salt pot questions

[jdm61]

A few questions for those of you who use high and low temp temp salts.
1. Do you use the salts for all thermal cycling.....that is annealing, normalizing and quenching?
2. Which steels will not harden fully in a low temp salt quench?
3. A follow up to question one. I have read that scale does not form in the salts because it is an oxygen free "environment". Does it form when you take the blade out of the high temp tank and expose it to air and if so, would you have to remove this scale before putting the blade back in the tank if you were doing normalizing cycles? Also, if you were using salts to heat for annealing, would puting a blade with forge scale in the salt be problematic? I have heard that plain old rust contins water and can cause some pyrotechnics.
4. Are you restricted to fully quenching the blade if you use salts? I know that clay coating would not be a good idea because it contains LOTS of moisture.
Thanks

 

[NickWheeler]

Hey Joe, stop by 26-R and/or see me in the pit and we can talk as long as you want about this.

To answer your 4 questions:

1.) I rarely anneal anything anymore. The few steels that I ever bother annealing are 52100 and Champalloy L6, but I don't even need to with 52100 to get out of it what I want.

I do use the salts for all of my initial thermal cycles. Let's say a W2 blade

I'll forge it to shape, then normalize it once or twice in the forge. If I have time, I'll set the blade in a tube of vinegar to eat off the scale. You don't want scale in the salt. If I don't have time, I just grind it off, but I don't try to get much of anything established.

Then I'll go to the salt and do a stress relief run at 1650-1700. I don't think this refines grain at all, but I do feel it helps alleviate some stresses.

Then I'll run it through at 1600, 1500, and 1400 three times. This leaves me with very fine grain and low hardenability, which I like for clay hardened blades.

Steel like 52100 and O1 are really awesome for austenitizing in the salt. I like to soak them for 15-20 minutes at temp before quenching.

If I want to fully harden the simple steels (w1, w2 etc) then I will austenitize in the salt.

If I'm doing a clay hardened blade, then I'll austenitize in the Paragon or my forge set-up with a thermal couple. Sometimes if I'm feeling up to it I'll austenitize a blade in the forge and simply watch for shadows and forget about all the "high tech" stuff.

2.) Just about anything will harden in low temp salts, but if you want to quench in them I'd stick with steels like L6, 52100, and O1. I don't hardly ever use the low temp anymore. I like the Park #50 and AAA oils.

3.) No, you don't get scale in the salt. When you take the blade out, there will be a very thin coating of salt on it, and it will not form scale then either. The houghton salts I have do create a $hitload of rust on the blade within DAYS if I don't get the blade cleaned very well and ground. I'm told the Heat-Bath products don't do this, and thankfully I finally have someone to get the Nu-Sal from. I'll be switching over to that after Blade.

4.) I sort of answered this in 1, but no, you are not limited to that. Actually you can get some really neat hardening lines by austenitizing in salt, and quenching the blade before the thick parts are at temp. Because of the nature of salt, the thin edge will heat up to temp first and be uniform. It only takes a couple minutes at most though. Salt is fast and will have that blade at a uniform heat in short order.

I used to put clayed blades in my salt. The moisture is not a problem, you just put the clayed blade in your kitchen oven at 4-500 F for about an hour and the moisture will be gone. The problem for me, was that it was leaving lots of gunk in my salt. The your salt starts decarbing your blades, and since getting away from that is part of the reason you use them to begin with....


Hope I cleared that up

See 'ya at Blade!