Effect of prior austenite grain size refinement by thermal cycling on the microstructural features of as-quenched lath martensite

J. Hidalgo Garcia*, M.J. Santofimia Navarro

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    85 Citations (Scopus)
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    Abstract

    Current trends in steels are focusing on refined martensitic microstructures to obtain high strength and toughness. An interesting manner to reduce the size of martensitic substructure is by reducing the size of the prior austenite grain (PAG). This work analyzes the effect of PAGS refinement by thermal cycling on different microstructural features of as-quenched lath martensite in a 0.3C-1.6Si-3.5Mn (wt pct) steel. The application of thermal cycling is found to lead to a refinement of the martensitic microstructures and to an increase of the density of high misorientation angle boundaries after quenching; these are commonly discussed to be key structural parameters affecting strength. Moreover, results show that as the PAGS is reduced, the volume fraction of retained austenite increases, carbides are refined and the concentration of carbon in solid solution as well as the dislocation density in martensite increase. All these microstructural modifications are related with the manner in which martensite forms from different prior austenite conditions, influenced by the PAGS.

    Original languageEnglish
    Pages (from-to)5288-5301
    Number of pages14
    JournalMetallurgical and Materials Transactions A - Physical Metallurgy and Materials Science
    Volume47
    Issue number11
    DOIs
    Publication statusPublished - 2016

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