Methods of Making Chain Mail (14th to 18th Centuries): A Metallographic Note
Author(s): Cyril Stanley Smith
Source: Technology and Culture, Vol. 1, No. 1 (Winter, 1959), pp. 60-67
It is a somewhat complex paper, made more so by the fact he examined maille from Germany in the 16th century right up to 18th century Turkish examples.
The take home message is that most of it was in fact made of soft wrought iron, which would indeed be drawable, and he says that all examples were made by drawn wire. All had also been annealed after drawing, but many had also been hammered somewhat flat, and many of the shirts examined had hammer welded rings amongst the riveted.
A 14th century coif had round wire, and one German shirt from around 1525 had been drawn, flattened and quenched and tempered. Therefore its rings were much harder than the other shirts, which would make them stronger but also a little more brittle.
The tricky question then is, what treatment did the majority of shirts recieve? Tempering and quenching would increase the strength enormously, meaning that arrows or sword points may well not pierce the rings, but I cannot tell for sure, and of course soft iron rings may have their own advantages in terms of absorbing impact by distorting. The poor preservation of many examples of mailled makes it hard to examine their metallurgy, moreover it is perfectly possible for there to have been changes in manufacturing methods and styles over the medieval period, such that I do not like taking examinations of shirts form the 16th century at face value, especially when Smith's examination only includes one from before 1500.
Suffice to say, a great deal more work needs to be done.
Ideally what I need is a workshop to make me a number of different types of maille, in various ways, and temper some and not others. Then we take the types and subject them to various forces, from sword blows to arrows, and see what happens. I'm not sure how much it would cost, anyone got 10k to begin with?