Jump to content

Blister/shear steel


Recommended Posts

Whereas wrought iron is pretty easy to come by for me, shear steel is a whole other thing. So unless anyone knows were I could find any, what's the most practical way to turn wrought into shear steel? I was thinking of making thin rods of wrought, say 2mm in thickness, and then heating them up to about welding temperature for some time (say half an hour f.e.) in a charcoal fire. Will that give a good result? Is it necessary to wrap them in a clay jacket to keep any oxygen out, or is a good reducing charcoal fire sufficient enough? Basically I'm looking for something that takes the minimum of effort and fuel consumption.

Link to post
Share on other sites

I've been looking for information on the same subject, some of the better information I've found was from running a search here...

this is a good one

another good one

and another

The consensus seems to be 2 to 3 hours at 2200f in a sealed container with a carborizing agent.

I plan to try it in the near future, I have more wrought iron than I can use, some of it is really clean material that should make a quality steel if I don't screw it up.

 

I figure, while it's soaking, I could do some forging...

Link to post
Share on other sites

I don't know, 3 hours at 2200 seems excessive to me. It depends on how you look at it. I have put a thermocouple in the can so that I can accurately measure the internal temps, but it can take an hour or more for the center of the can to get up to heat, depending on the size of the can, ect. So I suppose you could say that you would soak it for 2 hour or so, but the whole can would be at temp for a much shorter period of time.

 

You can do it in a charcoal fire with no can, but that's a right PITA, OK for really small stuf, but you gotta keep it in the reducing portion of the fire, and make absolutley sure that the fire is deep enough that no O2 gets to it. If you can keep ALL the O2 away, the steel comes out cleaner than it went in. If O2 does get to it, you get "blister" steel, which is ok, but much more of a pain in the rear end to work with.

 

Lets pu tit this way, the first time I carburized something, I pu it in an open can full of charcoal, let it cook @ 2100 for 20 minutes TOTAL, and that 1/8" bar was good to go. The center wasn't fully carburized, but hey, fold it once, and you got a high carbon edge.

 

I talk a little bit about carburization in this thread:

 

http://www.bladesmithsforum.com/index.php?sh...esse+frank+seax

Link to post
Share on other sites

For references on historical processes, I'd check out Steelmaking Before Bessemer, Vol. 1 by K. C. Barraclough volume 1 covers blister steel very thoroughly. You'll probably need to get it via ILL, as it has gone out of print. I haven't had the opportunity to look at it, but there is also a free down load available on the internet archive, www.archive.org, The Cementation of Iron and Steel by Dr. Frederico Giolotti - from the early 1900's.

 

I know Rick had volumes 1 & 2 by Barraclough when he taught a class at Quad State a few years back.

Link to post
Share on other sites

HOLY COW JESSE! That seax was AWESOME! I sure wish I had been here for that. ;)

Link to post
Share on other sites

I've picked Ric's head excessively about this, and it's all about time at temperature. The hotter you go, the shorter you need to do it. Sheffield used a 1600 or so degree fire, and left it running for days. You can do 2200 for hours, and walk away with good product. My experience is limited, and I don't have a thermocouple so I don't know exact temperatures, but I was using a 1/8 thick square tube, and pretty much destroying it in the fire... running what I guessed was in the neighborhood of 2000 degrees, for about 4 or 5 hours, to get a good enough product. And I considered "good enough" to be on the lower end of the carbon scale. I was making a sword, but if I were making smaller knives, I'd want a higher carbon product.

 

Much depends, too, on the carburizing material you have. Charcoal powder will work, but it's not the fastest material. Parks Metallurgical #21 is what I used, which will work faster than plain charcoal carbon. The really exotic stuff has cyanide and barium in it to accellerate the process, which will cut soak time drastically, but it's not something I want in my shop.

 

Ric suggested to me some books by Kenneth Baraclough, on the subject of Blister Steel.

 

Good luck!

Link to post
Share on other sites

Right, It depends on many factors, time, temp, steel dimensions, alloy composition, ect.

 

You gotta be careful running this stuff at those temps, its REAL easy to make cast iron, or at least it has been for me. Basically what happens is that the stuff takes up enough carbon to lower it's melting point to at or below you soak temps, and you get a pool instead of a bar. Ask me how I know :rolleyes:

 

I've never had a problem carburizing with just charcoal or leather strips. What you've got to remember is that your carbon medium doesn't do the work while it's solid, it's the gas that does it. You're still basically gas carburizing. There is actually very little of the solid material that get's burnt, if you do it right. It's pretty neat.

 

I'm glad you like that seax :)

Link to post
Share on other sites

Thanks! That's some good information. Naturally the thickness of the material will affect the time considerably. And I guess the slag in wrought will act as carbon migration inhibitor.

 

Jesse, did you base the leather on Theophilus b.t.w.? He describes a carburization for small files by wrapping them in old pig fat and leather, covering that in clay.

Link to post
Share on other sites
what about ..say.....reducing the carbon in a piece of cast iron has anyone ever tried that?

 

 

That's a method used extensively from between about 1400 AD to the 1860s in the western world to make wrought iron. It can be done in a finery forge or (after about 1750) in a puddling furnace, in both of which the cast iron is bathed in molten slag until the carbon burns out. The trick would be guessing exactly where you are in the process. Well, that and building the finery/chafery/puddling furnace. ;)

 

In the old days they called puddling "pig boiling," since it involved putting the preheated cast iron pigs into the molten slag, which would then bubble violently as the carbon burned out. They knew it was ready to be wrought when it quit bubbling and became a pasty mass. I guess you might could have pulled the incipient bloom shortly before the boiling stopped, but to my knowledge that was never done.

Link to post
Share on other sites

Alan, on one of my old books "l'arte nei mestieri - Il fabbro" (arts and craft - the blacksmith), written in 1920 by prof. Isidoro Andreani, is mentioned that some steels were made in a puddling furnace, stopping the process before all the carbon was gone. It's written that the steel made in this way was called "puddled steel" and reading seems to me that it was a cheaper product than case hardened, used mostly for agricultural tools.

Link to post
Share on other sites

thanks alan. i caught an earlier post by don mentioning making steel out of cast via forge welding, but he only teased at the process. and thus lead to me having all kinds of fun with a bunch of cast one evening after work . i did learn that it ,(contrairly to my prevous beliefs) , forges rather well at a low temp. and it even seems too (please corect me if i'm wrong) to forge weld at a red orange color. but it may have just mashed together. ah well . i have been considering crumbling a bunch up and forge welding it between some wrought and layering it up a bunch and seeing what would happen. anyone evet try this? :huh:

Link to post
Share on other sites

"Parks Metallurgical #21 is what I used, which will work faster than plain charcoal carbon."

 

 

Christpher.

 

I had seen on your website that you had used Parks #21. Did you get this directly from Park, or another source. I'd like to try some. Thanks ~Herb

Edited by Herb Kettell
Link to post
Share on other sites
thanks alan. i caught an earlier post by don mentioning making steel out of cast via forge welding, but he only teased at the process. and thus lead to me having all kinds of fun with a bunch of cast one evening after work . i did learn that it ,(contrairly to my prevous beliefs) , forges rather well at a low temp. and it even seems too (please corect me if i'm wrong) to forge weld at a red orange color. but it may have just mashed together. ah well . i have been considering crumbling a bunch up and forge welding it between some wrought and layering it up a bunch and seeing what would happen. anyone evet try this? :huh:

 

 

That's one method of making the billet for a Japanese-style sword, actually. Due to the magic of carbon migration, if you were to layer up cast and wrought and soak at welding heat, the carbon would even out pretty fast. Of course, depending on your ratio of wrought (usually around .2% C) to cast (3 to 5% C) you could end up with a very high carbon steel.

 

There's also the old trick of steeling an iron plow blade by getting it white hot and "painting" a thin preheated cast iron rod over it. The cast will melt onto the wrought, and once again carbon migration makes steel.

 

I suspect what you're seeing with the forging of cast is that you're getting it to the mushy stage between solid and liquid, so welding may not be the right term, since with the carbon over 3% it will melt before it gets to a white heat... Whatever it is, please continue! I really like the idea. You've reached the edge of my direct knowledge, and all else from me would be speculation. You having done it makes you the authority. B)

 

And Herb, I think Chris got the Parks carburizing compound from Ric Furrer. Ric probably bought a 55-gallon drum of the stuff knowing him. :lol:

Link to post
Share on other sites
thanks alan. i caught an earlier post by don mentioning making steel out of cast via forge welding, but he only teased at the process. and thus lead to me having all kinds of fun with a bunch of cast one evening after work . i did learn that it ,(contrairly to my prevous beliefs) , forges rather well at a low temp. and it even seems too (please corect me if i'm wrong) to forge weld at a red orange color. but it may have just mashed together. ah well . i have been considering crumbling a bunch up and forge welding it between some wrought and layering it up a bunch and seeing what would happen. anyone evet try this? :huh:

 

I do not think you are welding cast iron at a low red heat. Judging the temperature of my forge (by eye) seems to be a real problem for me. I have lost two little wootz cakes during the annealing process, one melted and oxidized the other squirted some of its inner self out of the deoxidized shell.

 

To get a better idea of forge temperature, I now routinely place a bit of cast iron on a flattened piece of low carbon or wrought iron, and hold it in the forge. This needs to be fluxed or the shape of the cast will not change even though the inner mass has melted (hey that is just like the last wootz cake). What I am finding is grey cast melts (in about 30-50 seconds) into a very low viscosity puddle, some very fine sparks seem to escape through the flux and when pulled out of the forge it appears effervescent (that is either the Silicon or Carbon being reduced). This tells me I am at 2200 F or above.

 

The last time I did this I used some low Si, low S cast iron, put it on wrought, left it in the forge for about 1 minute after melting ( this material had a higher viscosity by the way) and folded it several times. It welded just fine (high carbon face to high carbon face) and shows a pattern ( the piece is very small so I do not want to extrapolate too much ), the lines between the high and low carbon are not crisp but gradual and there seems to be a thin much darker line at the original location of the cast iron. I do not know the M.P. of this material, I only use gray cast for that.

 

Jan

Link to post
Share on other sites

thanks for the input on this guys. i had a hard time believing that I was forge welding the cast together, but I had previously heard theat an increase in carbon content will drop the welding temp and since the bits of cast seemed to be sticking together i just wondered if that was the case. being a blacksmith I had just assumed that cast iron was just foul useless rubbish and had left it at that . but the idea using it to make a servicable tool steel seems like tons of fun.

 

 

cheers Jeff

Link to post
Share on other sites

O.k. , so i got a mix of 2 parts wrought to 1 part cast and i welded it up to just over the 1000 layer count today. A rough grind and etch revealed a superfine pattern what appeared to be layers of the wrought and layers of bright white which i am guessing is the cast. Each fold of the 9 was welded then drawn out in one heat. There was no soaking time at the end to allow for carbon migration (yet). I wanted it to be refined to the point where the cast wouldnt just melt and run out.. Before I called it a day I cut a small bit from the billet brought it to critical and quenched it to see what would happen. Nothing. I tried a few other things and got no effect. Now I personally think the reason for this may be that there was infact next to no carbon migration during any of the welds and I just have a billet of cast iron and wrought iron and not anything that you can call steel yet. Or, did I in the process of welding actually fry out so much of the carbon that I have something that its just below the hardening range of steel. Any thoughts on this? Also , if this did make steel would it even be classified as shear steel?

Edited by J. Helmes
Link to post
Share on other sites

There is ALWAYS carbon migration, unless there's a barrier like pure nickel. It doesn't require much of a soak. Something like a minute at welding heat will equalize carbon across thin layers. More than one fold-n-weld and it's homogeneous. Most likely your cast was in the 3% range, and your wrought was less than .2%, and you burned much of it out during the welding.

 

I don't mean to suggest you're not doing something right, it's just the nature of the material. I bet you've got at least .4 % carbon. Did you do a cold water quench? Spark test?

 

And finally, no, technically it's not shear steel, it's something else I don't have a name for. ;) Other than a cool attempt, that is. Keep trying! Maybe you'l get something really neat. B)

Link to post
Share on other sites

thanks alan, i tried it in cold water but to no avail. on the up side of things i have some very potentialy interesting material for fittings. or perhapes if the next billet pans out i can try twisting it up with some of that and seeing what it would look like along the back of a blade. we shall see..

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...