Relationship between grain size and ductile-to-brittle transition at room temperature in Fe-18Mn-0.6C-1.5Si twinning-induced plasticity steel

Seo Yeon Jo, Jeongho Han, Joo Hee Kang, Singon Kang, Sukjin Lee, Young-Kook Lee

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The effect of grain size on tensile properties, particularly elongation (El), was systematically investigated using cold-rolled and annealed Fe-18Mn-0.6C-1.5Si (wt.%) twinning-induced plasticity (TWIP) steels. Whereas both the yield (YS) and ultimate tensile strengths (UTS) decreased with grain coarsening, the El increased up to a grain size of approximately 18 μm, and then sharply decreased beyond the critical grain size. This unusual reduction in El in coarse-grained specimens was caused by the transition of the fracture mode from ductile to brittle. The transition in fracture stemmed from a change in the deformation mechanism from mechanical twinning to strain-induced ε-martensitic transformation. The ε plates provided nucleation sites and propagation paths for cracks, causing quasi-cleavage brittle fracture in coarse-grained specimens. The cracks growing along the {101¯0} or (0 0 0 1) plane were bent by ε plates with different plane orientations and were blocked by γ-austenite plates. When the local stress in the γ plate near the crack tip was high, new ε-martensitic plates formed within the γ plate, enabling the crack to pass through the γ plate, and changed the crack path. The quasi-cleavage fractured surface consisted of (101¯1), (101¯2), and (21¯1¯1) planes. Ridges of bamboo-like structures observed on the fractured surface formed by the variation in crack path occurring at the ε plates with different orientations. The Si-added TWIP steel exhibited a superior combination of UTS and El of more than 70,000 MPa %.

Original languageEnglish
Pages (from-to)374-382
Number of pages9
JournalJournal of Alloys and Compounds
Volume627
DOIs
Publication statusPublished - 2015 Apr 5

Fingerprint

Steel
Twinning
Plasticity
Elongation
Cracks
Tensile strength
Temperature
Bamboo
Martensitic transformations
Brittle fracture
Coarsening
Tensile properties
Crack tips
Crystal orientation
Austenite
Crack propagation
Nucleation

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

Cite this

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title = "Relationship between grain size and ductile-to-brittle transition at room temperature in Fe-18Mn-0.6C-1.5Si twinning-induced plasticity steel",
abstract = "The effect of grain size on tensile properties, particularly elongation (El), was systematically investigated using cold-rolled and annealed Fe-18Mn-0.6C-1.5Si (wt.{\%}) twinning-induced plasticity (TWIP) steels. Whereas both the yield (YS) and ultimate tensile strengths (UTS) decreased with grain coarsening, the El increased up to a grain size of approximately 18 μm, and then sharply decreased beyond the critical grain size. This unusual reduction in El in coarse-grained specimens was caused by the transition of the fracture mode from ductile to brittle. The transition in fracture stemmed from a change in the deformation mechanism from mechanical twinning to strain-induced ε-martensitic transformation. The ε plates provided nucleation sites and propagation paths for cracks, causing quasi-cleavage brittle fracture in coarse-grained specimens. The cracks growing along the {101¯0} or (0 0 0 1) plane were bent by ε plates with different plane orientations and were blocked by γ-austenite plates. When the local stress in the γ plate near the crack tip was high, new ε-martensitic plates formed within the γ plate, enabling the crack to pass through the γ plate, and changed the crack path. The quasi-cleavage fractured surface consisted of (101¯1), (101¯2), and (21¯1¯1) planes. Ridges of bamboo-like structures observed on the fractured surface formed by the variation in crack path occurring at the ε plates with different orientations. The Si-added TWIP steel exhibited a superior combination of UTS and El of more than 70,000 MPa {\%}.",
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Relationship between grain size and ductile-to-brittle transition at room temperature in Fe-18Mn-0.6C-1.5Si twinning-induced plasticity steel. / Jo, Seo Yeon; Han, Jeongho; Kang, Joo Hee; Kang, Singon; Lee, Sukjin; Lee, Young-Kook.

In: Journal of Alloys and Compounds, Vol. 627, 05.04.2015, p. 374-382.

Research output: Contribution to journalArticle

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AU - Jo, Seo Yeon

AU - Han, Jeongho

AU - Kang, Joo Hee

AU - Kang, Singon

AU - Lee, Sukjin

AU - Lee, Young-Kook

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N2 - The effect of grain size on tensile properties, particularly elongation (El), was systematically investigated using cold-rolled and annealed Fe-18Mn-0.6C-1.5Si (wt.%) twinning-induced plasticity (TWIP) steels. Whereas both the yield (YS) and ultimate tensile strengths (UTS) decreased with grain coarsening, the El increased up to a grain size of approximately 18 μm, and then sharply decreased beyond the critical grain size. This unusual reduction in El in coarse-grained specimens was caused by the transition of the fracture mode from ductile to brittle. The transition in fracture stemmed from a change in the deformation mechanism from mechanical twinning to strain-induced ε-martensitic transformation. The ε plates provided nucleation sites and propagation paths for cracks, causing quasi-cleavage brittle fracture in coarse-grained specimens. The cracks growing along the {101¯0} or (0 0 0 1) plane were bent by ε plates with different plane orientations and were blocked by γ-austenite plates. When the local stress in the γ plate near the crack tip was high, new ε-martensitic plates formed within the γ plate, enabling the crack to pass through the γ plate, and changed the crack path. The quasi-cleavage fractured surface consisted of (101¯1), (101¯2), and (21¯1¯1) planes. Ridges of bamboo-like structures observed on the fractured surface formed by the variation in crack path occurring at the ε plates with different orientations. The Si-added TWIP steel exhibited a superior combination of UTS and El of more than 70,000 MPa %.

AB - The effect of grain size on tensile properties, particularly elongation (El), was systematically investigated using cold-rolled and annealed Fe-18Mn-0.6C-1.5Si (wt.%) twinning-induced plasticity (TWIP) steels. Whereas both the yield (YS) and ultimate tensile strengths (UTS) decreased with grain coarsening, the El increased up to a grain size of approximately 18 μm, and then sharply decreased beyond the critical grain size. This unusual reduction in El in coarse-grained specimens was caused by the transition of the fracture mode from ductile to brittle. The transition in fracture stemmed from a change in the deformation mechanism from mechanical twinning to strain-induced ε-martensitic transformation. The ε plates provided nucleation sites and propagation paths for cracks, causing quasi-cleavage brittle fracture in coarse-grained specimens. The cracks growing along the {101¯0} or (0 0 0 1) plane were bent by ε plates with different plane orientations and were blocked by γ-austenite plates. When the local stress in the γ plate near the crack tip was high, new ε-martensitic plates formed within the γ plate, enabling the crack to pass through the γ plate, and changed the crack path. The quasi-cleavage fractured surface consisted of (101¯1), (101¯2), and (21¯1¯1) planes. Ridges of bamboo-like structures observed on the fractured surface formed by the variation in crack path occurring at the ε plates with different orientations. The Si-added TWIP steel exhibited a superior combination of UTS and El of more than 70,000 MPa %.

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SN - 0925-8388

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