CHOICE OF EVOLUTION EQUATION FOR INTERNAL-STRESS IN CREEP

The internal stress values in the course of the primary and the steady -state stages of creep in a Fe-3wt.%Si alloy were measured by a techni que analogical to the strain transient dip test technique. Two types o f evolution equation, i.e. phenomenological and derived from dislocati on kinetics, were examined by correlating them with the experimental d ata. in the application of the second group of equations, characterist ics of the real dislocation structure were taken into account. The res ults of structure investigations are discussed in relation to the conc ept of internal stress in both homogeneous and heterogeneous dislocati on structures, in the latter case using the composite model of the dis location structure.