Evolution of substructure in low-interstitial martensitic stainless steel during tempering

F. Niessen*, D. Apel, F. Danoix, J. Hald, M. A.J. Somers

*Corresponding author for this work

    Research output: Contribution to journalJournal articleResearchpeer-review

    22 Downloads (Pure)

    Abstract

    The evolution of the substructure and the distribution of interstitial elements in lath martensite during tempering in soft martensitic stainless steel X4CrNiMo16-5-1 was studied with line profile analysis of diffractograms from energy dispersive synchrotron X-ray diffraction, local chemical analysis with atom probe tomography and orientation mapping with electron backscatter and transmission Kikuchi diffraction. Martensite formation occurred below 135 °C without auto-tempering and led to a dislocation density in martensite of 3.8 ∙ 1015 m−2, as determined from X-ray line profile analysis. On tempering, carbon and nitrogen segregated to low-angle and high-angle grain boundaries. Recovery commenced above 550 °C and led to a reduction in dislocation density to a steady value of 4 ∙ 1014 m−2 from 600 to 750 °C. Further tempering led to a second increase in dislocation density at room temperature, owing to the transformation of reverted austenite, formed above 650 °C, into martensite on cooling. It was observed that the recovery of martensite competes with the formation of reverted austenite. The interpretation of the coherently diffracting domain size obtained from X-ray line profile analysis was critically discussed in the context of the internal structure in martensite.

    Original languageEnglish
    Article number110494
    JournalMaterials Characterization
    Volume167
    Number of pages11
    ISSN1044-5803
    DOIs
    Publication statusPublished - 2020

    Keywords

    • Atom probe tomography
    • Lath martensite
    • Micro-segregation
    • Orientation mapping
    • Tempered martensite
    • X-ray line profile analysis

    Fingerprint

    Dive into the research topics of 'Evolution of substructure in low-interstitial martensitic stainless steel during tempering'. Together they form a unique fingerprint.

    Cite this