BEG: How do you case-harden steel?

[Aaron]

Howdy,

How do you case-harden steel?

Valentine Armouries has a video where they "put it in a wood fire for awhile" to case harden it.

Does anyone have a referance on how to case harden steel?

Thank you for your time,

Aaron

[muttman]

I`d be interested in the answer as well; I`m considering case hardening my riveted mail shirt when it comes from Ancient Armoury. Has anyone done this before, and what would you say the pros and cons would be?
John

------------------
"and the springfieldians heroicly slaughtered there enemys while they prayed for mercy!"

[Loren Patterson]

ok, I officially looked it up in my Machinery's handbook, and it says that case hardening consists of carburizing and hardening.. to carburize (add the carbon) a iron pot is used. something you can seal with a lid. the iron pot is baked at a red heat (about 1600 degrees) with the item inside with a carbon material is packed around the item.. like charcoal or a carbon based substance.. this is baked for hours it says.. the item must reach the 1600 degrees.. basically its supposed to be at the critical temperature of the steel.. and after you preform the carburizing, you would harden it by heating it up again to critical temp and quenching it in oil or something. the drawbacks to doing this to maille is that at a temperature of 1600 degrees.. you pick up the maille garment, and it will fall apart because the rings are very soft.. maybe this worked with riveted maille but ive never tried to pick up a glowing red riveted maille garment.. but i imagine butted maille would just be ruined.
- Loren

[Rainald]

ive never tried to pick up a glowing red riveted maille garment.. but i imagine butted maille would just be ruined.

I have picked up a glowing red butted hauberk before. Not a really fun thing to try and do without destroying quite a few links in the process. Due to the fact that it softens them so much. Plus picking up a 20-25 pound pile of flexible red hot metal is not the easiest thing to do safely.

[Sasha]

You do not need to pick it up at all. It rests buried in potash inside the sealed CERAMIC vessel (iron is not a good idea).

You would let it cool naturally in that state and then re-heat it in a furnace on a slab. You then either slide off the slab into your quench or just dump slab and all (not as good an idea, but lots more steam and sparks).

Case hardening is, however, not a good idea for maille because it does eventualy wear off by the process of the rings rubbing on eachother. Case hardened materials also tend to be brittle shelled rather then having the flex and return of tempered carbon steel.
Good for chunky tool steel items...bad for fine wire applications like maille and watchpins.

Somewhere in my course notes from blacksmithing Ii have the various mixes for doing case hardening stuff in a coal forge/furnace. If I ever find them I will happily give specific answers.

I am not sure what in hell Rob is actually doing by throwing stuff on a woodfire. He could be blackening it or burning off the zinc or even annealing the metal....He is not case hardening it.

Sasha

[Ideval]

Hearsay caution:
I've heard of "painting" on a liquid preparation, or perhaps it was a paste?, then baking the piece.

The way it was explained left me thinking that the skin or surface of the armour "absorbed" or was "penetrated" by the carbon preparation; this super-thin surface, now with enough carbon to temper, would then be tempered.

As I understood it, this temperable zone was about 2/1000's of an inch thick.

Idëval

[Sasha]

It sounds like a paste I know of. It is used mainly for aluminium.
Basically it calls itself a "scratch resistent" coating. Sort of like powder coat crossbred with anodizing (bad example...but I mean that it actually bites in by a couple of molecules like anodizing but is applied in a manner similar to powdercoat).

I have never used the stuff.

Sasha

[Dwarlock]

there is a product called casinite, used by blacksmiths, it may be the paste you're talking about. I've never used it, but from what I hear it's quicker than the origional method, but also doesn't harden as deeply, and it's seriously poisonous.

[Norman]

Righto --
My shop techer in High School showed this method to me --

Essentially, Casenite is a powdered carbon (with whatever junk added in).

You red heat your piece and the burry it in the powder -- the powder gets absorbed as a thin outer layer.

as for case hardening armour -- i seem to remember something about Grenwich armouries using a thin "tin foil" of high carbon ontop of mild for a sort of case hardening effect.

------------------
Norman J. Finkelshteyn
Armour of the Silk Road - http://www.geocities.com/Athens/Olympus/3505
The Silk Road Designs Armoury - http://www.enteract.com/~silkroad
Jewish Warriors - http://www.geocities.com/jewishwarriors
The Red Kaganate - http://www.geocities.com/kaganate
silkroad@spam.operamail.com (remove "spam" from e-mail to make it work)

[Patrick Thaden]

Let's see, In the process of case hardening you are infusing enough carbon into the outer layer of your low carbon steel so that it may more easily be heat treated. There are three basic ways to do this pack, gas, or liquid. The thickness of this layer can range anywhere from .005" up to .250" it all depends on the saturation time and the way it is cased. If you are using thiner wire or plate, you can actually infuse enough carbon to turn it into a piece of high carbon steel meaning it can be hardened and tempered as such. Today case hardening is done, for one, to keep expenses down on pieces that may need to be heat treated but not throughout the thickness of the piece. that way you don't have the expense of the high carbon chunk of steel. One other example I have been told about is the WWII steel helmets, formed of mild steel and then case hardened and heat treated(no proof though). If done right it should leave the outside quite hard and the center soft. Same idea as some sword blades and other cutting insturments hardened steel where it is needed backed up by a tough flexible core. I personaly don't see any need to harden riveted mail. The rivet were placed because they new the wire wasn't that hard. In Stones Glossary he mentions japanese mail not being riveted but being made out of a higher temper steel? Take it as you will. I will actually be taking a helm to a local heat treater soon to have the piece cased. That way I don't have the cost of the highercarbon steel but I get about the same results.

------------------
Patrick Thaden
Thaden Armory
http://www.thadenarmory.com

[Steve S.]

Here is an exerpt from my article on maille wire:

<i>At least some maille garments were case hardened and tempered, for specific mention of this is mentioned in the publication Natural Magick Book XIII, in 1558:

"Take soft iron armour of small price, and put it into a pot, strewing upon it [soot, and organic powders to supply carbon], cover it, and make a good fire about it: then at the time fit, take the pot with iron pinchers; and striking the pot with a hammer, quench the whole herness red hot in water; for so it becomes most hard ... But, lest the rings of a coat of male [maile] should be broken, and flie in pieces, there must be strength added to the hardness. Workmen call it a return. Take it out of the water, shake it up and down in vinegar, that it may be polished and the colour be made perspicuous: then make red hot a plate of iron, and lay [it] upon the same: when it shows an ash colour, cast it again into the water, and that hardness abated, and it will yield to the stroke more easily: so of a base coat of male, you shall have one that will resist all blows."(11)

This suggests that some maille was at least partially converted to steel after assembly, and done so specifically for the mechanical advantages of hardened, but tempered, steel. However, according to Dr. Williams, no armour to date, maille or otherwise, has been analyzed and thought to have been carburized.</i>

You can see the entire article here:

http://www.forth-armoury.com/research/wire/authentic_wire.htm

Steve


------------------
Forth Armoury
The Riveted Maille Website!

[Arland]

If you guys want a detailed set of instructions on how to caseharden, harded and then temper maille, shoot me an email and I'll send you out the file. It really small and has lots of information in it.

------------------
Baron Arland the Bastard
http://clubs.yahoo.com/clubs/rivetedmaille