The role of austenite twins on variant selection during decomposition in low carbon steels

Fuente: arXiv
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Auteurs principaux: Birch, Ruth M., Britton, Ben, Poole, Warren J
Format: Preprint
Publié: 2026
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author Birch, Ruth M.
Britton, Ben
Poole, Warren J
author_facet Birch, Ruth M.
Britton, Ben
Poole, Warren J
contents Thermomechanical Controlled Processing (TMCP) is widely used to control the microstructure and properties of linepipe or high strength low alloy steels (HSLA). These steels are often joined by welding and used in demanding environments such as the Arctic. In these materials, the thermal path the steel experiences is critical for understanding microstructural evolution during processing. A key step is the solid-state phase transformation during cooling from the high-temperature austenite to the room-temperature microstructure which significantly influences the final mechanical properties. Specifically, the population of different variants and grain shapes that form affect the types and morphology of the grains, and grain boundary network which influence strength and toughness of the final component. In this paper, we apply 3D microscopy using a Xe-plasma focussed ion beam scanning electron microscope (pFIB-SEM) which is equipped with electron backscatter diffraction (EBSD) in a static configuration to characterize the room temperature microstructure of a steel sample, and then use a '2.5D' prior austenite grain (PAG) reconstruction code to explore the relationship between the austenite phase and the room temperature microstructure. A significant result for the present work is the collection, and analysis, of data from a large volume (150 x 150 x 100 μm3, with a (200 nm)3 voxel size) which enables analysis of a complete prior austenite grain. Analysis of variants within this grain demonstrates that high-temperature twin boundaries likely govern variant selection and grain growth in the child microstructure. This suggests opportunities to engineer novel microstructures by controlling the high-temperature grain boundary character.
format Preprint
id arxiv_https___arxiv_org_abs_2603_07378
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The role of austenite twins on variant selection during decomposition in low carbon steels
Birch, Ruth M.
Britton, Ben
Poole, Warren J
Materials Science
Thermomechanical Controlled Processing (TMCP) is widely used to control the microstructure and properties of linepipe or high strength low alloy steels (HSLA). These steels are often joined by welding and used in demanding environments such as the Arctic. In these materials, the thermal path the steel experiences is critical for understanding microstructural evolution during processing. A key step is the solid-state phase transformation during cooling from the high-temperature austenite to the room-temperature microstructure which significantly influences the final mechanical properties. Specifically, the population of different variants and grain shapes that form affect the types and morphology of the grains, and grain boundary network which influence strength and toughness of the final component. In this paper, we apply 3D microscopy using a Xe-plasma focussed ion beam scanning electron microscope (pFIB-SEM) which is equipped with electron backscatter diffraction (EBSD) in a static configuration to characterize the room temperature microstructure of a steel sample, and then use a '2.5D' prior austenite grain (PAG) reconstruction code to explore the relationship between the austenite phase and the room temperature microstructure. A significant result for the present work is the collection, and analysis, of data from a large volume (150 x 150 x 100 μm3, with a (200 nm)3 voxel size) which enables analysis of a complete prior austenite grain. Analysis of variants within this grain demonstrates that high-temperature twin boundaries likely govern variant selection and grain growth in the child microstructure. This suggests opportunities to engineer novel microstructures by controlling the high-temperature grain boundary character.
title The role of austenite twins on variant selection during decomposition in low carbon steels
topic Materials Science
url https://arxiv.org/abs/2603.07378