Thanks for the replies- I think we found a topic of interest. The information comes from several sources, including a renown museum armor reproduction smith in Canada that I am trying to find again, as well as a course I had in engineering on metallurgy. But I should retract and not a few things- this is not a definitive guide, and as Da Bill notes- correctly, armor varied significantly by region and laws, who made it and why did as well. Also its is very true that techniques, laws, practices, and availability varied significantly within what we would consider a local region- but as most populations did not travel far as it was difficult and dangerous, things were far more isolated and evolved far differently. Just think of all the variations of what we think of as English within England itself.
I am really referring to the 14-15th century, England and not at all completely- that would take books, and I am not an expert, but I do consider myself an apprentice armorer, now with a few full sets of plate armor completed for clients. I have done a lot of research, but all sources are not really complete are they? As to references of a knight in shining armor- while I am certain that shining armor did exist, and discounting fashion trends, was written about in reality and as an ideal- outside reflecting the virtue of the inside- a common literary theme of the age, that and damnation. So as I said, everyone is more than entitled to what they believe as its likely as accurate as anyone else.
So the forging process, it is known that with many metals- steel, iron, bronze, and aluminum, that mechanical working of the metal does increase its hardness. By forging on carbon powder or exposure to charcoal, this also adds the ability to bend without deforming or breaking. This was inadvertently discovered across many cultures when forging blades- most notably the Japanese, and in the making of Damascus steel- something encountered during the crusades.
Was all arms and armor made this way- absolutely not. It was time-consuming and expensive, availability of raw materials alone would have prevented this, keep in mind that England was a bit deforested just due to timber being the primary building and heating source- with peat second, and stone and mud following for construction. However, armor was made this way- including the baking in charcoal and in the seeking of ballistic resistant armor (hence why plate was developed in the first place). Combat armor does differ significantly from jousting armor- many sources site this in many countries. It was generally thicker, may have had removable plates for added protection, usually was a bit more “rigid” and was designed primarily for mounted combat. While some may have also doubled as combat armor, a knight given the funds would have surly had “tournament” armor, but again enough examples exist to give either view the ring of truth.
Since I was primarily interested in the metallurgy used, techniques, and methods, I was focusing on what would have been available vs. modern equivalents. I had said that I was not trying to detract from what other know and believe but rather provide additional information to those looking to build a kit and not to discount anything as strictly un-period looking. Chances are almost anything was “period”, even plastics used in the proper design- while materially very far from period- would be close to armor made from bone or horn, or perhaps boiled leather plates. Point is if it existed then, someone would have used it somewhere to make armor in some way.
Also many mercenaries were opportunistic, as were lower knights or man-at-arms, they would scavenge, buy, and acquire weapons anywhere the opportunity arose, some using “ancient” armor as they happened to acquire it, mixed perhaps with leather, studded, chain, or fine gothic pieces. Indeed as uniforms were not provided in general, an army was a motley thing. Uniforms gained prominence as a way of identifying friend from foe, where professional soldiers were employed (no money invested, who cares), but there were few standing professional armies during these times that were in anything resembling a standard uniform, that died with the Romans and was just starting to be developed in fortification guards or royal guards.
So I do apologies as I don’t mean to sound authoritative across such a wide breath of time and regions- .