Post-uniform elongation and tensile fracture mechanisms of Fe-18Mn-0.6C-xAl twinning-induced plasticity steels

Ha Young Yu, Sang Min Lee, Jae Hoon Nam, Seung Joon Lee, Damien Fabrègue, Myeong heom Park, Nobuhiro Tsuji, Young Kook Lee

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

The objective of the present study was to elucidate the complicated interrelationship between necking, post-uniform elongation (epu), strain rate sensitivity (SRS), fracture mechanism and Al concentration in Fe-18Mn-0.6C-xAl twinning-induced plasticity steels. Many tensile tests were conducted for in- and ex-situ observations of necking, fracture surfaces, crack propagation and the density and size of micro-voids with the assistance of a high-speed camera and X-ray tomographic equipment. The addition of Al increased epu, SRS and reduction ratios in dimension of the neck part of tensile specimens, and also changed fracture mode from quasi-cleavage to ductile fracture at the edge part. The quasi-cleavage surface of Al-free specimen was induced by edge and side cracks occurring along grain boundary junctions and twin boundaries within the edges and side surfaces where local deformation bands meet. The ductile-fracture surface of 1.5 %Al-added specimen was formed by the coalescence of micro-voids. While the side-to-middle crack propagation occurred in Al-free and 1 %Al-added specimens due to side cracks, the middle-to-side crack propagation was observed in 1.5 %Al-added specimen. The Al-free specimen had the larger size of the 20 largest voids compared to the 1.5 %Al-added specimen despite its lower void density and local strain due to the accelerated growth of voids near the tips of side cracks. Evaluating the negligible epu of Al-free specimen by SRS is not deemed to be reasonable due to its inappreciable necking and side cracks. The improvement of epu in 1.5 %Al-added specimen is primarily due to disappearance of edge and side cracks.

Original languageEnglish
Pages (from-to)435-444
Number of pages10
JournalActa Materialia
Volume131
DOIs
Publication statusPublished - 2017 Jun 1

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Steel
Twinning
Plasticity
Elongation
Cracks
Strain rate
Crack propagation
Ductile fracture
High speed cameras
Coalescence
Grain boundaries
X rays

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

Cite this

Yu, Ha Young ; Lee, Sang Min ; Nam, Jae Hoon ; Lee, Seung Joon ; Fabrègue, Damien ; Park, Myeong heom ; Tsuji, Nobuhiro ; Lee, Young Kook. / Post-uniform elongation and tensile fracture mechanisms of Fe-18Mn-0.6C-xAl twinning-induced plasticity steels. In: Acta Materialia. 2017 ; Vol. 131. pp. 435-444.
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abstract = "The objective of the present study was to elucidate the complicated interrelationship between necking, post-uniform elongation (epu), strain rate sensitivity (SRS), fracture mechanism and Al concentration in Fe-18Mn-0.6C-xAl twinning-induced plasticity steels. Many tensile tests were conducted for in- and ex-situ observations of necking, fracture surfaces, crack propagation and the density and size of micro-voids with the assistance of a high-speed camera and X-ray tomographic equipment. The addition of Al increased epu, SRS and reduction ratios in dimension of the neck part of tensile specimens, and also changed fracture mode from quasi-cleavage to ductile fracture at the edge part. The quasi-cleavage surface of Al-free specimen was induced by edge and side cracks occurring along grain boundary junctions and twin boundaries within the edges and side surfaces where local deformation bands meet. The ductile-fracture surface of 1.5 {\%}Al-added specimen was formed by the coalescence of micro-voids. While the side-to-middle crack propagation occurred in Al-free and 1 {\%}Al-added specimens due to side cracks, the middle-to-side crack propagation was observed in 1.5 {\%}Al-added specimen. The Al-free specimen had the larger size of the 20 largest voids compared to the 1.5 {\%}Al-added specimen despite its lower void density and local strain due to the accelerated growth of voids near the tips of side cracks. Evaluating the negligible epu of Al-free specimen by SRS is not deemed to be reasonable due to its inappreciable necking and side cracks. The improvement of epu in 1.5 {\%}Al-added specimen is primarily due to disappearance of edge and side cracks.",
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Post-uniform elongation and tensile fracture mechanisms of Fe-18Mn-0.6C-xAl twinning-induced plasticity steels. / Yu, Ha Young; Lee, Sang Min; Nam, Jae Hoon; Lee, Seung Joon; Fabrègue, Damien; Park, Myeong heom; Tsuji, Nobuhiro; Lee, Young Kook.

In: Acta Materialia, Vol. 131, 01.06.2017, p. 435-444.

Research output: Contribution to journalArticle

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AB - The objective of the present study was to elucidate the complicated interrelationship between necking, post-uniform elongation (epu), strain rate sensitivity (SRS), fracture mechanism and Al concentration in Fe-18Mn-0.6C-xAl twinning-induced plasticity steels. Many tensile tests were conducted for in- and ex-situ observations of necking, fracture surfaces, crack propagation and the density and size of micro-voids with the assistance of a high-speed camera and X-ray tomographic equipment. The addition of Al increased epu, SRS and reduction ratios in dimension of the neck part of tensile specimens, and also changed fracture mode from quasi-cleavage to ductile fracture at the edge part. The quasi-cleavage surface of Al-free specimen was induced by edge and side cracks occurring along grain boundary junctions and twin boundaries within the edges and side surfaces where local deformation bands meet. The ductile-fracture surface of 1.5 %Al-added specimen was formed by the coalescence of micro-voids. While the side-to-middle crack propagation occurred in Al-free and 1 %Al-added specimens due to side cracks, the middle-to-side crack propagation was observed in 1.5 %Al-added specimen. The Al-free specimen had the larger size of the 20 largest voids compared to the 1.5 %Al-added specimen despite its lower void density and local strain due to the accelerated growth of voids near the tips of side cracks. Evaluating the negligible epu of Al-free specimen by SRS is not deemed to be reasonable due to its inappreciable necking and side cracks. The improvement of epu in 1.5 %Al-added specimen is primarily due to disappearance of edge and side cracks.

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