Application of Digital Image Processing Techniques to Detect Through-Thickness Crack in Hole Expansion Test

Advanced high-strength steels (AHSS) have become increasingly popular in the automotive industry due to their high yield and ultimate tensile strengths, enabling production of lighter car body structures while meeting safety standards. However, they some setbacks compared conventional steels, such as edge cracking through sheet thickness caused by forming components with shear-cut edges. When characterizing formability metal materials, hole expansion test is an industry-standard method used evaluate stretch-flangeability accurately visualizing first usually tricky may be subjective, often leading inconsistent results low reproducibility impact operator on both direct post-processing measurements. To address these issues, a novel digital image processing presented reduce reliance enhance accuracy efficiency results. By leveraging advanced algorithms, proposed approach detects appearance cracks, more precise determination ratio (HER). Furthermore, it provides valuable insights into evolution diameter, allowing for comprehensive understanding material behavior during test. The was evaluated different corresponding HER values were traditional method.