metals; making, mixing and strengths

Steel is made; it is an alloy of iron. I think it is generally iron and carbon, but that's about the extent of my knowledge. I supposed to method of making it was discovered, so the answer is 'both.' But it wasn't discovered in the sense than an element is discovered.

 

This happens to be a topic I've researched fairly extensively. Though I don't have the time to write a really exhaustive response, here are a couple of great links followed by a summary:

Mining In Middle Ages

SwordMaking

As the above articles will explain, metallurgy had advanced decently far by the middle ages. The various types of iron mentioned by psychotick were well known, and there was an established pattern for producing low-quality iron from its ore (in smelters called bloomeries) and then refining that ore into steel.

Swordsmiths required a very specialized quality of steel with a specific carbon level. Most weapon makers would have known how to judge steel and transform it (either by adding or removing carbon in their own furnaces) into what they need. In some specialized weaponsmithing centers (like Toledo, Spain) there may have been smelters who produced this kind of steel (or close to it) ready-made for the local smithies.

In general, the knowledge of other elements alloyed with steel came and went throughout history and the making of special steels was often a closely guarded secret.

Poor early steels were actually less suitable for weaponry than the most advanced metal of the classical world - that is, bronze. Quality bronzes have properties akin to the steel achievable through ancient means. However, as iron mining became more widespread, the availability of iron made it the preferable metal due to lower cost, and eventually steel making knowledge followed and spread as well.

In any case, read those links. Good stuff in there. Also, further google searches will unearth a great deal of info - just remember to take anything the internet tells you with a grain of salt.