We like metals. They're useful. They allow us to do a lot of things, like download porn on the internet, and kill people a lot easier.

Most of them, however, can't be found in a useful form. I can't go take a walk in the woods and find parts for my 1989 Ford Tempo. Instead, metals are usually found stuck in rocks. Damnit!

Metallurgy is the science of getting metal out of those rocks and turning it into something useful.

Starting about 6000 B.C., humans first started working with metals. Or a metal, to be specific. They began making pretty decorations with Gold. They started off with Gold because it's all shiny, and you could find pure veins of it in rock, without having to get it out of ore.

Of course, it's soft as hell, much too mallable to make anything useful out of! At least, not till electronics came around. But, since it's a noble metal, it's all shiny and stays that way. So we kept on using it to make us feel pretty and convince us that we're better than damned dirty apes.

Basically the same story for silver.

Around 4300 B.C. people began to figure out how to make simple tools from copper. We guess that some potters in West Asia dropped some Malachite into their clay firing furnace, and lo and behold, they got copper from the rock.

Once people figured out that you can get metals from rocks, things took off. The next major change came in 2500 B.C. when some Sumerians figured out that if they mix this ore with that ore before smelting it, they get a stronger, easier to work with metal. They had invented the first alloy, Bronze, which is made from Tin and Copper.

Cool huh? Bronze rocked because it made far better weapons and tools than just copper on its own. You know, cuz it's harder. And it's shiny!. And the next major change was... IRON!

IRON! IRON! IRON! Iron is strong. Strength crushes enemies. IRON!

And boy did Iron ever crush enemies. It made the swords that were least likely to break, the axe-heads that were least likely to shatter, armour that could deflect the hardest blows.

It also made the best tools. Scythes, Plows, etc. However, there was one small problem. It was expensive as heck. People first got Iron from the remains of meteorites, however there wasn't enough there to apply to anything useful. The first commercial source of iron was an oxide called Haematite. To reduce it to iron, you needed to blast it at temperatures above 1100 C. This was pretty tough to do when people first started producing it, about 1400 B.C., and as a result it was about 5 times as expensive as gold.

Iron was first reduced from ore by the Hittite Kingdom. They did quite well with the funky new weapons they made, and were able to expand their borders. Knowledge of ironworking spread from there, hitting India sometime in the latter days of the 2nd millennium B.C., and to Greece and other parts of the Mediterranean by the turn of the millennium.

Technology progressed, as it is wont to do. Iron became cheaper. First, we started off with wrought iron. Steel is strong. We learned how to temper it, to make it turn out just the way we like it. No, not too hard, just right. Back in the day, the coolest steel was Damascus Steel, as some swords made there were strong, extremely flexible, and held the sharpest edge.

Fast forward s'more. Damn, we got all kinds of funky stuff. Titanium alloys for our bikes and our space shuttles. Gold plating, Aluminium cans, planes, trains and automobiles. Stainless steel, platinum catalytic converters, bronze plated baby shoes.

Metallurgy, a subset of Materials Science, traditionally deals with taking ore and turning it into something useful.

The ore, once mined, is smelted. Basically, they crush up the ore, stick it into a big furnace, and if the conditions are right, they get themselves some liquid metal.

Of course, there's the minor problem that crops up when the ore isn't pure. This happens a lot. Often times a silicate flux is used to concentrate the impurities for later removal.

Of course, depending on exactly what's in the mix, they just might use it. Because alloys are our friends!

Mix up a batch with the ingredients you need, what's the next step? Pour it into a container and cool it! Just like making ice cubes!

Well, not exactly. The next step is to get it into the shape that you want, and then apply a heat treatment that gives it the properties that you want.

For example, if you're making a sword, you take a piece of steel, heat it up and hammer it into sword shape, and then stick it in a bucket of water.

Above 727 C, Steel is stable in a crystaline structure form called Austenite. When you cool it down, it changes form. However, exactly what it changes into depends on how fast you cool it down. If you cool it slowly, it will turn into Pearlite. If you cool it a bit quicker, you get Banite. If you're able to cool it really quickly, dropping down to below 500 C within a second, you can form 100% Martensite.

This can be accomplished by sticking a hunk of hot steel into a barrel of water. Ok, so we've got a hunk of mostly Martensite. Martensite is strong, strong like bull. But it's also very very brittle, and quite useless for any actual application. So what do we do then? We temper it!

This is done by heating it up again, not quite at hot as before. Usually between 300 and 650 C. It's kept there for a while, enough time for some of the Martensite crystals to reform, turning the hunk of metal into Cementite in a Ferrite matrix!

Simple! Child's Play!

Sounds complicated, eh? That's because it is. Anyways, the end result is something that's nearly as strong as Martensite, but is a hell of a lot more flexible and ductile.

So how do you get to make other stuff? Well, mix it up, pour it into a container, and bake it. Really, pretty much everything is as complicated as the above process, if not more. So let's turn this into the...

Metallurgy Metanode!

William D. Callister, Jr. Materials Science and Engineering An Introduction 5th Edition, John Wiley & Sons, Inc., 2000.

Met"al*lur`gy (?), n. [F. m'etallurgie, fr. L. metallum metal, Gr. a mine + the root of work. See Metal, and Work.]

The art of working metals, comprehending the whole process of separating them from other matters in the ore, smelting, refining, and parting them; sometimes, in a narrower sense, only the process of extracting metals from their ores.


© Webster 1913.

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