Key factors of stretch-flangeability of sheet materials

Jae Ik Yoon, Jaimyun Jung, Jung Gi Kim, Seok Su Sohn, Sunghak Lee, Hyoung Seop Kim

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


Stretch-flangeability evaluated using hole-expansion testing represents the ability of sheet materials to resist edge fracture during complex shape forming. Despite a property imperative for automotive part applications of advanced high-strength steels, factors governing stretch-flangeability are not yet well understood. In this study, the mechanical properties of a selected group of materials with different microstructures were investigated using tensile, fracture toughness, and hole-expansion tests to find the factor governing the stretch-flangeability that is universally applicable to a variety of metallic materials. It was found that the fracture toughness of materials, measured using the fracture initiation energy, is a universal factor governing stretch-flangeability. We verified that fracture toughness is the key factor governing stretch-flangeability, showing that the hole-expansion ratio could be well predicted using finite element analysis associated with a simple ductile damage model, without explicitly taking into account the microstructural complexity of each specimen. This validates the use of the fracture toughness as a key factor of stretch-flangeability.

Original languageEnglish
Pages (from-to)7808-7823
Number of pages16
JournalJournal of Materials Science
Issue number13
Publication statusPublished - 2017 Jul 1
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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