Microstructural, chemical, and crystallographic investigations of dynamic strain‐induced ferrite in a microalloyed QT steel

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Organisational units

External Organisational units

  • Voestalpine Wire Rod Austria GmbH
  • voestalpine Stahl Donawitz GmbH
  • voestalpine Forschungsservicegesellschaft Donawitz GmbH

Abstract

Dynamic strain-induced transformation (DSIT) enables the formation of fine-grained ferritic microstructures, which are well suited for cold forming processes in the as-rolled condition. In this work, the formation mechanism, chemical composition, and crystallographic orientation of DSIT ferrite were investigated in a micro-alloyed steel and compared to pre-eutectoid ferrite. High-resolution techniques, such as scanning transmission electron microscopy and atom probe tomography (APT), were used for the investigations. To generate DSIT ferrite and pre-eutectoid ferrite, different experimental routes were applied using a compression deformation dilatometer. The results show a large number of NbC precipitates within DSIT ferrite, and show that the formation of DSIT ferrite is accompanied with C diffusion and the formation of retained austenite. APT measurements revealed that the C- and Mn concentration in DSIT ferrite is higher compared to pre-eutectoid ferrite. The crystallographic orientation of DSIT ferrite was examined using electron backscatter diffraction. The crystallographic orientation of DSIT ferrite after the deformation route revealed that the <111> plane normals are parallel to the compression direction with the <110> directions pointing towards the radial direction of the compressed sample. The results suggest that the formation of DSIT ferrite is a displacive mechanism, accompanied by C diffusion.

Details

Original languageEnglish
Article number313
Number of pages14
JournalMaterials
Volume12.2022
Issue number2
DOIs
Publication statusPublished - 10 Feb 2022