A Study of High Temperature Viscoplastic Deformation of Beta Titanium Alloy Considering Yield-Point Phenomena

Abstract:

In this paper, the high temperature, deformation behaviour of beta titanium alloy Ti-20V-4Al-1Sn sheet is studied by performing uniaxial tension experiments at three different strain rates at high temperatures of 700°C, 750°C and 800°C. The stress-strain curves for these temperatures show strain rate sensitivity, yield point phenomena and continuous flow, softening patterns. Microstructures of deformed specimens at several representative deformation stages and different strain rates are studied using an optical microscope. Dynamic recovery does not occur at the early stage of deformation including the yield-point and the subsequent yield drop regime, but it is activated at a large deformation stage, where it is affected by both strain rate and strain. A viscoplastic, constitutive model, based on the assumption of rapid dislocation multiplication, is proposed to describe such high temperature, yield-point phenomena. In this modelling, the softening effect due to dynamic recovery is also considered. The stress-strain responses, predicted by the constitutive model, well capture the yield-point phenomena, strain rate sensitivity and subsequent continuous flow, softening behaviour of the beta titanium alloy.

• Periodical: Key Engineering Materials (Volumes 410-411)
• Pages: 177-185
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.410-411.177
• Online since: March 2009
• Authors: Xiao Teng Wang, H. Hamasaki, M. Yamamura, R. Yamauchi, Takashi Maeda, Yoshihisa Shirai, Fusahito Yoshida
• Keywords: High-Temperature, Titanium (Ti), Viscoplastic Constitutive Model, Yield-Point

References

[1] R. Srinivasan: Yield points during the high temperature deformation of Ti-15V-3Al-3Cr-3Sn alloy. Scripta. et Mater. Vol. 27 (1992), p.925.

DOI: 10.1016/0956-716x(92)90418-e

[2] M. N. Vijayshankar and S. Ankem: High temperature tensile deformation behaviour of β-Ti alloys. Mater. Sci. Eng. Vol. 129A(1990), p.229.

[3] P. Griffiths and C. Hammond: Superplasticity in large grained materials. Acta Metall. Vol. 20 (1972), p.935.

DOI: 10.1016/0001-6160(72)90087-9

[4] T. Furuhara, B. Poorganji, H. Abe and T. Maki: Dynamic recovery and recrystallisation in titanium alloys by hot deformation. JOM Vol. 59 (2007), p.64.

DOI: 10.1007/s11837-007-0013-8

[5] G. C. Morgan, and C. Hammond: Superplastic deformation properties of β-Ti alloys. Mater. Sci. Eng. Vol. 86(1987), p.159.

[6] V. V. Balasubrahmanyam and Y. V. R. K. Prasad: Deformation of beta titanium alloy Ti-10V-4. 5Fe-1. 5Al in hot upset forging. Mater. Sci. Eng. Vol. 336A(2002), p.150.

DOI: 10.1016/s0921-5093(01)01982-7

[7] I. Philippart and H. J. Rack: High temperature dynamic yielding in metastable Ti-6. 8Mo- 4. 5Fe-1. 5Al. Mater. Sci. Eng. Vol. 243 A(1998), p.196.

DOI: 10.1016/s0921-5093(97)00800-9

[8] A. H. Cottrell and B. A. Bilby: Dislocation theory of yielding and strain ageing of iron. Proc. Phys. Soc. Vol. 62 A(1949), p.49.

DOI: 10.1088/0370-1298/62/1/308

[9] J. J. Gilman: Dislocation Sources in Crystals. J. Appl. Phys. Vol. 30(1957), p.1584.

[10] W. G. Johnston and J. J. Gilman: Dislocation Velocities, Dislocation Densities, and Plastic Flow in Lithium Fluoride Crystals. J. Appl. Phys. Vol. 30 (1957), p.129.

DOI: 10.1063/1.1735121

[11] I. Weiss and S. L. Semiatin: Thermomechanical processing of beta titanium alloys-an overview. Mater. Sci. Eng. Vol. 243A(1998), p.46.

[12] I. Philippart and H. J. Rack: High temperature, high strain deformation behaviour of Ti-6. 8Mo-4. 5Fe-1. 5Al. Mater. Sci. Eng. Vol. 243 A(1998), p.253.

[13] S. L. Semiatin, et al: Self-consistent modelling of the flow behaviour of wrought alpha/beta titanium alloys under isothermal and nonisothermal hot-working conditions. Metall. Mater. Trans. Vol. 33 A(2002), p.2719.

DOI: 10.1007/s11661-002-0394-9

[14] S. Nemat-Nasser, W. G. Guo and J. Y. Cheng: Mechanical properties and deformation mechanisms of a commercially pure titanium . Acta Mater. Vol. 47(1999), p.3705.

DOI: 10.1016/s1359-6454(99)00203-7

[15] D. François, A. Pineau and A. Zaoui: Mechanical of Materials, Vol. 1: Elasticity and Plasticity ( Kluwer Academic Publishers, Netherland 1998).

[16] G. T. Hahn, G. T.: A model for yielding with special reference to the yield-point phenomena of iron and related BCC metals. Acta Metall. Vol. 10 (1962), p.727.

DOI: 10.1016/0001-6160(62)90041-x

[17] S. Kohda: Introduction to Metal Physics (Corona Publishing Inc, Tokyo 1973).

[18] F. Yoshida: A constitutive model of cyclic plasticity. Int. J. Plastic. Vol. 16 (2000), p.359.

[19] F. Yoshida, Y. Kaneda and S. Yamamoto: plasticity model describing yield-point phenomena of steels and its application to FE simulation of temper rolling. Int. J. Plastic. Vol. 24 (2008), p.1792.

DOI: 10.1016/j.ijplas.2008.05.004

[20] H. B. Sun, et al: Effect of strain rate on Lüders band propagating velocity and Lüders strain for annealed mild steel under uniaxial tension. Mater. Lett. Vol. 57 (2003) , p.4535.

DOI: 10.1016/s0167-577x(03)00358-6

[21] H. B. Sun, et al: Finite element simulation on the propagation of Luders band and effect of stress concentration. Mater. Lett. Vol. 57 (2003), p.3206.

[22] J. L. Chaboche: Constitutive equations for cyclic plasticity and cyclic viscoplasticity. Int. J. Plastic. Vol. 5 (1989), p.247.

DOI: 10.1016/0749-6419(89)90015-6