Multiscale in-situ observations of the micro- and nanostructure of a PH 13-8 Mo maraging steel during austenitization

Andreas Rosenauer, Dominik Brandl, Gerald Ressel, Thomas Hönigmann, Manfred Stadler, Christoph Turk, Christoph Gammer, Manfred Wiessner, Ernst Gamsjäger, Martin Stockinger, Ronald Schnitzer

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Abstract

The aim of the present work is to elaborate on the microstructural evolution of a PH 13-8 Mo maraging steel during austenitization by using multiscale in-situ techniques, which range from high-temperature electron backscatter diffraction and high-energy X-ray diffraction to high-temperature transmission electron microscopy. In order to supplement these in-situ experiments, samples quenched from different temperatures after isochronal heating are subjected to an in-depth microstructural characterization by means of atom probe tomography. The results indicate diffusion-dominated kinetics for the α’ to γ transformation in the investigated heating rate range. Moreover, high-temperature electron backscatter diffraction experiments confirm the occurrence of the austenite memory effect. In addition to the inheritance of grain size and crystallographic orientation of the prior austenite grains, a lath-like substructure remains in austenite, which consists of thermally stable, geometrically necessary dislocations. It is suggested that these dislocations play the key role for enabling recrystallization at higher temperatures without prior cold deformation. This phenomenon is evidenced for the first time in a PH 13-8 Mo maraging steel. However, it is believed that excessive amounts of carbides at austenite grain boundaries or an alteration of the dislocation structure could impede this abnormal recrystallization.

Original languageEnglish
Article number113554
Pages (from-to)1-13
JournalMaterials characterization
Volume2024
Issue number208
DOIs
Publication statusPublished - Feb 2024

Bibliographical note

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Keywords

  • In-situ electron backscatter diffraction
  • In-situ high-energy X-ray diffraction
  • In-situ transmission electron microscopy
  • Maraging steel
  • Phase transformation
  • Recrystallization

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