Varying the amount of alloying elements and the form of their presence in the steel (solute elements, ... What's the “Fe” ?..PAGE:12A.P.F. (Atomic Packing Factor)1. ... Contents of Carbon (wt%)Effect of CarbonCarbon Equivalent (%)= C +Mn/6 +(Cr +Mo +V)/5 +(Ni +Cu)/15 (ASTM