Effects of Testing Method on Stretch-Flangeability of Dual-Phase 980/1180 Steel Grades
- 24 Downloads
Challenging fuel economy and safety standards in the automotive industry have led to the need for materials with higher strength while maintaining levels of formability that meet component manufacturing requirements. Advanced high-strength steels, such as dual-phase steels with tensile strengths of 980 MPa and 1180 MPa, are of interest to address this need. Increasing the strength of these materials typically comes at the expense of ductility, which may result in problems when stamping parts with trimmed or sheared edges, as cracking at the sheared edge may occur at lower strains. Here, hole expansion tests were performed with different punch geometries (conical and flat-bottom) and different edge conditions (sheared and machined) to understand the effects of testing conditions on performance, and these results are discussed in terms of mechanical properties and microstructures.
Baosteel are acknowledged for providing the experimental material. Hole expansion testing was performed at ArcelorMittal (East Chicago) and AK Steel (Middletown, OH). Dr. Kavesary Raghavan and Dr. Mai Huang are acknowledged for assisting with the testing. The sponsors of the Advanced Steel Processing and Products Research Center at Colorado School of Mines are gratefully acknowledged for their support and funding.
- 1.United States Department of Transporation, “Corporate Average Fuel Economy”. http://www.nhtsa.gov/laws-regulations/corporate-average-fuel-economy. Accessed 25 January 2017.
- 2.O. Bouaziz, H. Zurob, and M. Huang, Steel Res. Int. 84, 937 (2013).Google Scholar
- 3.M.Y. Demeri, ASM Handbook, vol. 14B (Materials Park: ASM International, 1996), p. 530.Google Scholar
- 14.A. Karelova, C. Krempaszky, E. Werner, P. Tsipouridis, T. Hebesberger, and A. Pichler, Steel Res. Int. 80, 71 (2009).Google Scholar
- 18.P. Larour, J. Freudenthaler, A. Grunsteidl, and K. Wang, IDDRG Conf. Proc. 188 (2014).Google Scholar
- 19.E. Iizuka, M. Urabe, Y. Yamasaki, and J. Hiramoto, Phys.: Conf. Ser. 896, 012008 (2017).Google Scholar
- 21.M. Miura, M. Nakaya, and Y. Mukai, “Cold-rolled, 980 MPa Grade Steel-sheets with Excellent Elongation and Stretch-flangeability,” http://www.kobelco.co.jp/english//ktr/pdf/ktr_28/008-012.pdf. Accessed 15 Dec 2017.
- 22.ASTM E562-11, Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count (2011).Google Scholar
- 23.M. Madrid, C.J. Van Tyne, and K. Clarke, in MS&T conference proceedings (2017), p. 1302.Google Scholar
- 28.S. Sadagopan and D. Urban, Formability Characterization of a New Generation of High Strength Steels. http://www.steeltrp.com/finalreports/finalreports/0012NonPropFinalReport.pdf Accessed 14 Nov 2017.
- 29.X. Jin, L. Want, and J.G. Speer, in ISAS 2013 (2013), p. 60.Google Scholar