Key factors of stretch-flangeability of sheet materials

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 no...

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Bibliographic Details
Published inJournal of materials science Vol. 52; no. 13; pp. 7808 - 7823
Main Authors Yoon, Jae Ik, Jung, Jaimyun, Kim, Jung Gi, Sohn, Seok Su, Lee, Sunghak, Kim, Hyoung Seop
Format Journal Article
LanguageEnglish
Published New York Springer US 01.07.2017
Springer
Springer Nature B.V
Subjects
Automotive parts
Characterization and Evaluation of Materials
Chemistry and Materials Science
Classical Mechanics
Complexity
Crack initiation
Crystallography and Scattering Methods
Damage assessment
Ductile fracture
Finite element method
Fracture mechanics
Fracture toughness
Heat treating
High strength steels
Materials Science
Materials selection
Mechanical properties
Metals
Microstructure
Polymer Sciences
Solid Mechanics
Structural steels
Fracture Toughness
Digital Image Correlation
Fracture Toughness Test
Fracture Energy
Sheet Material
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Summary: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.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-017-1012-y