Usage of the small-punch-test for the characterisation of reactor vessel steels in the brittle–ductile transition region

This paper presents a method for the identification of hardening parameters and Weibull-parameters in the brittle and brittle–ductile transition region. A small-punch-test device is developed for hot cells, where a miniaturised disk-like specimen is manufactured and deformed by a spherical punch until failure. Its load–displacement-curve is analysed regarding its information about the material behaviour. Using neural networks, an identification routine is developed, which avoids time-consuming calculations with FEM during an optimisation algorithm. Identified material properties are compared with data from tensile tests. Using the identified hardening parameters, Weibull-parameters are calculated for temperatures at which cleavage fracture occurs.