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Analysis of variant selection in friction‐stir‐processed high‐strength low‐alloy steels
Author(s) -
Abbasi Majid,
Nelson Tracy W.,
Sorensen Carl D.
Publication year - 2013
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889813008522
Subject(s) - misorientation , electron backscatter diffraction , nucleation , austenite , materials science , grain boundary , alloy , ferrite (magnet) , selection (genetic algorithm) , metallurgy , high strength low alloy steel , friction stir welding , crystallography , composite material , microstructure , thermodynamics , chemistry , physics , artificial intelligence , computer science
Variant selection in friction‐stir‐welded high‐strength low‐alloy steels has been studied using the electron backscatter diffraction and prior austenite (PA) reconstruction techniques described in previous papers. A hypothesis for variant selection has been proposed based on grain‐boundary interfacial energy and misorientation. This study focuses on austenite 〈111〉 boundaries with a two‐dimensional approach. Results indicate that variant selection is strongly dependent on misorientation. Certain PA misorientations produce combinations of variants that minimize the interfacial energies between a ferrite nucleus and a neighboring austenite grain, and between adjoining ferrite nuclei along the boundary between two PA grains. PA grains that exhibit a 60°〈111〉 misorientation between them satisfy both these conditions for a combination of variants. These PA boundaries exhibit strong variant selection. As a result, the density of these boundary types influences the overall variant selection. Additionally, variant selection is more prevalent in small PA grains (<150 µm), which is probably a result of limited intragranular nucleation. Nearly all variants are present in larger PA grains.