Plastic Localization Phenomena in a Mn-Alloyed Austenitic Steel
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A 0.5 wt pct C, 22 wt pct Mn austenitic steel, recently proposed for fabricating automotive body structures by cold sheet forming, exhibits plastic localizations (PLs) during uniaxial tensile tests, yet showing a favorable overall strength and ductility. No localization happens during biaxial Erichsen cupping tests. Full-thickness tensile and Erichsen specimens, cut from as-produced steel sheets, were polished and tested at different strain rates. During the tensile tests, the PL phenomena consist first of macroscopic deformation bands traveling along the tensile axis, and then of a series of successive stationary deformation bands, each adjacent to the preceding ones; both types of bands involve the full specimen width and yield a macroscopically observable surface relief. No comparable surface relief was observed during the standard Erichsen tests. Because the stress state is known to influence PL phenomena, reduced-width Erichsen tests were performed on polished sheet specimens, in order to explore the transition from biaxial to uniaxial loading; surface relief lines were observed on a 20-mm-wide specimen, but not on wider ones.
KeywordsCrosshead Speed Stack Fault Energy Surface Relief Dynamic Strain Aging Plastic Instability
ArcelorMittal steelwork for steel procurement. P. Iulita, Fiat Auto Engineering & Design, for the SEM microstructural analysis. C. Pozzi, Politecnico di Torino, for the X-ray analyses. G.M.M. Mortarino, Politecnico di Torino, for collaboration in tensile testing and for useful discussion.
- 1.O. Grässel and G. Frommeyer: Mater. Sci. Technol., 1998, vol. 14, pp. 1213–16.Google Scholar
- 4.S. Vercammen, B. Blanpain, B.C.D. Cooman, and P. Wollants: Acta Metall., 2004, vol. 52, pp. 2005–12.Google Scholar
- 5.O. Bouaziz and N. Guelton: Mater. Sci. Eng. A, 2001, vols. 319–321, pp. 246–49.Google Scholar
- 6.S. Allain, J.P. Chateau, and O. Bouaziz: Mater. Sci. Eng. A, 2004, vols. 387–389, pp. 143–47.Google Scholar
- 7.S. Allain, J.P. Chateau, and O. Bouaziz: Steel Res., 2002, vol. 73, pp. 299–302.Google Scholar
- 8.D. Cornette, P. Cugy, A. Hildenbrand, Bouzekri, and G. Lovato: Rev. Metall., 2005, Dec., pp. 905–18.Google Scholar
- 10.J.K. Kim, L. Chen, H.S. Kim, S.K. Kim, G.S. Kim, Y. Estrin, and B.C. De Cooman: Steel Res. Int., 2009, vol. 80, pp. 493–98.Google Scholar
- 14.G.V. Raynor and V.G. Rivlin: Phase Equilibria in Iron Ternary Alloys, The Institute of Metals, London, 1988, pp. 168–76.Google Scholar
- 17.J.W. Spretnak and D. Firrao: Metall. Ital., 1980, vol. 72, pp. 525–34.Google Scholar