Martensitic steels were known for their softening during cyclic tests carried out at high temperature. The softening was at least partially explained by lath and sub-grain boundary elimination. This article was dedicated to an attempt at modelling both phenomena. Thanks to mechanical tests it was shown that the softening was mainly due to a decrease of the back-stress. Transmission electron microscopy permitted a mechanism of low-angle boundary elimination to be proposed. Annihilation between dislocations of low-angle boundaries and incident mobile dislocations was modelled. The macroscopic back-stress was finally computed by using a Hall–Petch law and the Taylor model.

Cyclically Induced Softening Due to Low-Angle Boundary Annihilation in a Martensitic Steel. M.Sauzay, H.Brillet, I.Monnet, M.Mottot, F.Barcelo, B.Fournier, A.Pineau: Materials Science and Engineering A, 2005, 400-401, 241-4