ANISOTROPIC AND COMPOSITION EFFECTS IN ELASTICPROPERTIES OF POLYCRYSTALLINE METALS

The expressions giving the variations in Young's modulus E and the modulus of rigidity G with direction in cubic single crystals are combined to form the relationship 2/E+1/G=S44+2S11, which is independent of direction for a given crystal providing the effective or mean value of φ = Σ l2m2 (direction cosines) is the same for the two measurements. Experimental measurements for polycrystalline steel have shown that 2/E+1/G is equal to a constant which is also independent of direction, and this result has proved of value in distinguishing between the effects of composition variations which are likely to be obscured by varying degrees of anisotropy. Experimental measurements of Poisson's ratio have also been interpreted.