Effects of solute segregation on tensile properties and serration behavior in ultra-high-strength high-Mn TRIP steels

Min Chul Jo; Jin Hyeok Choi; Hyungsoo Lee; A. Zargaran; Joo Hyun Ryu; Seok Su Sohn; Nack J. Kim; Sunghak Lee

doi:10.1016/j.msea.2018.10.065

Effects of solute segregation on tensile properties and serration behavior in ultra-high-strength high-Mn TRIP steels

Min Chul Jo, Jin Hyeok Choi, Hyungsoo Lee, A. Zargaran, Joo Hyun Ryu, Seok Su Sohn, Nack J. Kim, Sunghak Lee

Research output: Contribution to journal › Article › peer-review

38 Citations (Scopus)

Abstract

Austenitic high-Mn TWinning- and Transformation-Induced Plasticity (TWIP and TRIP) steels are strong candidates for GPa-grade cold-rolled steel sheets. The reduction in C or Mn content from high-Mn TWIP steels help generate a TRIP mechanism and prevent serration. However, these high-Mn TRIP steels show low yield strength because of the inherent characteristics of austenite, and often contain a band-shaped segregation of solutes, making the steels acts as hetero-structural materials. Therefore, in this study, we investigate the effects of compositionally-segregated microstructures on tensile properties and serration behavior in precipitation-hardened high-Mn TRIP steels. The present TRIP steels showed high yield strength (778–824 MPa) and an excellent strength-ductility balance, along with serration in their stress-strain curves which could not be explained by existing theories of dynamic strain aging. A considerable amount of martensite was formed step by step as localized deformation bands passed through the specimen gage section, which implied that the serration occurred only when the transformation rate increased substantially. In microstructural aspects, the martensitic transformation occurred sequentially along Mn-segregated bands due to differences in austenite stability and Mn content between high- and low-Mn bands, thereby leading to discontinuous transformation and consequently the serrated flow.

Original language	English
Pages (from-to)	16-27
Number of pages	12
Journal	Materials Science and Engineering A
Volume	740-741
DOIs	https://doi.org/10.1016/j.msea.2018.10.065
Publication status	Published - 2019 Jan 7
Externally published	Yes

Bibliographical note

Funding Information:
This work was supported by POSCO under a contract No. 2016Y029 and by Brain Korea 21 PLUS Project for Center for Creative Industrial Materials. S.S. Sohn is grateful to the kind support of the Alexander von Humboldt Stiftung (AvH, Alexander von Humboldt Foundation, https://www.humboldt –foundation.de).

Publisher Copyright:
© 2018 Elsevier B.V.

Keywords

Austenitic high-Mn steel
Segregation
Serration
Transformation-Induced Plasticity (TRIP)
Twinning-Induced Plasticity (TWIP)

ASJC Scopus subject areas

General Materials Science
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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10.1016/j.msea.2018.10.065

Cite this

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title = "Effects of solute segregation on tensile properties and serration behavior in ultra-high-strength high-Mn TRIP steels",

abstract = "Austenitic high-Mn TWinning- and Transformation-Induced Plasticity (TWIP and TRIP) steels are strong candidates for GPa-grade cold-rolled steel sheets. The reduction in C or Mn content from high-Mn TWIP steels help generate a TRIP mechanism and prevent serration. However, these high-Mn TRIP steels show low yield strength because of the inherent characteristics of austenite, and often contain a band-shaped segregation of solutes, making the steels acts as hetero-structural materials. Therefore, in this study, we investigate the effects of compositionally-segregated microstructures on tensile properties and serration behavior in precipitation-hardened high-Mn TRIP steels. The present TRIP steels showed high yield strength (778–824 MPa) and an excellent strength-ductility balance, along with serration in their stress-strain curves which could not be explained by existing theories of dynamic strain aging. A considerable amount of martensite was formed step by step as localized deformation bands passed through the specimen gage section, which implied that the serration occurred only when the transformation rate increased substantially. In microstructural aspects, the martensitic transformation occurred sequentially along Mn-segregated bands due to differences in austenite stability and Mn content between high- and low-Mn bands, thereby leading to discontinuous transformation and consequently the serrated flow.",

keywords = "Austenitic high-Mn steel, Segregation, Serration, Transformation-Induced Plasticity (TRIP), Twinning-Induced Plasticity (TWIP)",

author = "Jo, {Min Chul} and Choi, {Jin Hyeok} and Hyungsoo Lee and A. Zargaran and Ryu, {Joo Hyun} and Sohn, {Seok Su} and Kim, {Nack J.} and Sunghak Lee",

note = "Funding Information: This work was supported by POSCO under a contract No. 2016Y029 and by Brain Korea 21 PLUS Project for Center for Creative Industrial Materials. S.S. Sohn is grateful to the kind support of the Alexander von Humboldt Stiftung (AvH, Alexander von Humboldt Foundation, https://www.humboldt –foundation.de). Publisher Copyright: {\textcopyright} 2018 Elsevier B.V.",

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AU - Jo, Min Chul

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AU - Zargaran, A.

AU - Ryu, Joo Hyun

AU - Sohn, Seok Su

AU - Kim, Nack J.

AU - Lee, Sunghak

N1 - Funding Information: This work was supported by POSCO under a contract No. 2016Y029 and by Brain Korea 21 PLUS Project for Center for Creative Industrial Materials. S.S. Sohn is grateful to the kind support of the Alexander von Humboldt Stiftung (AvH, Alexander von Humboldt Foundation, https://www.humboldt –foundation.de). Publisher Copyright: © 2018 Elsevier B.V.

PY - 2019/1/7

Y1 - 2019/1/7

N2 - Austenitic high-Mn TWinning- and Transformation-Induced Plasticity (TWIP and TRIP) steels are strong candidates for GPa-grade cold-rolled steel sheets. The reduction in C or Mn content from high-Mn TWIP steels help generate a TRIP mechanism and prevent serration. However, these high-Mn TRIP steels show low yield strength because of the inherent characteristics of austenite, and often contain a band-shaped segregation of solutes, making the steels acts as hetero-structural materials. Therefore, in this study, we investigate the effects of compositionally-segregated microstructures on tensile properties and serration behavior in precipitation-hardened high-Mn TRIP steels. The present TRIP steels showed high yield strength (778–824 MPa) and an excellent strength-ductility balance, along with serration in their stress-strain curves which could not be explained by existing theories of dynamic strain aging. A considerable amount of martensite was formed step by step as localized deformation bands passed through the specimen gage section, which implied that the serration occurred only when the transformation rate increased substantially. In microstructural aspects, the martensitic transformation occurred sequentially along Mn-segregated bands due to differences in austenite stability and Mn content between high- and low-Mn bands, thereby leading to discontinuous transformation and consequently the serrated flow.

AB - Austenitic high-Mn TWinning- and Transformation-Induced Plasticity (TWIP and TRIP) steels are strong candidates for GPa-grade cold-rolled steel sheets. The reduction in C or Mn content from high-Mn TWIP steels help generate a TRIP mechanism and prevent serration. However, these high-Mn TRIP steels show low yield strength because of the inherent characteristics of austenite, and often contain a band-shaped segregation of solutes, making the steels acts as hetero-structural materials. Therefore, in this study, we investigate the effects of compositionally-segregated microstructures on tensile properties and serration behavior in precipitation-hardened high-Mn TRIP steels. The present TRIP steels showed high yield strength (778–824 MPa) and an excellent strength-ductility balance, along with serration in their stress-strain curves which could not be explained by existing theories of dynamic strain aging. A considerable amount of martensite was formed step by step as localized deformation bands passed through the specimen gage section, which implied that the serration occurred only when the transformation rate increased substantially. In microstructural aspects, the martensitic transformation occurred sequentially along Mn-segregated bands due to differences in austenite stability and Mn content between high- and low-Mn bands, thereby leading to discontinuous transformation and consequently the serrated flow.

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KW - Serration

KW - Transformation-Induced Plasticity (TRIP)

KW - Twinning-Induced Plasticity (TWIP)

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M3 - Article

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SN - 0921-5093

VL - 740-741

SP - 16

EP - 27

JO - Materials Science and Engineering A

JF - Materials Science and Engineering A

ER -

Effects of solute segregation on tensile properties and serration behavior in ultra-high-strength high-Mn TRIP steels

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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