Void formation by cementite and local misorientation evaluation during tensile deformation in high strength steel sheets

Mari Maeda*, Junji Shimamura, Shinsuke Suzuki

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Voids formation by cementite was investigated quantitatively in high strength steel sheets consisting of bainitic ferrite and cementite. Tensile tests were performed with rectangular specimen in longitudinal direction to rolling direction. After the tensile tests, the fractured specimens were cut along the width center. The cross sections near the fractured surface were observed by SEM. Voids and microstructure were observed in five thickness reduction areas with different strain level. As a result, number density of voids increased as strain increased. Not only the number of short voids observed in low strain but also the number of long voids increased as strain increased. Mainly, two types of voids were seen here. One was decohesion of interface between bainitic ferrite and cementite, and the other was cracking of cementite itself. Misorientation in the crystal grains was determined by KAM (Kernel Average Misorientation) using EBSD analysis. The obtained KAM values increased as strain increased, especially in the boundaries between bainitic ferrite and cementite. Therefore, it was revealed quantitatively that voids formed mainly through local strain increase.

Original languageEnglish
Pages (from-to)483-490
Number of pages8
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume103
Issue number8
DOIs
Publication statusPublished - 2017

Keywords

  • Cementite
  • Ductile fracture
  • EBSD
  • High strength steel sheet
  • KAM
  • Void

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

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