There is a ton of raw materials data in the raw charts below that can help answer some of your questions about how/why to choose one material over another, but it's in a format most appropriate to the more engineering-savy folx out there. Raw data is in the first tables listed below, followed by some additional discussion of the implications of that data afterword. Please use the back button on your browser to return to the materials discussion when you're finished here.
So What does all this data mean?
In short. . . it means the same thing that the summaries on material selections say on the previous page. . . *grin*. . . but anyway. . .
You can draw several conclusions from this data, some of them are listed below:
You'll note that the brinell hardness of TI is more than 2x that of any other available material. This means that it is highly resistant to being scratched, while the aluminums are the softest on the list and therefore the most easily scratched.
You'll note the obscenely-high tensil strength of the Titanium, from this you can safely draw the conclusion that this is an extremely difficul material to tear/break/dent/shape. . . BUT . . . you'll also notice the low modulus of elasticity. . . this means that it will bend/flex on impact MORE easily than steel. It won't stay in that bent shape (dent) because of the high tensil strength. . . but it will flex. . . hence, more felt impact in some instances.
You'll note that in terms of pure material weight measures, Aluminum is the lightest choice. . . but when you factor in the strength of the material, and therefore the thickness of the material that's needed to be safe. . . Titanium becomes the lightest choice.
A comparison to actual Medieval Armour Finds
When trying to utilize armour to re-create elements of medieval times, in a modern combat setting with modern safety sensibilities. There are two discretely different schools of thought. The common wisdom is that (as an example, SCA style combat) the most historically authentic choice of materials for armour is a mild steel, like the commonly available 1018 steel. This is an example of trying to recreate the materials, but not necessarily the FUNCTION of a medieval harness. The other school of thought is that the material choices are less important than having an authentic weight/function of the piece of armour in question (so long as the appearance is appropriate). This is the position that I support, by the way *smile*. An example/illustration follows:
A properly tempered piece of medieval armour is very similar in weight on a cubic-inch to cubic inch basis to modern steel. The major difference that most people overlook is the difference in -thickness- of the metal that the armour is made up of.
A medieval arm harnesses (just to pick a single example) from the mid 1400s measure out at about .030-.035" in thickness (we're talking 22 guage metal here. This was not that big of a deal to a medieval warrior who was much more concerned about not being CUT than he was about having that piece of armour significantly deformed and requiring significant repairs after each battle.
By comparison, a similar SCA arm harness is likely to be 16 guage mild steel. This means that the medieval harness (assuming that there is approximately 2 square feet of metal in an arm) weighs in at 3.04 lbs, while the SCA arm harness (to meet our modern requirements for safety and durability) weighs in at 6.3 lbs. . . more than 2x the weight of its historical counterpart.
This is why I like titanium as a material (despite it being such a colossal pain in the *** to work with) 6al-4V titanium weighs in at about 58% of the weight of mild steel, while being -significantly- stronger. This allows that same 2square foot arm harness to be constructed out of 18 guage TI, and come in at a weight of 2.91 lbs. Much more similar in weight (FUNCTION) to its medieval counterpart, while still meeting our modern requirements for safety and durability.
