Effects of austenitizing parameters on martensitic transformation and orientation relationships gamma/alpha-prime in ferritic-martensitic steels for nuclear applications

• Grant number: 14/23304-8
• Support type: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): April 01, 2015
• Effective date (End): December 02, 2015
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal researcher: Hugo Ricardo Zschommler Sandim
• Grantee: Kahl Dick Zilnyk
• Home Institution: Escola de Engenharia de Lorena (EEL). Universidade de São Paulo (USP). Lorena , SP, Brazil

Abstract

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.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

ALMEIDA JUNIOR, D. R.; ZILNYK, K. D.; RAABE, D.; SANDIM, H. R. Z.. Reconstructing the austenite parent microstructure of martensitic steels: A case study for reduced-activation Eurofer steels. JOURNAL OF NUCLEAR MATERIALS, v. 516, p. 185-193, APR 1 2019. (14/23304-8, 13/19197-9)

ZILNYK, K. D.; ALMEIDA JUNIOR, D. R.; SANDIM, H. R. Z.; RIOS, P. R.; RAABE, D.. Misorientation distribution between martensite and austenite in Fe-31 wt%Ni-0.01 wt%C. ACTA MATERIALIA, v. 143, p. 227-236, JAN 15 2018. (14/23304-8, 13/19197-9)