If you mean composition percentage of steels it is a percentage of Volume lets take for instance the recipe of O1
C) .1.0% Mn) 1.25% Cr) .50% W) .50% V) .20% --- balance is Fe) (Iron)
No matter how massive the batch is, as long as the the steel has a uniform distrobution of these ingrediants, in these percentages, we have O1 Tool Steel. And so to arrive at that we take a container with a known volume. lets say 1000 pound crucible, we add 10 pounds of carbon, 12.5 pounds of Mangenese, 5 pounds of Chromium, 5 pounds of Tungston, 2 pounds of Vanadium, the rest of the container is filled with Iron (or 965.5 pounds of liquid Iron) Mixed well and voila O1 Tool Steel is Born! Hope this helps.
Jason