Correlation between fracture toughness and stretch-flangeability of advanced high strength steels

Jae Ik Yoon, Jaimyun Jung, Soo Hyun Joo, Tae Jin Song, Kwang Geun Chin, Min Hong Seo, Sung Joon Kim, Sunghak Lee, Hyoung Seop Kim

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


Stretch-flangeability representing the capability of a sheet material to form into a complex shaped part is not a well-known sheet metal forming property. We correlate mechanical properties with stretch-flangeability of various advanced high strength steels (AHSSs) to capture the stretch-flanging phenomenon and improve the stretch-flangeability of steel sheet materials. The stretch-flangeability of materials is usually evaluated using a hole expansion test. During the hole expansion test, the stress state in the hole edge part of the specimen is almost the same as that of the uniaxial tensile test. However, a single parameter in tensile properties of the AHSSs exhibits no clear correlation with flangeability estimated as the hole expansion ratio (HER). Because micro-cracks in the hole edge region of the hole expansion testing samples play a significant role in HER values, we propose and demonstrate that fracture toughness is the key factor governing the HER of AHSSs.

Original languageEnglish
Pages (from-to)322-326
Number of pages5
JournalMaterials Letters
Publication statusPublished - 2016 Oct 1


  • Advanced high strength steels
  • Deformation and fracture
  • Hole expansion ratio
  • Metal forming and shaping
  • Metals and alloys
  • Tensile properties

ASJC Scopus subject areas

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


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