**11. Conclusions**

Metastable beta titanium alloys have exclusive properties like the ease of fabrication, excellent biocompatibility, and good corrosion resistance. Hence, a steady progress has been there in the application of these alloys in aerospace industries and other high-technology industrial segments. Metastable beta titanium alloys are evolving as a potential candidate even for biomedical and automotive industries. As the βtrans temperature of the metastable beta alloys is significantly lower when compared to α and α + β alloys, the cost of processing is considerably lower. Possibility of tailoring the properties through heat treatments based on the requirement is an important and outstanding property of the metastable beta titanium alloys. However, sound knowledge in the process-structure–property correlation is required. Heat treatments should be designed appropriately to avoid embrittlement due to intermediate phases such as ɷ and premature failure due to the grain boundary alpha (GBα). In this chapter, we have attempted to provide insights into the heat treatment of metastable beta titanium alloys and optimization of the heat treatment parameters to achieve maximized material performance under monotonic and cyclic loading conditions.

**Author details**

Tamilnadu, India

**215**

Sudhagara Rajan Soundararajan1,2, Jithin Vishnu3

*Heat Treatment of Metastable Beta Titanium Alloys DOI: http://dx.doi.org/10.5772/intechopen.92301*

\*

1 School of Mechanical Engineering, Vellore Institute of Technology (VIT), Vellore,

2 International Institute for Aerospace Engineering and Management (IIAEM), Jain

3 Centre for Biomaterials, Cellular and Molecular Theranostics, Vellore Institute of

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

and Nageswara Rao Muktinutalapati<sup>1</sup>

University, Bangalore, Karnataka, India

provided the original work is properly cited.

Technology (VIT), Vellore, Tamilnadu, India

\*Address all correspondence to: muktinutala@gmail.com

, Geetha Manivasagam1,3

## **Acknowledgements**

The authors would like to express their gratitude to the Management of Vellore Institute of Technology (VIT)—Vellore campus, Tamil Nadu, India for allowing us to submit this manuscript.

*Heat Treatment of Metastable Beta Titanium Alloys DOI: http://dx.doi.org/10.5772/intechopen.92301*

in strength. Compared to the low-strength solution-treated conditions, cold working/oxygen content increase/subsequent aging can result in strengthening associated with ω and/or α precipitation. For example, aging of low-modulus biomedical ternary alloys (Ti-35Nb-7Zr-5Ta and Ti-29Nb-13Ta-4.6Zr) in the temperature range of 300–400°C induced ω, 400–475°C ω-α mixture, and high temperature aging above 475°C revealed α precipitation without any ω [67, 68]. It should also be taken in to account that an increased oxygen content in these alloys suppressed ω

Heat treatment of newly designed Sn-based β titanium alloys (Ti-32Nb-2Sn and Ti-32Nb-4Sn) exhibited a single β phase microstructure after solution treatment at 950°C for 0.5 h followed by quenching; subsequent aging resulted in alpha phase precipitation [69]. Higher aspect ratio of precipitated alpha led to age hardening after aging at 500°C for 6 h; aging at 600°C, on the other hand, delitioriosly affected mechanical properties due to matrix softening and relatively coarser alpha precipitates. The presence of Sn even in smaller amounts can suppress the <sup>ω</sup>/α″ precipitation. The abrasion resistance of Ti-10V-1Fe-3Al (βtransus = 830°C) and Ti-10V-2Cr-3Al (βtransus = 830°C) was investigated under different microstructures established by various heat treatments [70]. α + β solution treatment resulted in near spherical or rod-like α, β annealing led to metastable β grains and acicular martensite phase, β + (α + β) produced flake α phase or Widmanstatten α phase and aging at a low and medium temperatures generated high density of nano ω phase precipitates. This study concluded that a dual phase mixture of β and flake-shaped alpha is an appro-

Metastable beta titanium alloys have exclusive properties like the ease of fabrication, excellent biocompatibility, and good corrosion resistance. Hence, a steady progress has been there in the application of these alloys in aerospace industries and other high-technology industrial segments. Metastable beta titanium alloys are evolving as a potential candidate even for biomedical and automotive industries. As the βtrans temperature of the metastable beta alloys is significantly lower when compared to α and α + β alloys, the cost of processing is considerably lower.

Possibility of tailoring the properties through heat treatments based on the requirement is an important and outstanding property of the metastable beta titanium alloys. However, sound knowledge in the process-structure–property correlation is required. Heat treatments should be designed appropriately to avoid embrittlement

The authors would like to express their gratitude to the Management of Vellore Institute of Technology (VIT)—Vellore campus, Tamil Nadu, India for allowing us

due to intermediate phases such as ɷ and premature failure due to the grain boundary alpha (GBα). In this chapter, we have attempted to provide insights into the heat treatment of metastable beta titanium alloys and optimization of the heat treatment parameters to achieve maximized material performance under mono-

formation while promoting α precipitation.

*Welding - Modern Topics*

**11. Conclusions**

tonic and cyclic loading conditions.

**Acknowledgements**

to submit this manuscript.

**214**

priate microstructure for improving the abrasion resistance.
