[M. Mahejdej]

Hello, welcome and excuse me, for I will most probably be asking a question that isn't worth it's own thread.

I'm interested in the difference between "iron" and "steel" arms and their exact meaning.
I always thought that things like iron armour exist only in RPGs, but now that I see this in an article about swords (falchions, to be precise)...:
"They were generally made from iron with steel edges"
...it got me thinking.

What does the author mean by iron? Pig/Cast/wrought/ iron? And is the process of acquiring this form somehow easier or cheaper than acquiring steel (carbon steel? alloy steel?), making it worthwile to use separate materials like this?

Was "iron" armour used? Was it cheaper/ easier to produce than steel armour?

Thanks in advance.
BTW, I came to this forum to learn about the how process of creating arms looked in medieval times, leaving more details about types of weapons and armour for a later time. Nevertheless I must say that it looks like a huge amount of knowledge has been accumulated here

[Dan Dickinson]

Well, someone more knowledgeable in metallurgy should be able to give you a more exact answer.
However, here's just a quick answer. Steel is an alloy of iron and carbon. It's strange that unlike most of history, these days steel is more readily available than plain iron. However, up until the Bessemer process was invented in the 19th century, steel was quite expensive to produce and was thus more valuable. I'm not sure of all the exact details, but the Bessemer process involves blasting the molten steel with a stream of cold air. This allowed steel to be made in large quantities.
Before this steel would have to be made by baking iron in crucibles with charred bones or other sources of carbon. I believe there may have been other ways to manufacture steel, but I can't remember at this point. Therefore, since steel was expensive and hard to produce, methods were used to conserve it. One method would be the one you read about. This method would involve using plain iron for the back and welding the more expensive and harder steel to the edge. This also provided the advantage that the softer iron would absorb shock. Another method used during the early Middle Ages was pattern welding where strips of iron and steel were welded together in various patterns. This allowed the steel and iron to bring their various advantages to the blade: the iron its break-resistance and the steel its strength. As time went on, steel making processes got better and steel became more common. However, iron was still used for items that didn't require the properties of steel. Armour was one of these items. In some items such as maille, iron was an advantage over steel as it would bend under a blow rather than break as the more brittle steel might have . During the latter Middle ages some of the better armour was made with tempered steel although the majority was still iron.
So yes, iron armour certainly did exist. Basically up until the 20th century, most things made with iron were plain iron, not steel.
Hope this helps a little,
Dan

[Jared Smith]

That was a pretty good answer.

Good quality steel has carbon evenly diffused within it. It is relatively homogeneous in terms of mechanical properties. Iron can have much more or less carbon than steel, but that carbon is often precipitated leaving uneven hardness, soft, or excessive hardness.

Blacksmiths throughout medieval era actually had some methods of producing small quantities of what might be compared with tool steel for files and punches. One method was to wrap the iron tool in animal skin. When the skin dried it was encased in a mixture of horse excrement, clay, and sand (sort of a crude crucible.) After this mixture dried it was fired to smelting temperature (the mixture that did not permit carbon from the skin to escape.) Some skins such as goat skin contained enough nitric acid content to create surface carburization effects that actually made decent tools.

[M. Mahejdej]

Ah, thank you both Dan and Jared. I find this method of making tool-steel most interesting :)

I suppose I'll know what to look for now. My biggest mistake was the assumption that "iron" means pure elemental iron and "steel" an alloy of iron and carbon.

Now I'll be researching the smithing process... I suppose I'll look for more sources tomorrow, the biggest question being: were stone molds used to create the basic form of the sword and/or plates for the plate armour?

[Dan Dickinson]

No, I'm afraid that whole Conan sequence with casting the blade blank is a whole lot of movie bunk. In fact I believe that not until some time slightly after the first millennium closed was there a smelting furnace in Europe large enough to make iron molten. In addition, cast iron is brittle and is totally unsuitable for blades. Stone molds were used for bronze, but that is another metal and process entirely. If you wish to know more about the history of iron working Wikipedia has some good articles to begin with.
Hope this was some help,
Dan

[Jeff Pringle]

Many museums and archaeological papers refer to anything ferrous as 'iron,' unless specific analysis was done to that item. So some of the stuff called 'iron' is really steel.

[Don Halter]

A couple years back some friends and I did a tour of several museums and got to handle/measure several items. I noticed "iron" was generraly used how Jeff described. Several armours and weapons did indeed look to be solid wrought iron, but several were pattern welded/composite and were still referred to as "iron".


I absolutely love to make blades from wrought iron with steel forgewelded inbetween for the cutting edge. The coarse wrought iron makes for beautiful designs in the surface.

[Randall Moffett]

Dan,

That part in Conan still makes me laugh. They made copper alloy swords and such like that but with iron it would be very bad for swords and armour.

M.,

I think you will find that many of these processes the develope over time. I think Dan's explination very good to describe iron/steel use. Something to keep in mind is the possibility that some of the early smiths knew they had done something to better the weapon but not why it was better. Another is that just like today fabrication had the best, ok and munitions,economy or just bad quality gear. The best for armour had a top armourer who used better materials and tried to heat treat, the cheapest armour was made of the materials that were cheapest and made it into what was needed with little else done to it. Most armour fits into the ok and economy armour. A look at italian marked armour to non-marked makes this clear in the Knight and the Blast furnace.

RPM

[M. Mahejdej]

Thanks for the info!
I just wanted to make sure that I've got it all right. I'm trying to incorporate as many possible techniques as possible, so some of them are optional.

1. Obtaining the ore. (mining haematite, digging up oregrounds iron, sieving pig iron from a spring).

2. Crushing the mined ore into smaller pieces to remove impurities.

3. Roasting the ore (mostly for hydrated ores like Limonite).

4. The ore is put into a bloomery and mixed with charcoal. The slag melts and gathers at the bottom of the furnace while the bloom (with some remains of slag and charcoal) are left on top and are collected for refining. Limestone was sometimes added as a flux, to decrease the temperature of slag-melting.
(I understand that if a blast furnace was used, the result was pig iron instead, which required decarburization)

5. The bloom is broken into smaller pieces for the removal of any evident impurities.

6. The bloom is welded together by repetitive heating and hammering and the refined (with the same method). Thus, wrought iron is produced, which has a verrrrry low carbon content.

QUESTION: how the hell did they weld two pieces of iron together? I assume that it must have been performed on the anvil. Did they just put a pair of bloom chunks heated to welding temperature on the iron and hammer them while they were close? How come the pieces didn't fall down under the powerful smite? I guess this is a stupid question but I've never seen a smith at work and I'm having problems with imagining it.

7. This is where the smithing process starts. I understand that when a larger piece of wrought iron was formed, the smith shaped it to a basic form of a sword, still heating it and hammering repetitively.

Ok, now what? There are various steps I've heard of, some contradicting the others, I'm not even sure if all of this is true. Can you guys help? I'd also like to know what the proper order is.

A) Further heating and hammering hardens the metal.
B) Heating the blade and leaving it to cool off makes the metal more springy. (?)
C) Heating the blade and then putting it into oil hardens the blade.
D) Selective hardening by heating the blade and cutting a pile of wet (cold) dirt with it. This way only the blade is hardened, leaving the rest of the blade springy.
E) Forgewelding steel on the blade. Again, how exactly does this work? Did they melt the steel?

Many thanks for your interesting input, friends

[Kjell Magnusson]

Some thoughts on different points:

2: Crushing the material will also increase the reaction rate in the furnace (compare with how sugar powder dissolves faster than sugar cubes). In order to remove the rock from the ore you would also need some kind of sorting stage after the crushing.

A: The hammering and heating in itself will most likely not harden the material. Turning the soft iron into harder steel (by adding carbon, obviously) would probably be done in a separate step (called carburisation), if I've gotten the right idea at least. basically, one heats the material in a very carbon rich environment, causing carbon to diffuse into the material. Normal forging, which often means keeping very hot material in the open atmosphere, would probably be more likely to decarburise the material. However, this step (as well as the hot working of the bloom earlier) can hep remove impurities, and homogenise the chemical composition, both of which increase the quality of the material.

B: When done with a slow enough cooling (and on it's own, see the next point), it makes the metal softer and less brittle. It removes work hardening as well as any hardening due to thermal cycling (if any).

C: Yup. Now, after this stage, one could heat the blade a bit, and then let it cool. This is called tempering, and would be the heating part that makes blades "more springy. What it does is that you sacrifice a little bit of hardness to remove the worst of the brittleness form the hardening, resulting in a "springy" blade (relatively so at least).

D: I've never heard of this method for differential hardening before. I have heard of methods though where the blade is first coated in a clay layer of varying thickness, heated, and quenched. The parts with the thicker layer cool slower, and are left more or less unhardened (this is the traditional Japanese way for example). One could also do a selective tempering to get a similar effect, by heating some parts of the blade more than others during the tempering.

As for welding (pattern welding or otherwise), I think the "Confessions of a bladesmith! Secrets revealed!" topic over at swordforum might be a good read: http://forums.swordforum.com/showthread.php?t=13809
But, basically, it seems that the idea is to heat the two pieces, put some flux on the surfaces, put them together, and then hammer them together. The fact that nature likes to get rid of surfaces means that you can then get the two pieces to join together without having to melt anything. The same principle is used in the process known as sintering (where an item made from powder that has been pressed together is heated to a temperature below the melting point, the powder particles still bond together to a single, if often porous, piece).

There, hopefully it'll be decipherable...

[M. Mahejdej]

That's quite an interesting reading, thank you!

One more thing: the carburization process could be performed on the source material (in a stone crucible) - resulting in a steel ingot, that was then worked into a blade, or on the blade itself. However, Kevin's article mentions drawing the form up to around 6 feet during the process- could this be done with wrought iron? Or did making a two-handed sword require the use of steel from the beginning (ruling out that forgewelding technique)?

[Jared Smith]