On the relationship between uniaxial yield strength and resolved shear stress in polycrystalline materials

Attempts to correlate radiation-induced microstructural changes with change s in mechanical properties rely on a well-established theory to compute the resolved shear stress required to move dislocations through a field of obs tacles. However, this microstructure-based shear stress must be converted t o an equivalent uniaxial tensile stress in order to make comparisons with m echanical property measurements. A review of the radiation effects literatu re indicates that there is some confusion regarding the choice of this conv ersion factor for polycrystalline specimens. Some authors have used values of 1.73 and 2.0, based on an inappropriate application of the von Mises and Tresca yield criteria, respectively. The basic models pertinent to this ar ea of research are reviewed, and it is concluded that the Taylor factor wit h a Value of 3.06 is the correct parameter to apply in such work. (C) 2000 Elsevier Science B.V. All rights reserved.