Sunday, June 20, 2010

Working Meteor Iron?

I received a request about a possible commission to forge some meteor iron into a blade. I took the trouble to expand to detail on the response, with the full intent of sharing my opinions with my larger block of readers.

Here’s some of the difficulty of the piece…rather finding someone willing to forge it. My client wishes to use meteorite iron he acquired from an impact site in the states. Additionally he has floated the idea of using some volcanic ash in the forging or differential hardening of the blade. The piece that he wants is a conceptual art piece as much as a collectable show piece. The underlying theme of the piece will be “extinction”. I’ve come across a few suppliers in which knife makers use to buy stock metal that do have pattern forged steel using meteor iron but finding a small forge willing to use the iron he has or having experience enough to do so has been a little difficult so far.

Calvin - BadAss Jewellery

Here's the background:

1) Meteor Iron

The stuff is notoriously difficult to work with.

Merely getting a piece of meteor is not exactly easy - or cheap. As metal, it is sold by the gram, like silver. I do have a small slab of very high quality meteor iron, in the form of a cut and polished slab of metal. I got it from a jewellery supplier (now lost) maybe 15 years back. The piece is about 4 x 6 cm, about 3 mm thick. At the time it cost me roughly $100 US. I have no real idea what complete meteors of suitable size might cost. I'd estimate you would require a piece of raw meteor something between a golf ball and a tennis ball in size.
Individual complete meteors vary *extremely* in quality. Most are not suitable for forging, the mere process of heating and plunging through the earth's atmosphere doing nasty things to both the quality of the alloy and also tending to fracture the structure.
The reason any smiths you have talked to have mentioned layered steel with meteor as a component is that the best way to successfully end up with a workable blade is to incorporate the meteor iron into a matrix with other iron alloys to help hold the meteor together.

Image - The slab of meteor iron from Africa (Keyna?) The source was a huge ancient strike, large enough to be mined as metal. The dark spots are inclusions, note the stress cracks at the upper right. The metal has been polished and lightly etched for use as a jewellery material.

Meteor iron is extremely high in nickel content. To the tune of 7 - 15 % Nickel. Modern stainless steels are in the range of 0.5 to maybe 2%. Nickel is extremely hard to forge - the metal resists forming, even at forging temperatures. So a pure meteor, assuming it was not full of cracks and flaws to begin with, would be much more difficult to forge out than even modern alloy steels.

A meteor is made up of nickel and iron. No carbon what so ever. Carbon is what makes a blade hard, which is what allows it to keep a sharp edge. Although the rigid nature of the high nickel content would help this some, again a pure meteor blade would just not hold an edge like a simple carbon steel would. So once again, bladesmiths who are concerned with the qualities of a working knife will incorporate high carbon steels into the matrix with the meteor iron to provide something like correct edge holding. The customer needs to decide if they are expecting a piece of jewellery - or a working tool.

Nickel has a real attraction for sulphur, especially at welding temperatures. Sulphur 'spoils' the weld, if not keeping it from correctly fusing, it can make the result brittle. And working with straight meteor is more likely to require continual welding steps to correct for the tendency to fracture. The rigid nature of the nickel also means that the metal needs to be forged into the higher temperature ranges (At the normal orange, this stuff is so stiff it hardly moves under the hammer). Ideally the working forge would be a high end propane forge to try to eliminate the sulphur. Working against this is how much easier it is to control the correct working atmosphere (oxygen balance) required for successful welding in a coal forge. Again, the simplest way to prevent these specific problems is cover the nickel alloy with slabs of mild steel, so layered steel again.

Compared to some of the other problems, handing the material may seem trivial. But the frustration of trying to work up something from an irregular 'rock' is not to be discounted. I would expect you would end up spending more time chasing the hot piece as its bounces off the anvil than actually hammering it (based on admittedly limited past experience).

2) Volcanic Ash

I am not sure that there would be any utility to be provided here.
Ash is used in the annealing phase. In short, the longer the blade takes to cool, the softer it becomes for shaping, and most importantly, the more internal stresses are released. So the ideal annealing material would be an extremely good insulator. Wood ash is the normal material of choice, sometimes people use vermiculite. I have never had a sample of 'volcanic ash' to examine. I expect the material, given its source, may in fact *not* be an ideal insulator.
For your customer, it might be possible to build a steel box, fill that with the volcanic ash, then heat the whole thing. Insert the hot blade blank, then bury the whole box into a fire, let the fire cool naturally. The bulk of the wood fire around the box would provide the technically required slow heating. This is a lot of extra trouble just for a 'concept'.

The most obvious application of volcanic materials might lay in the polishing steps. I believe both pumice stone and powdered ash are used as abrasives in the Japanese traditions. I don't work with those methods myself. They are hand methods and time intensive (read expensive labour).

The various initial forging and manipulation problems are similar to those I experience when working iron blooms down into working bars. Although I certainly would not say I have the best experience with this (Lee Sauder is certainly the master there). I certainly have more than almost any Canadian blacksmith. (This not so much because I am so wonderfully skilled - more like no one else is that crazy.)

I have twice attempted to work up complete small nickel iron meteors into finished bars. In both cases, the material was provided by the client, pieces roughly the size of a half walnut (and about the same shape). Extremely difficult to manipulate something that small! Both times, the material completely disintegrated due to stress cracks and inclusions. The first time, I just gave up on the process the fragmentation was so bad. The second time I did what most everyone else does, which is layer the meteor material between pieces of modern steel. I was then able to create a billet of material with the meteor as one of several layers and finish the project.

The overall problem with the scope of the project is that there are just too many variables on the materials end to be able to quote a simple price. The whole forging process itself would be one giant experiment. This leaves you with two possibilities:
1) You find someone who has already developed working experience specifically with forging blades from solid meteor iron. The cost of a commission is going to reflect all the past effort to develop those skills.
2) You fund the experiment. This may mean covering the cost of several attempts before a product of the desired quality is the result

I would expect the raw materials to run several hundred dollars.
I would estimate the time expended would run at least a full working week. Ball park for that block of *my* time is $1000.

There are good technical reasons why most experienced bladesmiths are only offering meteor iron incorporated into layered steel billets - rather than pure meteor iron blades.


Steve Muhlberger said...

Your pricing sounds cheap to me!

Anonymous said...

I've just comissioned a pure meteorite blade - I provided a 800g nantan specimen. It split in two the moment it was struck but the smith was able to produce a 7 inch blade using one of them ( the other piece went to him to offset the cost). It's produced and extremely hard blade, the biggest suprise was that the Widmanst├Ątten patterns have come through like wootz.

Anonymous said...

There is a national park (I forget the unpronouncable name) in southern Sweden, which is a huge iron mountain jutting up steeply from the normal landscape.

This mountain must be world's biggest meteorite (though one big as a small car in Namabia claims this honor).

I was told when I visited this Swedish park that from before the middle ages until the early 20th century iron cooking pots, axes, etc. had been made from iron taken from this site. I am guessing this meteorite must not have had so much nickel in it ? It is now against the law to remove any stones from this park.

R Wenner in Cheshire, UK

Anonymous said...

The swedish meteorite could be Muonionalusta. The meteorite in Namibia would be the Gibeon meteorite.


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