A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 1 1 8 Due to the debit in mechanical properties and service performance associated with MTRs, a number of attempts have been made to lessen their severity. Various techniques include breakdownof the colonymicrostructure via low-temperature superplastic forging, multistep processing at successively lower temperatures, and multi-axial forging[18-20]. For example, a change in strain path involving redundant work can be effective in eliminating MTRs in forgings[14]. The usefulness of a strain-path change such as elongation followed by compression was also recently suggested using crystal plasticity finite element method simulations for Ti-6242[21]. Finally, an approach consisting of α/β hot working of workpieces that have been β annealed and water quenched to produce a basketweave α microstructure (i.e., multiple variants at any given location) has been suggested[22]. However, this specific method is likely only suitable for section sizes in which the basketweave microstructure can be developed during water quenching. Part II of this series will further elaborate on the effects of microtexture on deformation behavior and will be available in a future issue of AM&P. Acknowledgments The authors wish to extend their gratitude to the following collaborators for many useful discussions related to microtexture: T.R. Bieler, T.F. Broderick, S. Daly, M.G. Glavicic, P.D. Nicolaou, V. Venkatesh, J.C. Williams, and A. Woodfield. Michelle Harr wishes to acknowledge the support of the National Science Foundation Graduate Research Fellowship under Grant No. 1256260 DGE and the Air Force Research Labs under Contract #FA8650-16-C-5235 during the completion of this work. ~AM&P For more information: Adam Pilchak, Air Force Research Laboratory, AFRL/ RXCM, Wright-Patterson Air Force Base, Ohio, 45433, adam.pilchak.1@us.af.mil. References 1. A.P. Woodfield, et al., Effect of Microstructure on Dwell Fatigue Be- havior of Ti-6242, Titanium ’95: Science and Technology, p 1116-1123, 1995. 2. France-BEA, Accident to the AIRBUS A380-861 Equipped with Engine Alliance GP7270 Engines Registered F-HPJE Operated by Air France on 30 September 2017 in Cruise over Greenland (Denmark), 2020. 3. L. Germain, et al., Analysis of Sharp Microtexture Heterogeneities in a Bimodal IMI 834 Billet, Acta Mater., Vol 53, p 3535-3543, 2005. 4. I. Bantounas, D. Dye, and T.C. Lindley, The Role of Microtexture on the Faceted Fracture Morphology in Ti6Al-4V Subjected to High-Cycle Fatigue, Acta Mater., Vol 58, p 3908-3918, 2010. 5. J.L.W. Warwick, et al., In Situ Observation of Texture and Microstructure Evolution During Rolling and Globularization of Ti-6Al-4V, Acta Mater., Vol 61, p 1603-1615, 2013. 6. S.L. Semiatin, An Overview of the Thermomechanical Processing of α/β Titanium Alloys: Current Status and Future Research Opportunities, Metall. Mater. Trans. A, Vol 51, p 2593-2625, 2020. 7. T.R. Bieler and S.L. Semiatin, The Origins of Heterogeneous Deformation During Primary Hot Working of Ti-6Al4V, Int. J. Plast., Vol 18, p 1165-1189, 2002. 8. S.L. Semiatin, et al., Cavitation and Failure During Hot Forging of Ti-6Al-4V, Metall. Mater. Trans. A, Vol 30, p 14111424, 1999. 9. T.R. Bieler, P.D. Nicolaou, and S.L. Semiatin, An Experimental and Theoretical Investigation of the Effect of Local Colony Orientations and Misorientation on Cavitation During Hot Working of Ti-6Al-4V, Metall. Mater. Trans. A, Vol 36, p 129-140, 2005. 10. T.R. Bieler, M.G. Glavicic, and S.L. Semiatin, Using OIM to Investigate the Microstructural Evolution of Ti-6Ai-4V, JOM, Vol 54, p 31-36, 2002. 11. P.D. Nicolaou, J.D. Miller, and S.L. Semiatin, Cavitation During Hot-Torsion Testing of Ti-6Al-4V, Metall. Mater. Trans. A, Vol 36, p 3461-3470, 2005. 12. P.D. Nicolaou and S.L. Semiatin, An Analysis of Cavity Growth During OpenDie Hot Forging of Ti-6Al-4V, Metall. Mater. Trans. A, Vol 36, p 1567-1574, 2005. 13. A.L. Pilchak, et al., Characterization of Microstructure, Texture, and Mi- crotexture in Near-Alpha Titanium Mill Products, Metall. Mater. Trans. A, Vol 44, p 4881-4890, 2013. 14. N. Gey, et al., Texture and Microtexture Variations in a Near-Α Titanium Forged Disk of Bimodal Microstructure, Acta Mater., Vol 60, p 2647-2655, 2012. 15. M.D. Gorman, A.P. Woodfield, and B.A. Link, US Patent 6,284,070, 2001. 16. B.A. Begley, et al., Prediction of Relative Globularization Rates in α + β Titanium Alloys as a Function of Initial Crystal Orientation, J. Mater. Res., Vol 35, p 1113-1120, 2020. 17. A.L. Pilchak, G.A. Sargent, and S.L. Semiatin, Early Stages of Microstructure and Texture Evolution During Beta Annealing of Ti-6Al-4V, Metall. Mater. Trans. A, Vol 49, p 908-919, 2017. 18. G.A. Salishchev, O.R. Valiakhmetov, and R.M. Galeyev, Formation of Sub- microcrystalline Structure in the Titanium Alloy VT8 and its Influence on Mechanical Properties, J. Mater. Sci., Vol 28, p 2898-2902, 1993. 19. G.A. Salishchev, S.Y. Mironov, and S.V. Zherebtsov, Mechanisms of Submicrocrystalline Structure Forma- tion in Titanium and Two-Phase Titanium Alloy During Warm Severe Processing, Rev. Adv. Mater., Vol 11, p 152-158, 2006. 20. G.A. Salishchev, et al., Development of Ti-6Al-4V Sheet with Low Temper- ature Superplastic Properties, J. Mater. Process. Technol., Vol 116, p 265-268, 2001. 21. R. Ma, et al., Modeling the Evolution of Microtextured Regions During α/β Processing Using the Crystal Plasticity Finite Element Method, Int. J. Plast., Vol 107, p 189-206, 2018. 22. B.P. Bewlay, et al., US Patent 6,387,197, 2002.
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