Heat treat set up.

[Ray Cover Jr]

I tried a search for this info and came up empty. I am not a newbie to knifemaking. But I am to heat treating. I have always outsourced my heat treating in the past.

I figured this was as good a place to ask as any.

I am looking into setting up my own heat treating system. I am mostly interested in doing large carbon steel blades with an ocasional 440c here and there. I have heard a lot of guys go on about using a kiln and salts for carbon steels to cut down on scale. What all is involved in such a salts set up (equipment, cost, can I do it in my garage or does it need to be kept away from the house etc.) Keep in mind I have very little previous knowledge about this setup so I am looking for details.

I understand that for the stainless I will either have to have a separate setup or continue to outsource that. Is this true?


Thanks,

Ray

[SteveS]

Ray,

High temp salts are the way to go - IF you are comfortable with extremely dangerous systems and caustic, creepy materials. Frankly I think they are for the big boys with lots of blades. (I talked with someone that experienced a mild explosion with 2000 degree salts. Not pretty. Scared me off.)

I use an oven for stainless and carbon, costs more in electricity, but not nearly as dangerous.

FWIW

Steve

[Ray Rogers]

I agree with Steve. In addition to the problems he mentioned with salts add the fact that the salt pots have to be isolated to avoid causing corrosion to every other machine and tool within reach. Salts are highly corrosive to metals (big news flash!).

Also, you can't just quickly heat up a salt pot and treat one blade that you just found out you needed to make right away. An electric oven is much more flexible with your schedule and cheaper and easier to set up, house, and operate. Scale is a fact of life for most of us but, like everything else, you learn ways to handle it .......

[Ray Cover Jr]

Thanks guys, thats exactly the kind of thing I needed to know.

Ray

[Stormcrow]

Or there's the cheap and easy scale prevention method of closing off one end of a steel pipe, tossing in a handful of sawdust, wood shavings, or crushed chunk charcoal, heating it in the the forge, and heating the blade inside the pipe to harden.

Unless you're grinding blades and not using a forge. Then it might pose a problem.

[rlinger]

For stainless get an oven and foil wrap. For high carbon an oven or forge. Using a forge will require a different learning curve but the forge will not work for stainless, however it will lend itself to the next step - forging.

Particularly for stainless, also get a good dewar for cryo. It is also advisable for high carbon. Medium carbons such as 5160 and S7, as an example, may not benefit from this.

The pipe idea will not hurt at all. For stainless use foil wrap. I have used open end foil wrap for oil quenching steels (the pipe idea except a open ended foil wrap) with marginal but beneficial results. This allows you to remove the steel from the packet quickly for quenching. Put a very small piece of combustable in the bottom of it. Too much will create a low pressure area and tend to suck new air in. Experiment. Do not use open ended pipe or open ended foil wrap for stainless. Air quench stainless in the packet. Do not take the time to remove the steel from the packet. Get the packet to rapid air flow immediately and allow to cool to hand warm ONLY before placing in snap temper, followed by cryo. The most important immediate part of quenching is just that - immediate. Taking time to remove from foil will kill you.

I recently had the pleasure to aluminum plate quench a couple folder blades. I did it because the blades were not beveled so all the blade was flat and parallel. Because of that it worked well. For beveled blades I do not quench with plates. If I do the ricasso will quench well. What about the edge that never sees the plates?

RL