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[HAMMERMILL]

I never really understood this distinction between "iron" and "steel" anyways. The terms are interchangable. What does the game mean by Iron and Steel? Impure cast-iron and 20th century stainless steel alloy 1040 or what?

Iron is an element. Steel is an iron alloy with carbon (sometimes other metals) added to it, IIRC, to counteract the brittle nature of straight iron. The carbon is why charcoal/coke is an ingredient in the process, and not just fuel for the fire.

Well duh. So the simple iron objects in the game are made from pure iron, using an advanced smelting tecnique unknown to modern science and steel is so advanced that it introduces carbon into the otherwise pure elemental mixture? I don't think so.

So what does a sword made of pure iron look like in the real world, anyways?

[Bronze Dog]

I didn't say the iron was absolutely 100% free of impurities. It's just relative.

And the steel making techniques of the medieval times typically introduce carbon by spreading it over the surface and folding the ingot in heat. Repeat the process several times, and you've got layers of iron between layers of carbonized iron.

[Skorpion]

I never really understood this distinction between "iron" and "steel" anyways. The terms are interchangable. What does the game mean by Iron and Steel? Impure cast-iron and 20th century stainless steel alloy 1040 or what?

Iron is an element. Steel is an iron alloy with carbon (sometimes other metals) added to it, IIRC, to counteract the brittle nature of straight iron. The carbon is why charcoal/coke is an ingredient in the process, and not just fuel for the fire.

Well duh. So the simple iron objects in the game are made from pure iron, using an advanced smelting tecnique unknown to modern science and steel is so advanced that it introduces carbon into the otherwise pure elemental mixture? I don't think so.

So what does a sword made of pure iron look like in the real world, anyways?

Seriously. Do you know anything about science at all? Steel is what made the modern world possible, and you're assuming it's just interchangeable with iron?

The iron objects in the game are wrought iron. Not 'pure' iron. You don't GET pure iron outside of a foundry. It reacts too well with carbon.
Wrought iron is a low-carbon iron with a bunch of impurities. Easily worked, and is pretty much iron extracted from the rock and worked.
Pig iron is accurately portrayed as an intermediate yet totally useless form of high-carbon iron. Lots of carbon, fewer impurities, but way too brittle to be of use.
Steel is iron with a higher carbon content, and other impurities removed. The carbon settles into crystals, the structure of which can be altered through heating and cooling in various ways. The actual carbon content is important; high carbon content leads to a harder, more brittle steel, while lower carbon content is softer, more flexible and ductile, and will bend rather than just break. As such, harder steels hold and take to sharpening better, but the edge is easily damaged.
The difference is that steel is a lot harder than iron. It's also less prone to rusting. It's stronger, can be worked easily, and the carbon content gives it almost infinite adjustability, and lets you put multiple properties on the same piece of metal. Katanas are a fine example of this; the steel has the same carbon content all the way through, but the back of the blade is softer and less brittle than the sharpened edge, due to cooling at a different rate.

Most importantly, steel can take tension. It can be stressed. The best you can do with iron is add a load of carbon and come out with brittle cast iron, that can be cast into shape and deal with compression, much like stone.
This is the reason why iron bridges are short arches, while modern bridges are tensioned structures with huge spans.

[DangerHelvetica]

So what does a sword made of pure iron look like in the real world, anyways?

Spoiler (click to show/hide)

[Gus Smedstad]

Iron is an element. Steel is an iron alloy with carbon (sometimes other metals) added to it, IIRC, to counteract the brittle nature of straight iron. The carbon is why charcoal/coke is an ingredient in the process, and not just fuel for the fire.

Close.

What Dwarf Fortress calls "iron" is wrought iron, iron with a low carbon content.  It's relatively soft and easy to work.  Pig iron is iron with a very high carbon content, which is hard but brittle.  Steel is iron with a moderate carbon content (typically a bit over 1%).  The iron -> pig iron -> steel process is required because it's pretty much impossible to get that "just right" amount of carbon by smelting iron ore directly.

 - Gus

[CognitiveDissonance]

What does an IRON sword look like? For a simple example, look into history. I know a few obscure facts - for example, Vikings used iron swords; they were problematic because they lost edge very quickly, got rusty, and would get notched easily.
http://en.wikipedia.org/wiki/Viking_sword

Bronze swords were different, as they would hold their edge for longer. They mostly came earlier, and the crossguard designs were less functional. However, those weapons would remain useful for longer
http://en.wikipedia.org/wiki/Bronze_Age_sword

Steel combines the benefits of both, and goes beyond. The most famous historical steel is Roman Empire, early steel work. Are you familiar with the Roman Legionnaires? they commonly used Gladius swords, seen below. Those swords would be sharper, hold edge better, get notched less, not rust as easily. I believe that steel, being less brittle, allowed for higher grade metalwork, and the materials being more common than bronze allowed it to be mass manufactured.
http://en.wikipedia.org/wiki/Gladius

[Gus Smedstad]

snip

Eh, greeked.

If you read much SF, the difficulties of making steel in cultures that have only the vaguest idea of chemistry are a common subject in time travel and alternate-history stories.  The 1632 series talks about it, for example.  Besides the folding method (used in Japan and in "Damascus steel"), there's also things like "blister steel," which involves heating wrought iron in clay pots, and getting a layer of steel around the edges.  It was a slow and error-prone process.  The iron -> pig iron -> steel approach gets used today because it's relatively easy by comparison, you can do it in big batches with consistent results.

 - Gus

[Skorpion]

Blister steel was a very early method of steel production, used before the invention of the blast furnace. It involves lower temperatures, so it's the best they could do way back when.

As for the japanese folding method, that was a method of improving the steel, rather than creating it. The steel itself was similar to the blister steel method, but needed to be folded so many times because japanese iron is, bluntly, shit. Impure, low carbon, hardly any of it.

Damascus steel wasn't just no idea of chemistry, it also involved creating carbon nanotubes in the steel during the forging process, simply through heating it and pounding it with a hammer in the right way.

[Grendus]

Bronze is a good metal, it's no steel (though neither are adamantine) but it makes good armor and weapons and is very easy to make if you have the right conditions. If you embark in a spot with granite near the surface, bronze will be a logical first step. If you embark in a metallically ideal spot (limestone or chalk upper layers), you'll probably go right to steel.

Moreover, iron ores cost 24 embark points and the bars cost 50. Copper Nuggets/Malachite and Cassiterite cost 6 embark points apiece and can be combined with a 10 point charcoal or a 3 point log (or free if you use the ones that make up your wagon) into two bars of bronze. If you increase the amount of bronze you embark with, you can reduce the fuel cost further by bringing Bituminous Coal and processing that with a log. Assuming you use one log, one coal, and one each of cassiterite and copper, two picks would cost you 18 embark points if you forged them yourself, compared to 220 purchased at embark (or 88 if you only brought copper, since if you're buying picks that's probably what you'd get). If you stretch the pick order (let's say you want to forge 6 picks, leaving one dwarf to gather food/farm), you would need 51 points worth of material (using coke instead of another log to process successive bituminous coal saves 3 points) plus a 100 point anvil. Compared to 660 for bronze picks or 264 for copper, that's one heckofa deal, especially since the picks you forge yourself come with quality modifiers if you invested in a weaponsmith. Bronze is the king of embark metals if your mountainhome has access to cassiterite.

[Gus Smedstad]

I've never embarked with metals of any kind.  Usually I'll spend the points on more food and beer to ease the inevitable immigrant waves.  What's happened so far is that I handle early attacks with wooden cage traps, and by the time I need something more I've got steel disc weapon traps.  I'm curious about embark strategies that involve early forging, though, since I've never done that.

 - Gus

[Satarus]

I bring a proficient weaponsmith and a proficient armorsmith.  I also bring an anvil and some iron ore.  That way I can start with picks and axes for my minors and lumberjacks that have a quality modifier.  Embarking on a volcano gives early surface access to magma with little digging or pumping.  By 2nd year, you should have a full blown metal industry churning out steel weapons/armor and metal furniture.

[Grendus]

I bring a proficient weaponsmith and a proficient armorsmith.  I also bring an anvil and some iron ore.  That way I can start with picks and axes for my minors and lumberjacks that have a quality modifier.  Embarking on a volcano gives early surface access to magma with little digging or pumping.  By 2nd year, you should have a full blown metal industry churning out steel weapons/armor and metal furniture.

I assume you are forging steel from the beginning instead of using raw iron, right? Iron is inferior to bronze in both cost and power, the reason it was used both in the game and in the real world is that it's easier to get. But to each his own, I guess.

Each pair of steel bars costs 6 fuel, 2 iron, and 2 flux. Using coal instead of wood for fuel, you could get the cost down to 69 embark points, including an extra coal for forging the picks/axes. It's a fun number, but in terms of embark points it's no 18. You're using 3.6 times the amount of embark points to bring steel for weapons that will see very little combat, when bronze is itself more than battle capable. Unless you immediately pierce the caverns or start duking it out with evil creatures like werewolves and ogres, you don't need steel. Unless you have the extra points, you'd probably be better off with bronze.

To put it in perspective, for the cost, you could bring along roughly enough bronze (I get 7 bars plus fuel, but you can't bring an odd amount of ore) to forge an entire suit of bronze chainmail. That's much better protection than you'd get from a steel pick. Investing the extra points in food, that's 25 meals for every 2 bars of steel if you switched to bronze. That's 51 seeds to be planted. That's 10 pieces of leather for armor, bags, or trade goods. That's 4 threads to be used for sutures, woven into bandages, or sewn into trade goods. You can do a lot with 51 embark points (x3 if you make 6 tools, x4 if you make 7). Food for thought.