Flow Localization Modelling in Ti Alloys and Ti Matrix Composites

Abstract:

Titanium-based alloys are commonly applied to aerospace, medicine and energy due mainly to their high specific mechanical properties and high corrosion resistance. Reinforcement with particles further improves their specific strength and stiffness. In previous studies, the hot formability of both unreinforced Ti6Al6V2Sn alloy, and reinforced with 12%vol of TiC particles was analyzed by hot compression tests carried out by means of Gleeble device and metallography. It was observed that the hot workability of these materials is limited at given forming conditions by non-desirable shear bands, voids, as well as micro- and macro cracks, especially in the composite. In this work, damage during hot deformation is predicted by damage models coupled to FEM. Therefore, the flow localization parameter α described by thermal and microstructural softening and the strain rate sensitivity are computed and implemented in DEFORM^TM 2D to describe the localization of the plastic flow. The results show intense flow localization as a combination of low dynamic restoration (given by small m values) and temperature gradient. The damage analysis combined with the Cockcroft and Latham continuum cumulative stress model.

• Periodical: Key Engineering Materials (Volumes 651-653)
• Pages: 3-8
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.651-653.3
• Online since: July 2015
• Authors: Dilek Halici*, Maria Cecilia Poletti
• Keywords: Ductile Damage, FEM, Hot Deformation, Titanium Alloys, Titanium Matrix Composites

References

[1] M. Peters and C. Leyens, Titanium and Titanium Alloys. Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA, (2002).

[2] C. Poletti, A. Merstallinger, T. Schubert, W. Marketz, and H.P. Degischer, Wear and Friction Coefficient of Particle Reinforced Ti-Alloys, Materwiss. Werksttech. 35 (2004) 741–749.

DOI: 10.1002/mawe.200400818

[3] R. Boyer, E.W. Collings, and G. Welsch, Materials Properties Handbook: Titanium Alloys. Materials Park, Ohio ASM International, (2007).

[4] C. Poletti, H.P. Degischer, S. Kremmer and W. Marketz, Processing maps of Ti662 unreinforced and reinforced with TiC particles according to dynamic models, Mater. Sci. Eng. A 486 (2008) 127–137.

DOI: 10.1016/j.msea.2007.08.077

[5] S.L. Semiatin and J.J. Jonas, Formability and Workability of Metals, Plastic Instability and Flow Localization. Ohio: American Society for Metals, Metals Park, (1984).

[6] C. Poletti, F. Warchomicka, S. Kremmer, M. Stockinger and H.P. Degischer, Local deformation of Ti alloys and Ti matrix composites, Proceeding of Ti-2007, The 11th World Conference on Titanum 1 (2007) 595–598.

[7] S.L. Semiatin, V. Seetharaman, and I. Weiss, Hot workability of titanium and titanium aluminide alloys—an overview, Mater. Sci. Eng. A 243 (1998) 1–24.

DOI: 10.1016/s0921-5093(97)00776-4

[8] A. Considère, Mémoire sur l'Emploi du Fer et de l'Acier dans les ConstructionsNo Title. Annales des Ponts et Chaussées 1885, p.874–775.

DOI: 10.1016/s0152-9668(02)80003-1

[9] M. Dikovits, C. Poletti, and F. Warchomicka, Deformation Mechanisms in the Near-β Titanium Alloy Ti-55531, Metall. Mater. Trans. A 45 (2013) 1586–1596.

DOI: 10.1007/s11661-013-2073-4

[10] M.G. Cockcroft and D.J. Latham, Ductility and the Workability of Metals, J. Inst. Met. 96 (1968) 33–39.

[11] C.M. Sellars and W.J.M. Tegart, Hot Workability, Int. Metall. Rev. 17 (1972) 1–24.