Study of fracture mechanisms at cyclic fatigue of steels used in nuclear reactors I

This study deals with the possible reasons of nucleation and propagation of macrocracks, mesocracks, and microcracks in stainless austenitic steels after low-cycle fatigue tests at room temperature. It is shown that macrocracks in these steels are formed only after completion of 20-30% of cycles of total deformation. Statistical analysis showed that the average length of slip bands and that of microcomponents of a macrocrack are equal, and they are always parallel to each other, that indicates their crystallographic character. Macrocracks preferably propagate through the grains with no apparent signs of plastic deformation and through isolated mesocracks, but not through mesocracks and grain boundaries. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)