welcome to the world of wootz (or more appropriately, crucible damascus)..
I'll begin with a small introduction... I've spent alot of time in university studying the material and producing a similar substance for my undergrad thesis. Understanding my background, I will on occasion be quoting or referencing studies or specific accounts. My goal is to participate in the wonderful sharing atmosphere of this forum.... hope you enjoy !
Crucible steel
- it has been around for a longtime and was a facette of several cultures... Persian, Indian, Russian, etc
- therefore refering to the steel as "wootz" implies the Indian version of the material.
what is Crucible Damascus?
- there is no mystery... put in a simple way it is a slow cooled, carburetted steel. It is easy to produce following certain guidelines:
1) the carbon level is inbetween 1-2% for the ingot
2) the correct ingredients are in the mix
3) the period between liquidus and solidus is ample to form a third element network aiding in the formation of dendrites.
4) proper thermal anneal of ingot
Carbon levels
- I find this is one of the important key's to producing wootz
- you must be able to reasonably adjust the carbon content of the charge to 1-2% carbon.
- if you go over the 2% mark of carbon ...it will still produce a decent looking ingot but it will have a brassy appearance.. congrats... you have just made cast iron and will be virtually impossible to forge with out crumbling like a cookie.
- later on I will include a basic chemistry formula that I use to adjust the steel to be within acceptable wootz/carbon parameters.
Ingredients
Ofcourse I assume that you've seen the online study
www.tms.org/pubs/journals...-9809.html
- Look closely at the tables.... the elemental break down will set out parameters for your steels content !
- some ingredients are left at very low levels.... this is important to note !!!
-- but some ingredients have no negative effect on the dendrites formation... ( one example is Cr... one of my favourite damask's comes from a charge of 5160 and cast iron)
Liquidus/solidus
- Why the slow cool?
- Imagine a fully liquid, molten charge with a mix of many ingredients !!
As the temperature starts to decline... some of the elements (due to their nature) decide to solidify first before the bulk of the charge. The initial elements come out of solution and solidify form a network of sorts. If you can imagine a spiderweb of these elements forming in a pot of molten metal.
The web forms with the slow cooling and as the cooling progresses.... the carbides begin to grow on this structure. Similar to the dew on a spiders web in the morning !!
When the charge is fully solid, the network is apparent and you can visually see dendrites on the ingot !!
I have pictures but have to figure out a way of posting them?
How slow is slow cool??
- the range of accounts has been from a couple of minutes to 60 hrs... it all really depends on the characteristics you'd like in the steel.. (such as patterning/waterings !!)
-personally, I have cooled it many ways but now I usually just yank the charge out and wrap it in Inswool and let air cool !
Thermal Anneal
- very important
- watered steels are very odd in my experience and I would recommend doing things in a similar manner as the ancient smiths.
- damascus has a tendency to be a terrible substance to forge.... (very high rate of failure !!)
- with a thermal anneal it seems to decrease the red short nature of the material and produce a somewhat ductile rim around the ingot ( a decarburized layer)
- The anneal... personally, I place my cleaned ingots (previously made on another day) in the furnace after a day of melting and leave them in this oxidizing atmosphere overnight.. ( the shell of my furnace is significant and the ingots are usually very hot the next day)
- next day you are looking for a nice even mottling on the whole surface of the ingot (good color !!) or else do it again
- otherwise you could simply stick the ingots in a metal container and fill it with forge scale and stick this in the furnace. (for cool down/anneal)
The method of watered steel making that I'm about to describe is by using a medium carbon scrap steel for the bulk of the charge. The steel I've chosen is 5160 car leaf spring steel which will provide the bulk of material. The main problem now is to adjust the carbon level of the charge to decent damask levels. I will describe two ways that I"ve done this but will lean more on one method...
1) Addition of carbon:
-With this method you basically put your charge of med steel in a clay/graphite crucible
- mixed in with the charge is a measured amount of carbon ( I used aquarium charcoal)
- remember simple chemistry... the carbon is a percent weight of the total charge... therefore it must be adjusted with this in mind
- The charge is now covered with a half a cup to a cup of glass ( I use green wine bottles for this..)
- Finally the charge must be sealed in the A6 graphite crucible ... a) cut a small circle of Inswool (kaowool) fit to the mouth of the crucible
b) fit the circle in the crucible and then plaster the top shut with a 1/4 inch layer of 36 cement or satanite
- now charge is ready to fire
- the lid has never sealed perfectly air tight so there is no real pressure or moisture build up ( cross your fingers)
- the reason for the lid is to prevent the carbon being consumed by the oxidizing atmosphere.. (since carbon has an affinity for oxygen rather than iron)
2) Charge cut with Cast iron
- This is the method that I use partly because it's much simpler and less time consuming. (no fooling with plaster)
-The carbon adjustment in this case is supplied by added a measured amount or cast iron to the base charge ( to raise the carbon level to appropriate levels.... sounds simple!!)
-firstly you must use a cast iron ( around 3 to 5 % carbon)
- it is very important that you know the percent weight of carbon in the cast and the base iron. (or else formulas become even more of a crap shoot)
- get the specification from the place you bought the cast and use this number !!
- more than likely they will give you a range (high and low) for the carbon level... I just take the average of the two and use this nos for the Carbon level in the cast.
-now use the appropriate weight of cast with the base charge of 5160
- put into crucible and use glass to cover charge (1/2 cup)
- you are ready to fire the charge...
It is good to develop your own formulas but I will walk you through the basic chemistry that I used to create my "5160 Damask " forumula ..
Formulae Development:
- firstly I will tell you the method to my madness in developing this formula the way I did..
- I receive my cast in the form of a 16 lbs ingots which is severe to cut or crack a chunk of it off... (my chop saw is way to small ) therefore I sledgehammer it till I get a several pieces.
- I measure the weight of these cast pieces that i've cracked off and adjust the weight of the 5160, accordingly.... (since 5160 is easily chopped into size by my chop saw)
- This is important that you understand the above !!!.... because now you will see my formulae is to adjust 5160 levels ...
Formulae: "5160 Damask"
-developing ratio??
Cast iron ( 1lbs 2.5 Oz) = .525kg
5160 (3 lbs 4.5 Oz) = 1.491kg
cast iron C level = 4.15%C
5160 C level = .6%C
total C level:
Cast .525kg x .0415 C = .0217kg = 21.7g
5160 1.491kg x .006 C = .0089kg = 8.9g
total= 21.7 g + 8.9 g = 30.6g
therefore .525kg + 1.491kg = 2.016 kg total = 2016g of Fe
30.6 / 2016 = .015
.015 x 100 = 1.5 percent carbon level in the charge..
(now we know the weights of both metals to make a charge of 1.5% carbon )
(Translate this into a usable ratio... ???)
simply done !! .525 / 1.491 = .3521 .... (the magic nos)
Formula to adjust 5160:
(xxxx) of cast iron / .35211 = (xxxx) of 5160
to test the formula.... I've got .525kg of cast broken off and need to know the amount of 5160 to mix in..??
there fore.. .525kg / .35211 = 1.491 kg of 5160 needed for charge to have an end product of 1.5% carbon watered steel.
-The cast used in my charge is sorel because it is a very good quality material and available here....... you can make it with other casts of known levels (of elements) and produce your own formulas easily.
Remember... This Formula is adjusted for Sorel cast iron.... you must adjust this for the cast available to you !!!!
Experience and Advice:
Watered steels are often thought of as an impossible material to create and that the recipes are long lost. It is wrong to believe this..... Breant simply described it as a "carburetted iron" .... and if he could recognize this back then !!
creating the ingots is only a very small step in the making of a usable blade !! Wait until you try to forge this material.. the ingots are very hard (almost like striking the surface of your anvil)... and the steel is unforgiving at the temperature it must be forged at...
- too cold and it will crack !!
-- too hot and wootz juice ..( a juicy appearance to the ingot indicating that some material has liquified and is running out.) Soon after this... your ingot will become easy to forge and then it will crumble like a cookie.
- even when you do everything right.... you must forge the ingot with good technique.... or else wootz has a way of cracking on it's own.. ( almost similar to the delamination that occurs with pattern welding -slippage)
this is why sword length are hard to come by...
I have written on the forge techniques but I believe this to be a whole new discussion....
ps.. remember to follow furnace safety around molten steel
Seriously, though, Ed is a class act.
