Anybody have the metallurgy specs for common black iron plumbing pipe?

I can't speak for older material, but I have several pieces of new pipe in the shop that I use for various items, and it has "A-36 Hot roll" printed/inked on it. The stuff I have was purchased at a local plumbing specialty shop and ranges in size from 1/2" to 2 1/2" OD.

I don't know for sure what it is, but I use it to make the bowls on my pipe hawks. It doesn't seem to like to forge-weld to itself or anything else. I attach with a threaded stud and safety-silv #56 hard silver solder. I guess it is something like A-36, since it is the same color as and takes patinas the same as the hawk bodies, which I know are A-36. The pipe tends to be more prone to rolling mill flaws, cold shuts, and lamination problems in my experience. If ordinary HR A-36 is crap, the black pipe version is bottom of the barrel :( . It does, however, look good on a pipe hawk, since the striations resemble slag lines in wrought iron ;) .