Revealing the mechanical and microstructural performance of multiphase steels during tensile, forming and flanging operations

P. Efthymiadis, S. Hazra, A. Clough, R. Lakshmi, A. Alamoudi, R. Dashwood, B. Shollock

Research output: Contribution to journalArticle

9 Citations (Scopus)
15 Downloads (Pure)

Abstract

The mechanical performance of Dual Phase (DP) and Complex Phase (CP) steels was investigated by SEM analysis, tensile testing, Forming Limit Curve investigation and flange formability testing. The alloys of interest were Dual Phase (DP) untempered, Dual Phase (DP) tempered and Complex Phase (CP) steels. Phase content analysis showed that the distribution of the ferrite and martensite phases was the same for the two DP alloys, but the grain size and condition (tempered/untempered) for the martensite islands was much different in the two alloys. In the tempered DP steel, the smaller grain size for the martensite and the tempering process resulted in increased elongation, more formability and ability to form a flange (flangeability). In CP steels the soft ferrite phase is replaced by harder bainite, yielding a bainitic-martensitic microstructure. Bainite reduced the total elongation of the alloy during tensile testing, reduced the formability (especially under plane strain conditions) of the alloy but improved the flangeability of the alloy. Under flanging conditions, CP steels deformed to higher strains, at tighter radii with minimum springback. Microstructural inspections at the outer radius of the flanged specimens revealed that in CP steels bainite deforms similarly to martensite, therefore the strain partitioning is smaller in CP steels in comparison to DP steels. Plastic deformation in CP steels upon flanging occurs with the formation of strong slip bands in both martensite and bainite. In contrast, the martensite and ferrite grains in DP steels deform quite differently leading to strong strain localisations. Void nucleation and cracking occurred at the martensite islands or within the soft ferrite phase next to the martensite islands. In CP steels no voids or damage was observed within the matrix. A special case study was done with a thicker and stronger alloy, a Martensitic 1400 steel to reveal the flangeability limits for advanced high strength steels. Neither cracks nor damage were observed visually on the flanged specimens. However SEM observations at the outer radius of the flanged samples revealed significant void growth at inclusion sites and cracks nucleating within the matrix adjacent to the inclusions.


Publisher Statement: This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/)

Original languageEnglish
Pages (from-to)174-186
Number of pages13
JournalMaterials Science and Engineering A
Volume701
Early online date22 Jun 2017
DOIs
Publication statusPublished - 31 Jul 2017

Fingerprint

Steel
steels
Martensite
martensite
Bainite
bainite
Ferrite
ferrites
Formability
voids
flanges
Tensile testing
Flanges
Elongation
elongation
radii
cracks
grain size
Cracks
inclusions

Keywords

  • Flanging
  • Formability
  • Microstructure properties-mechanical performance correlation
  • Springback
  • Ultra high strength steels

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Revealing the mechanical and microstructural performance of multiphase steels during tensile, forming and flanging operations. / Efthymiadis, P.; Hazra, S.; Clough, A.; Lakshmi, R.; Alamoudi, A.; Dashwood, R.; Shollock, B.

In: Materials Science and Engineering A, Vol. 701, 31.07.2017, p. 174-186.

Research output: Contribution to journalArticle

Efthymiadis, P. ; Hazra, S. ; Clough, A. ; Lakshmi, R. ; Alamoudi, A. ; Dashwood, R. ; Shollock, B. / Revealing the mechanical and microstructural performance of multiphase steels during tensile, forming and flanging operations. In: Materials Science and Engineering A. 2017 ; Vol. 701. pp. 174-186.
@article{b71bb9eda9f444429942c44cd4fccb3e,
title = "Revealing the mechanical and microstructural performance of multiphase steels during tensile, forming and flanging operations",
abstract = "The mechanical performance of Dual Phase (DP) and Complex Phase (CP) steels was investigated by SEM analysis, tensile testing, Forming Limit Curve investigation and flange formability testing. The alloys of interest were Dual Phase (DP) untempered, Dual Phase (DP) tempered and Complex Phase (CP) steels. Phase content analysis showed that the distribution of the ferrite and martensite phases was the same for the two DP alloys, but the grain size and condition (tempered/untempered) for the martensite islands was much different in the two alloys. In the tempered DP steel, the smaller grain size for the martensite and the tempering process resulted in increased elongation, more formability and ability to form a flange (flangeability). In CP steels the soft ferrite phase is replaced by harder bainite, yielding a bainitic-martensitic microstructure. Bainite reduced the total elongation of the alloy during tensile testing, reduced the formability (especially under plane strain conditions) of the alloy but improved the flangeability of the alloy. Under flanging conditions, CP steels deformed to higher strains, at tighter radii with minimum springback. Microstructural inspections at the outer radius of the flanged specimens revealed that in CP steels bainite deforms similarly to martensite, therefore the strain partitioning is smaller in CP steels in comparison to DP steels. Plastic deformation in CP steels upon flanging occurs with the formation of strong slip bands in both martensite and bainite. In contrast, the martensite and ferrite grains in DP steels deform quite differently leading to strong strain localisations. Void nucleation and cracking occurred at the martensite islands or within the soft ferrite phase next to the martensite islands. In CP steels no voids or damage was observed within the matrix. A special case study was done with a thicker and stronger alloy, a Martensitic 1400 steel to reveal the flangeability limits for advanced high strength steels. Neither cracks nor damage were observed visually on the flanged specimens. However SEM observations at the outer radius of the flanged samples revealed significant void growth at inclusion sites and cracks nucleating within the matrix adjacent to the inclusions.Publisher Statement: This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/)",
keywords = "Flanging, Formability, Microstructure properties-mechanical performance correlation, Springback, Ultra high strength steels",
author = "P. Efthymiadis and S. Hazra and A. Clough and R. Lakshmi and A. Alamoudi and R. Dashwood and B. Shollock",
year = "2017",
month = "7",
day = "31",
doi = "10.1016/j.msea.2017.06.056",
language = "English",
volume = "701",
pages = "174--186",
journal = "Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing",
issn = "0921-5093",
publisher = "Elsevier",

}

TY - JOUR

T1 - Revealing the mechanical and microstructural performance of multiphase steels during tensile, forming and flanging operations

AU - Efthymiadis, P.

AU - Hazra, S.

AU - Clough, A.

AU - Lakshmi, R.

AU - Alamoudi, A.

AU - Dashwood, R.

AU - Shollock, B.

PY - 2017/7/31

Y1 - 2017/7/31

N2 - The mechanical performance of Dual Phase (DP) and Complex Phase (CP) steels was investigated by SEM analysis, tensile testing, Forming Limit Curve investigation and flange formability testing. The alloys of interest were Dual Phase (DP) untempered, Dual Phase (DP) tempered and Complex Phase (CP) steels. Phase content analysis showed that the distribution of the ferrite and martensite phases was the same for the two DP alloys, but the grain size and condition (tempered/untempered) for the martensite islands was much different in the two alloys. In the tempered DP steel, the smaller grain size for the martensite and the tempering process resulted in increased elongation, more formability and ability to form a flange (flangeability). In CP steels the soft ferrite phase is replaced by harder bainite, yielding a bainitic-martensitic microstructure. Bainite reduced the total elongation of the alloy during tensile testing, reduced the formability (especially under plane strain conditions) of the alloy but improved the flangeability of the alloy. Under flanging conditions, CP steels deformed to higher strains, at tighter radii with minimum springback. Microstructural inspections at the outer radius of the flanged specimens revealed that in CP steels bainite deforms similarly to martensite, therefore the strain partitioning is smaller in CP steels in comparison to DP steels. Plastic deformation in CP steels upon flanging occurs with the formation of strong slip bands in both martensite and bainite. In contrast, the martensite and ferrite grains in DP steels deform quite differently leading to strong strain localisations. Void nucleation and cracking occurred at the martensite islands or within the soft ferrite phase next to the martensite islands. In CP steels no voids or damage was observed within the matrix. A special case study was done with a thicker and stronger alloy, a Martensitic 1400 steel to reveal the flangeability limits for advanced high strength steels. Neither cracks nor damage were observed visually on the flanged specimens. However SEM observations at the outer radius of the flanged samples revealed significant void growth at inclusion sites and cracks nucleating within the matrix adjacent to the inclusions.Publisher Statement: This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/)

AB - The mechanical performance of Dual Phase (DP) and Complex Phase (CP) steels was investigated by SEM analysis, tensile testing, Forming Limit Curve investigation and flange formability testing. The alloys of interest were Dual Phase (DP) untempered, Dual Phase (DP) tempered and Complex Phase (CP) steels. Phase content analysis showed that the distribution of the ferrite and martensite phases was the same for the two DP alloys, but the grain size and condition (tempered/untempered) for the martensite islands was much different in the two alloys. In the tempered DP steel, the smaller grain size for the martensite and the tempering process resulted in increased elongation, more formability and ability to form a flange (flangeability). In CP steels the soft ferrite phase is replaced by harder bainite, yielding a bainitic-martensitic microstructure. Bainite reduced the total elongation of the alloy during tensile testing, reduced the formability (especially under plane strain conditions) of the alloy but improved the flangeability of the alloy. Under flanging conditions, CP steels deformed to higher strains, at tighter radii with minimum springback. Microstructural inspections at the outer radius of the flanged specimens revealed that in CP steels bainite deforms similarly to martensite, therefore the strain partitioning is smaller in CP steels in comparison to DP steels. Plastic deformation in CP steels upon flanging occurs with the formation of strong slip bands in both martensite and bainite. In contrast, the martensite and ferrite grains in DP steels deform quite differently leading to strong strain localisations. Void nucleation and cracking occurred at the martensite islands or within the soft ferrite phase next to the martensite islands. In CP steels no voids or damage was observed within the matrix. A special case study was done with a thicker and stronger alloy, a Martensitic 1400 steel to reveal the flangeability limits for advanced high strength steels. Neither cracks nor damage were observed visually on the flanged specimens. However SEM observations at the outer radius of the flanged samples revealed significant void growth at inclusion sites and cracks nucleating within the matrix adjacent to the inclusions.Publisher Statement: This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/)

KW - Flanging

KW - Formability

KW - Microstructure properties-mechanical performance correlation

KW - Springback

KW - Ultra high strength steels

U2 - 10.1016/j.msea.2017.06.056

DO - 10.1016/j.msea.2017.06.056

M3 - Article

VL - 701

SP - 174

EP - 186

JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

SN - 0921-5093

ER -