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Working on a project for a paying customer, thought you all might enjoy a few pictures.

 

Carburizing cannister

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Blister steel (med carbon content)

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Kerry was kind enough to let me use his forge and hammer

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That chunk started life as 12 strips of carburized wrought iron

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Due Date is Christmas, so I'll be sure to be sharing more in the next couple weeks.

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Awesome, I wanna try that some day. I've never been able to find a chunk to play with, making it's the only way to get it...

 

How many folds do you plan? Wonder what alloying elements such a blade would have, would manganese be likely from carbonized wrought? I look forward to seeing what you make of it....(I vote early coffin hilt bowie, or sax)

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Nice project, thanks for sharing. Pardon my ingnorace but what causes the "blisters"?

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istory » Primary steelmaking » Blister steel

 

In order to convert wrought iron into steel—that is, increase the carbon content—a carburization process was used. Iron billets were heated with charcoal in sealed clay pots that were placed in large bottle-shaped kilns holding about 10 to 14 tons of metal and about 2 tons of charcoal. When the kiln was heated, carbon from the charcoal diffused into the iron. In an attempt to achieve homogeneity, the initial product was removed from the kiln, forged, and again reheated with charcoal in the kiln. During the reheating process, carbon monoxide gas was formed internally at the nonmetallic inclusions; as a result, blisters formed on the steel surface—hence the term blister steel to describe the product. This process spread widely throughout Europe, where the best blister steel was made with Swedish wrought iron. One common steel product was weapons. To make a good sword, the carburizing, hammering, and carburizing processes had to be repeated about 20 times before the steel was finally quenched and tempered and made ready for service. Thus, the material was not cheap.

 

Britannica Encyclopedia online! I was curious too

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Wow. Lots of questions, I though this was well-known by now.

 

One of the reasons I like Shear Steel, is that it has all the properties of Wrought Iron, except with carbon so it'll harden. No alloys, so it is still a "simple steel" with a bit of slag inclusion (silica trapped in the matrix). Multiple hammerings at welding heat will remove most of those inclusions, though.

 

The blade I'm making is a Gladius, and I had two batches of blister to work with. The core steel didn't get quite as much carbon, and is a lower grade wrought to start with. That's what you see in the picture above, and it was folded probably 3 times after the strips were welded up together. The jacket steel, which was wrapped around the edge, was made of 5 strips of a better wrought iron, and is the blister steel pictured above. That stuff welds and forges like butter. I love it.

 

Propeine's explanation is a decent description of the Sheffield process for making Shear Steel, but it can be done in small batches like this, as well. Each additional folding increases the refinement, removal of slag, and homoginization of carbon. Back in the day, you could by raw blister steel, shear steel, double refined shear steel, and for a bunch of money, triple refined shear steel...the best being reserved for high-tech application like razors, lower qualities used for ax bits and kitchen knives.

 

And that foot armor is something that Kerry had, and threw on my leg when my jeans caught on fire from hot flux.

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One of the reasons I like Shear Steel, is that it has all the properties of Wrought Iron, except with carbon so it'll harden. No alloys, so it is still a "simple steel" with a bit of slag inclusion (silica trapped in the matrix). Multiple hammerings at welding heat will remove most of those inclusions, though.

A very simple steel indeed. I wasn't sure what might have been present in the wrought other than a bit of silica. It will be very interesting, as all modern steel has manganese to some extent. I would think it will be a very shallow hardening steel, once finished. Sounds perfect for differential hardening.

 

A gladius, you say.... this is gonna be good.

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I think Grainger carries the foot/leg cover in their protective equipment section...pretty sure I saw it in their catalog recently. Chris you are one of my metal heroes :)

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Hi Chris,

What did you use in the can with the wrought iron to carburize it?

I've done it with powdered charcoal and it worked great... just takes heat and time.

 

Didnt you get any pics of the flaming pants dance you most likely did when your pants leg was on fire?.... geee, the good stuff always gets left out LOL

 

Randy

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Heh, Randy, actually Kerry looked at me, and said "Hey, your jeans are on fire." I said "oh, I guess they are." Patted them out, and went back to work, while Kerry went and got the shield and strapped it on as I was still hammering. I only fear the fire when it gets close to my beard. :P

 

Also, I believe it was Park Metallurgical #21, Ric Furrer sent me a box from his 50-gal can. Ric, of course, doesn't do anything small.

 

Peter, what I found with this batch, is that the better quality the wrought, the better the Shear steel will be. The stuff I used for the edge-wrap came from Thomas Powers' pile from the Ohio state penitentary water tower, and the bar it made was just perfect... forges like butter, super-clean, and blistered better than the stuff I used for the core steel.

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Pretty much any foundry supply should have legings like that.

 

No idea what they cost, but would certainly be worth it

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I should have worn those when I was welding (stick welding not forge welding). Had a warm feeling on my leg. Had my helmet down didn't think much of it. Pretty soon it was a bit more than warm. I had highwaters after that and no damn leg hair up to my knee. On another note in college we wore entire suits like that when we were doing foundry work.

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Way to go, Chris! You da man. B) I'm jealous. :P

 

As for alloying elements in wrought iron, depends on the ore, the flux used in smelting (if any), and the fuel used to smelt.

 

Some of the ores around here are high enough in manganese they were used for manganese ore after the iron industry dried up. :ph34r: Phosphorus is very common, and if coke was used in the smelt sulfur is likely as well. Charcoal has stuff in it as well, including boron and vanadium IF the tree grew in an environment rich in said elements.

 

The moral: wrought iron is almost never pure iron and silica. It usually runs about .18 - .25% carbon as well, if smelted in a bloomery. Wrought produced via indirect methods like puddling will usually be lower in carbon due to the nature of the process, i.e. more oxygen blown across it burns out the carbon while the pig iron is still in liquid form.

 

A former state geologist of Tennessee once wrote a report for the EPA using iron ore elemental analysis to prove that a fish kill was not the result of natural processes as local industry claimed. Trace amounts of almost everything in the periodic table were found in the ore, but none of the chromate of mercury that was responsible for the dead fish. Gotta watch those electroplaters and rayon factories, you know!

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