheroidize the carbon, making the steel softer than a slow anneal. This is best done after  normalizing with progressively lower heats starting with around 1550° and going down to just above critical in order to get the carbon dispersed evenly before the sub-critical cycles. A quench on the last normalizing, or a quench after a soak, is even better, as this will lock more dispersed carbon  in place, and react better to the spheroidizing. A slow anneal of hypereutectic steel will produce layers of pearlite and cementite, which will still eat drill bits like candy, but may bend easily. The spheroidized carbon lets a drill slip by with little or no appreciable resistance.

[IronDawg]

LRB,

I bet you can't say that in english!!
Nah seriously I think I understand what you're sayin. The method you're describing keeps the metal uniform in it's make up right? no carbon migration?

[LRB]

You got it Dawg. Get the carbon evenly dispersed, lock it in, by air cooling, or quenching it is best. then cycle at sub-critical heat, which in this case is around 1250°/1325°, or at least below non-magnetic, which is 1414°. The carbon forms balls and allows and allows easier drilling. 01 steel comes spheroidized annealed, and thats why it is so soft you can carve slivers from it with a sharp knive.

[IronDawg]

OK two questions, are you water or oil quenching and considering this sounds like as close to a 100% anealing process as possible how hard is it to get a good temper back?

[LRB]

All you would be doing with the process above is putting the steel in a better condition for drilling holes or filing it. You still have to go through the hardening and tempering process afterwards. If you don't need to do any drilling, or a lot of filing, it is really not necessary, as long as your standard heat treat is good. This anneal works best with steels at or over .80/84% carbon, but can be used on lower carbon steels, if your slow anneal does not soften the steel enough for easy drilling. I oil quench only, but I only use 01. Carbon forms balls beginning around 900°, and continuing to the Curie point, non-magnetic, which is 1414°, where it then starts going into solution again.  The one draw back to this type of anneal, is that these carbon balls do not go into solution as fast as layered carbon, and need at least a short soak of a few minutes at quench heat, which should be around 1475°, to 1500°, if for simple steels. If not in a temp controlled oven, that would be about 1 or 2 shades of red above non-magnetic. In the case of 01, it needs a 20 minute soak at minimum, whether it is annealed or not, because of the alloys it contains.

[jmforge]

Ashes and sand tend to draw moisture, so you may end up with hard spots.  Vermiculite is the best bet if you don't have a heat treat oven. I use a short galvinized steel trash can to hold it.  Make sure your change it out every so often, because it will eventually absorb some moisture and start caking up.
 The best way to do it is a subcritical sphereoid anneal.  Take it up to say 1250-1300 and then let it cool at around 10F per hour down to below 900.  It is essentially a super hot temper which happens your steel formed up into nice little spheres.  Some "oil hardening" alloy steels  like O1 or 52100 will air harden a bit when you heat them, so even though the are still "soft" they can have a thin skin or spots of hardened material on the surface that will flat eat up your drill bits.