This project aims to study the martensitic transformation in two steels with high potential for application in the nuclear industry: EUROFER-97 and ODS-EUROFER steels. Both steels have very similar chemical compositions, but ODS-EUROFER is strengthened by a dispersion of nanosized yttrium-rich oxide particles. These materials are intended to be used in fission and fusion nuclear plants in the tempered condition. However, peak temperatures during the reactor operation can surpass the austenitizing temperature leading to martensite formation during cooling. We aim to deepen the studies currently in progress (FAPESP Project 2013/19197-9) to determine the influence of metallurgical parameters on the martensitic transformation (austenitizing temperature, soaking time, grain size and cooling rate) regarding crystallographic orientation relationships of the formed martensite and prior austenite. EBSD measurements will be performed on these steels to allow the reconstruction of the parent structures using the software ARPGE. The validation of this software will be obtained by studying a model martensitic alloy (Fe-Ni-C system). Vickers microhardness testing, X-ray diffraction and high-temperature dilatometry measurements will be used as complementary techniques for measuring the hardness of martensite, the fraction of retained austenite and the Ac1, Ac3 and Ms transition temperatures.
News published in Agência FAPESP Newsletter about the scholarship: