It was recalled that Frank-Read sources were among the most important mechanisms of dislocation multiplication, and their operation signals the onset of yield in crystals. It was shown that the critical stress required to initiate dislocation production fell dramatically at high-elastic anisotropy; irrespective of the mean shear modulus. It was therefore predicted that the yield stress of crystals would fall dramatically as their anisotropy increased. This behaviour was consistent with the severe plastic softening observed in α-iron and ferritic steels as the α-γ martensitic phase transition was approached; a temperature regime of crucial importance for structural steels designed for use in future nuclear applications.

Frank-Read Sources and the Yield of Anisotropic Cubic Crystals. S.P.Fitzgerald: Philosophical Magazine Letters, 2010, 90[3], 209-18