Microstructure characterisation and mechanical properties of ODS Eurofer steel subject to designed heat treatments

J. Fu*, J. C. Brouwer, R. W.A. Hendrikx, I. M. Richardson, M. J.M. Hermans

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    14 Citations (Scopus)
    103 Downloads (Pure)

    Abstract

    The present work deals with oxide dispersion strengthened (ODS) Eurofer steel fabricated by powder metallurgy involving mechanical alloying and spark plasma sintering. A heat treatment route including normalising and tempering was applied to the as-produced steel, based on differential scanning calorimetry (DSC) measurement. The microstructure was characterised by scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), electrolytic extraction, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermodynamic calculations conducted using Thermo-Calc software were used to determine the precipitation conditions. The results show that the Vickers microhardness of the sample after the designed heat treatment is more uniform compared to the as-produced condition. A dual phase and bimodal microstructure is formed in the as-produced and tempered steels. M23C6 and M6C carbides were found in the as-produced sample while only M23C6 carbides were observed in the tempered sample. The carbides dissolve and reprecipitate during the heat treatment, preferably at the grain boundaries. Nanosized Y2O3 particles were found to be homogenously distributed in the steel matrix, which is crucial for the mechanical properties. The dislocation density in the material is decreased significantly after the normalising and tempering treatment. A yield strength model was developed that includes the strengthening contributions of solid solutes, grain size, dislocation density and nanoparticles. Good agreement is obtained between the experimentally measured and theoretically calculated strength of the as-produced and tempered steels.

    Original languageEnglish
    Article number138568
    Number of pages9
    JournalMaterials Science and Engineering A
    Volume770
    DOIs
    Publication statusPublished - 2020

    Keywords

    • Heat treatment
    • Microstructure
    • Oxide dispersion strengthened steels
    • Powder metallurgy
    • Yield strength modelling

    Fingerprint

    Dive into the research topics of 'Microstructure characterisation and mechanical properties of ODS Eurofer steel subject to designed heat treatments'. Together they form a unique fingerprint.

    Cite this