Using sugar to protect steel from decarbureization

How about corn syrup? Randy

Try table salt in a crucible. I tried it on some 4340 a couple of months ago and was extremely impressed. No scaling or decarburization at all.

Mark Rand RTFM

Do a search on heat treating salts. There are a lot of different salts that are used in heat treating. Some are fairly toxic though. Depending on the salts used, you can go from a few hundred F to almost 2000F. Todd

Hair shampoo works, but you may have to try a few brands to find one that works best. You might try shaving soap, but not the pressure bomb stuff.

Steve R.

I would think it would fare no better than straight sugar, as corn syrup is a bunch of different sugars in water.

All the stuff about using sugar in various forms for hardening got the metal no hotter than red or cherry red, all that's needed for ordinary carbon steels.

I just received the Kasenite. I've yet to try it, but I bet it contains some kind of salt that is molten at high heat, dissolves carbon, and sticks to the metal. May also contain clay.

Joe Gwinn

Hmm. That's an idea.

Also, I bet I could put the metal and some table salt in a pouch made of heat-treating stainless steel foil, and the molten salt would act as a heat transfer agent, allowing the torch to heat the whole thing, not just the foil.

Another good idea, one than can be combined with the foil pouch idea.

Joe Gwinn

Puff, and your foil is gone. :-)

Nick

sodium chloride melts at 1475F give or take a few degrees. So it's already in the right ballpark for most hardening uses. That, with its cheapness and relative safety, make it an easy thing to try out. (Note that safety refers to poisoning yourself, not pouring molten salt onto anything made out of wood, concrete or meat :-(

These are pictures of the test I did:-

I was experimenting with hardening some 4340 (actually BS 970 1955 EN24) by heating in the molten salt and then quenching directly into oil at 340F. The hardness at the surface tested to 54 HRC, which is about what I was aiming for. There was no scaling noticed, although the steel was blued from the oil.

The results were sufficiently good that I will probably build a couple of permanent salt baths, once I've got all of the current jobs out of the way.

Mark Rand RTFM

Mark Rand wrote: (snip)

Indeed. Also if what you are heat treating isn't entirely dry and you have a deep salt pot (like for heat treating swords), you can wind up with a molten-salt cannon. Not something to be close to.

With the right salts, you can quench in them too. And you can do fun things like high-temp quenching to get bainite.

300 series stainless is supposed to be good for salt pots.

Also looking around, this looks like a good design for a temperature controlled salt pot:

Todd

Didn't happen. That heat-treating stainless steel foil is pretty durable, and had no problem sitting in the flame at an orange heat.

It's rated for 1800 degrees F (= 982 C), which is just about the limit for propane-air in a little firebrick muffle.

.

Joe Gwinn