to determine some average orientation factor M̅ . The best estimate for an fcc lattice is M̅ = 3.1,obtained by G. I. Taylor based the use of the von mises compatibility condition and assuming thal all grains undergo the same deformation as the overall deformation . The energy expended in deforming a polycrystsl must be equal to the sum of the increment of work performed on each of the n slip systems.