Another fun fact: Most bolt and fastener makers stamp their metal with their foundry initials or insignia. Bolts also have lines or symbols on their heads that tell you about their material
Like Kent said: When you begin modeling something you end up learning a whole heck of a lot about it. (not that we probably need this level of detail) but I thought it would be fun to share. I deal with this kind of stuff at work when people try to use the wrong material for a job it was not intended for (not my every day cup of tea but we come across it from time to time)..

