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

Abstract

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.

Keywords

• Advanced High-Strength
• Steel (AHSS)
• Dual-Phase Steel
• Cold Forming
• Formability
• Numerical and Experimental Methods.

Supporting Institution

TOYOTETSU Otomotiv Parçaları San. ve Tic. A.Ş.

Ethical Statement

All methods used in this study have been carried out in accordance with relevant ethical guidelines and international standards. There are no conflicts of interest among the authors. The study has been conducted as an independent scientific research, and all findings are based on the principles of integrity and accuracy.

Thanks

TOYOTETSU Türkiye provided support for the production and analysis of the materials used in this study.

References

1. [1] Mutafi, A., Yidris, N., Koloor, S.S.R., Petrů, M. Numerical Prediction of Residual Stresses Distribution in Thin-Walled Press-Braked Stainless Steel Sections, 13(2020), 5378.
2. [2] Hu, Xiaohua., and Feng, Zhili ,2021, Advanced High-Strength Steel - Basics and Applications in the Automotive Industry, United States.
3. [3] Nanda T., Singh V., Singh V., Chakraborty A, Sharma S. Third generation of advanced high-strength steels: Processing routes and properties, 233(2019), 209-238.
4. [4] Galán, J., Samek, L., Verleysen, P., Verbeken, K., & Houbaert, Y. (2012). Advanced high strength steels for automotive industry 48(2012), 118-131.
5. [5] Cui H, Li D, Fu Q, Lu Z, Xu J, Jiang N. Research on Forming Limit Stress Diagram of Advanced High Strength Dual-Phase Steel Sheets. Materials 16(2023),4543.
6. [6] Jean-Hubert Schmitt , Thierry Iung. New developments of advanced high-strength steels for automotive applications, 19(2018), 641-656.
7. [7] Yuntian Zhu, Xiaolei Wu. Heterostructured materials, 131(2023), 101019.
8. [8] WorldAutoSteels Advanced High-Strength Steels Application Guidelines Version 6.0, https://www.worldautosteel.org/download_files/AHSS%20Guidelines%20V6/00_AHSSGuidelines_V6_20170430.pdf (Access date: April 2017)

9. [9] Saai, A., Hopperstad, O.S., Fritz, J. et al. A numerical study on the effects of DU steel microstructure on the yield locus and the stress–strain response under strain path change, 16(2023)
10. [10] Taamjeed Rahmaan, 2015. Low to High Strain Rate Characterization of DP600, TRIP780, AA5182-OM. Department of Mechanical and Mechatronics Engineering the University of Waterloo, Master of Science Thesıs, 147s. Waterloo.
11. [11] Tısza M. Development of Advanced High Strength Automotive Steels, 4(2021), 9-17.
12. [12] Merve Çobanoğlu, 2019. Damage ın Dual Phase Steels Under Industrıal Formıng Condıtıons. School of natural and applıed scıences of Middle East Technical University, Master of Science Thesıs, 140, Ankara.
13. [13] Hall, J., Coryell, J., Wendt, B., and Adamski, D. Case Studies of Edge Fracture of Dual Phase Steel Stampings, 8(2015), 783-788.
14. [14] Hulka, Klaus. Modern Multi-Phase Steels for the Automotive Industry, 414–415(2003), 101–110.
15. [15] Berkay Bayramin, 2017. Dynamıc Straın Agıng of Dual Phase Steels ın Formıng Applıcatıons Mıddle East Technıcal Unıversıty, Natural and Applıed Scıences Master of Science Thesıs, 85, Ankara.
16. [16] Habibi, N., Mathi, S., Beier, T., Könemann, M. Münstermann, S. Effects of Microstructural Properties on Damage Evolution and Edge Crack Sensitivity of DP1000 Steels,12(2022), 845.
17. [17] M, R., S.K., Schmidova, E., Konopík, P., Melzer, D., Bozkurt, F., V Londe, N. Fracture Toughness Analysis of Automotive-Grade Dual-Phase Steel Using Essential Work of Fracture (EWF) Method, 10(2020), 1019.
18. [18] Zinan Li, Yuling Chang, Wenqi Liu, Junhe Lian. Predicting edge fracture in dual-phase steels: Significance of anisotropy-induced localization, 274(2024), 109255.
19. [19] Xin Wua, Hamed Bahmanpour , Ken Schmid. Characterization of Mechanically Sheared Edges of Dual Phase Steels 212(2012), 1209-1224.
20. [20] Carlos R.M.Silva, F.J.G Silva. Investigations on the edge crack defect in Dual Phase steel stamping process, 17(2018), 737-745.
21. [21] Habibi, N., Beier, T., Richter, H., Könemann, M., & Münstermann, S2019. The effects of shear affected zone on edge crack sensitivity in dual-phase steels. In IOP Conference Series: Materials Science and Engineering (Vol. 651, November, 012073. Netherlands.
22. [22] Khalilabad, M.M., Perdahcıoğlu, S., Atzema. Initiation and growth of edge cracks after shear cutting of dual-phase steel, 127(2023), 2327–2341.
23. [23] Peter Sachnik, Sheikh Enamul Hoque, Wolfram Volk. Burr-free cutting edges by notch-shear cutting, 249 (2017), 229-245.
24. [24] Nasheralahkami, S., Zhou, W., and Golovashchenko, S. Study of sheared edge formability of ultra-high strength DP980 sheet metal blanks, 141(2019), 091009.
25. [25] Vukota Boljanovic. 2004. Sheet Metal Forming Process And Die Design, America, 230s.
26. [26] Bassini, E.; Sivo, A.; Ugues, D. Assessment of the Hardening Behavior and Tensile Properties of a Cold-Rolled Bainitic–Ferritic Steel, 14(2021), 6662.
27. [27] Graux, A.; Cazottes, S.; Castro, D.D.; San-Martín, D.; Capdevila, C.; Cabrera, J.M.; Molas, S.; Schreiber, S.; Mirković, D.; Danoix, F. Design and Development of Complex Phase Steels with Improved Combination of Strength and Stretch-Flangeability, 10(2020), 824.
28. [28] Pütz, F., Shen, F., Könemann, M. The differences of damage initiation and accumulation of DP steels: a numerical and experimental analysis, 226(2020), 1–15.
29. [29] Yun, H. A. N., Kuang, S., Liu, H. S., Jiang, Y. H., & Liu, G. H. Effect of Chromium on Microstructure and Mechanical Properties of Cold Rolled Hot-dip Galvanizing DP450 Steel, 22(2015), 1055–1061.
30. [30] A. Ramazani, Z. Ebrahimi, U. Prahl, Study the effect of martensite banding on the failure initiation in dual-phase steel,Computational Materials Science, 87(2014), 241-247.
31. [31] Chen X, Liang J, Yang D, Hu Z, Xu X, Gu X, Xie G. Effect of Chromium on Microstructure and Mechanical Properties of Hot-Dip Galvanized Dual-Phase (DP980) Steel, 13(2023), 1287.
32. [32] Meyers, M. A., & Chawla, K. K. 2008. Mechanical behavior of materials. Cambridge University Press.
33. [33] Ji Hoon Kim, M.G. Lee, D. Kim, D.K. Matlock, R.H. Wagoner. Hole-expansion formability of dual-phase steels using representative volume element approach with boundary-smoothing technique, 527(2010), 7353-7363.
34. [34] Queiroz, R. R. U., Cunha, F. G. G., & Gonzalez, B. M. Study of dynamic strain aging in dual phase steel. Materials Science and Engineering: A, 543(2012), 84-87.