TY - JOUR

T1 - Multiscale in-situ observations of the micro- and nanostructure of a PH 13-8 Mo maraging steel during austenitization

AU - Rosenauer, Andreas

AU - Brandl, Dominik

AU - Ressel, Gerald

AU - Hönigmann, Thomas

AU - Stadler, Manfred

AU - Turk, Christoph

AU - Gammer, Christoph

AU - Wiessner, Manfred

AU - Gamsjäger, Ernst

AU - Stockinger, Martin

AU - Schnitzer, Ronald

N1 - Publisher Copyright: © 2023 The Authors

PY - 2024/2

Y1 - 2024/2

N2 - 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.

AB - 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.

KW - In-situ electron backscatter diffraction

KW - In-situ high-energy X-ray diffraction

KW - In-situ transmission electron microscopy

KW - Maraging steel

KW - Phase transformation

KW - Recrystallization

UR - http://www.scopus.com/inward/record.url?scp=85181961751&partnerID=8YFLogxK

U2 - 10.1016/j.matchar.2023.113554

DO - 10.1016/j.matchar.2023.113554

M3 - Article

VL - 208.2024

JO - Materials characterization

JF - Materials characterization

SN - 1044-5803

IS - February

M1 - 113554

ER -