Casting and Forging: Metalworking Scenes

This'll be my first post on here, so let's try this baby out.

Ok so many many novels and stories feature swords, and quite a lot of those have metal working scenes, where these blades are made. What bugs me is when writers describe a process in making a sword or knife, and realistically that blade would fall apart as soon as they tried to use it. So I'll start with Casting vs. Forging

This depends mainly on the blade material, and on the time period. In the Bronze Age setting, it would be made normally of bronze. Just past that, until about the Roman Empire, it would be plain iron. From Augustus onwards, it makes the switch to steel (basically iron, just harder, so it will not dull as easily). 

BRONZE
Bronze is an alloy of a base element copper with tin added in to make it harder. Both of these elements have a low melting point (you can get it pretty easily with a wood fire and bellows) and so they are easy to cast (casting means melting the material and pouring it into a two part mold), which means you can make the object faster, easier, and more detailed than by forging, and you can make many from the same mold. The mold is made of clay, two halves, which have a negative imprint of the blade o the inside. They are tied or pressed together with simple twine. The melted bronze is poured from a clay container called a crucible, into a hole on one side of the mold. The liquid glowing bronze fills up the cavity until it is full, and the mold is left to cool for a few minutes, after which the two halves are taken apart and the now solidified bronze blade is cooled completely in water. It is finished up and sharpened with coarse then fine stones. Often the edges of the blade are hammered on just before sharpening, which work hardens the steel, making it harder to dull. Bronze blades are almond never hammered from bar shape to blade shape. 


IRON/STEEL
Iron and steel are NOT cast. Never ever never never ever. Two reasons: iron has a very high melting point, requiring a lot of work on the bellows and several developments in heat technology, which is why (even though iron ore is more plentiful than either copper or tin) it was not widely used for a long time, when technology developed enough to create the heat required. The second reason, is on the elemental level. The melting then cooling allows the atoms to rearrange themselves to form long, but brittle, crystals inside the iron. These break easily, which means broken blades very very quickly. You remember the scene in Lord of the Rings where the Uruk hai were casting blades? Realistically, the Rohirrim would have had no trouble fending off the horde. That's why cast iron pots and pans are so thick, they are easy and quick to make because of casting, but they will break pretty easily too. 
However it does not take too high of a temperature to forge the steel (heavy forging eliminates these crystals), which is still done very often for strength centered structures. Forging is quite simple, place the iron in the coals, pump the bellows till the steel is red hot, the whack it with a hammer to form it. It's hard to do and takes a while (trust me I know) but it creates a very good blade, and many people (I have yet to read molecular evidence) insist that the forging strengthens the blade. Often to make the blade hard, it is heated up to dull red, and plunged in warm water. This makes the blade fairly brittle though, and in recent times (past two hundred years or so) they found out that heating the blade to about four hundred degrees Fahrenheit will toughen the blade just enough to make it flexible. 

OH, and something I heard of once in a movie. The smith apparently heated up the blade and plunged it into a snow bank. Cooling it quickly like that will harden it, but that much of a shock will crack the blade 99 times out of a hundred. Even warm water will often crack the blade, most modern smiths use oil which cools slower. 



~ Captain Belaq