Prediction of hole expansion ratio for various steel sheets based on uniaxial tensile properties

• Published in: Metals and materials international Vol. 24; no. 1; pp. 187 - 194
• Main Authors: Kim, Jae Hyung, Kwon, Young Jin, Lee, Taekyung, Lee, Kee-Ahn, Kim, Hyoung Seop, Lee, Chong Soo
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 2018; Springer Nature B.V; 대한금속·재료학회
• Subjects: Austenitic stainless steels; Automobile industry; Automobiles; Automotive engineering; Characterization and Evaluation of Materials; Chemistry and Materials Science; Deformation; Elongation; Engineering Thermodynamics; Heat and Mass Transfer; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Metal sheets; Metallic Materials; Predictions; Processes; Solid Mechanics; Steel; Structural steels; Tensile properties; 재료공학; metals; plasticity; tensile test; mechanical properties; fracture
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-017-7288-2

Stretch-flangeability is one of important formability parameters of thin steel sheets used in the automotive industry. There have been many attempts to predict hole expansion ratio (HER), a typical term to evaluate stretch-flangeability, using uniaxial tensile properties for convenience. This paper suggests a new approach that uses total elongation and average normal anisotropy to predict HER of thin steel sheets. The method provides a good linear relationship between HER of the machined hole and the predictive variables in a variety of materials with different microstructures obtained using different processing methods. The HER of the punched hole was also well predicted using the similar approach, which reflected only the portion of post uniform elongation. The physical meaning drawn by our approach successfully explained the poor HER of austenitic steels despite their considerable elongation. The proposed method to predict HER is simple and cost-effective, so it will be useful in industry. In addition, the model provides a physical explanation of HER, so it will be useful in academia.