Einfluss von Legierungselementen auf die Eigenschaften von niedriglegiertem, warmfestem CrMoV-Schweißgut

Translated title of the contribution: Influence of alloying elements on the properties of low-alloyed creep-resistant CrMoV-weld metal

    Research output: ThesisMaster's Thesis

    Abstract

    The aim of the present master thesis, which was conducted in cooperation with the company voestalpine Böhler Welding, was to examine the influence of the alloying elements Cr, Mo, V and C on the mechanical properties of a creep resistant bainitic 2,25Cr-1Mo-0,25V-weld metal and to define the respective correlations with the microstructure. The evaluation was carried out via a fully factorial 2^4-Design of Experiment (DoE) with two discrete levels for each element. The microstructure of the resulting 16 different welds, produced via stick electrode welding, was examined using light optical microscopy, a scanning electron microscope and a scanning transmission electron microscope and by doing electron backscatter diffraction and high energy X-ray diffraction utilizing synchrotron radiation. The findings of this thesis revealed a more acicular bainitic microstructure and a higher toughness with increasing Cr-content, as well as a higher strength but no influence on the creep behavior with increasing Mo-content. With increasing C-content, the number of carbides and carbonitrides (fine and coarse) rises, which is beneficial for the strength and the creep behavior, whereas the coarse/fine distribution of these carbides and carbonitrides is mainly influenced by the V-content. A higher amount of V leads to less coarse carbides and more fine MX-carbonitrides (M=metal, X=carbon or nitrogen), which are most beneficial for the creep behavior due to their stabilizing effect on the microstructure and dislocation substructure at high temperatures. According to these structure-property relationships, a high V-, medium C- and low Cr- and Mo-content is recommended for producing a weld metal with high creep resistance and balanced strength and toughness. Furthermore, this master thesis showed, that a DoE is a useful statistical tool for evaluating the influence of alloying elements on the mechanical properties and microstructure of a material.
    Translated title of the contributionInfluence of alloying elements on the properties of low-alloyed creep-resistant CrMoV-weld metal
    Original languageGerman
    QualificationDipl.-Ing.
    Awarding Institution
    • Montanuniversität
    Supervisors/Advisors
    • Schnitzer, Ronald, Supervisor (internal)
    • Schönmaier, Hannah, Co-Supervisor (internal)
    Award date8 Apr 2022
    Publication statusPublished - 2022

    Bibliographical note

    embargoed until 31-01-2027

    Keywords

    • structure-property relationships
    • Design of Experiment
    • creep-resistant weld metal
    • 2
    • 25Cr-1Mo-0
    • 25V-steel

    Cite this