Application of track autoradiography method in studying steel recrystallization process

Samples of austenitic steels containing 0.002 to 0.004% boron were irradiated in an EVA reactor with a thermal neutron flux density of 5x1012 cm-2s-1. Cellulose nitrate was used as the track detector for autoradiograms. Boron which delineated austenite grains was mostly present in form of carboborides M23(CB)6 with different level of dispersion. Steel deformation during rolling at higher temperatures (above 1000 degC) took place with complete recrystallization of the austenite. At temperatures of 930 to 940 degC a ''double'' net of grains was observed when it was possible to determine the mutual position of old (after deformation) and new (after heat treatment) grain boundaries. Above this temperature the autoradiograms showed the real structure of the austenite. (E.S.)