Comparative Investigation of Edge Cracking Behavior in 600 MPa Dual Phase (DU) Steel Sheets from Different Manufacturers

Recent advancements in the automotive industry have emphasized the importance of fuel efficiency, weight reduction, and durability. In response, AHSS materials have become widely used, particularly in cold forming. However, their high strength reduces formability, leading to challenges such as edge cracking. In this study, 600DU steel from two different mills was tested. Tensile tests were conducted on EU1 and EU2 at 0°, 45°, and 90° to the rolling direction per JIS Z 2241 No. 5. The tensile strength values were similar, but EU2 showed higher elongation. A hole expansion test revealed an average expansion of ~27% for EU1 and ~60% for EU2. Vickers hardness was measured under an HV 10 load. Metallographic preparation was followed by microstructural analysis using optical and SEM microscopy. In the AutoForm simulation analysis, the average thickness reduction of the EU1 steel was determined to be 19%, while that of the EU2 steel was measured at 11%. These results indicate that the EU1 steel exhibits 8% greater thinning compared to the EU2 steel. This study examines the formability of 600DU (dual-phase) AHSS steel from different manufacturers using numerical and experimental methods. The findings provide key insights into AHSS forming performance and help address potential issues. Numerical and experimental data modeling will contribute to optimizing manufacturing processes.