Impact of the initial microstructure and the loading conditions on the deformation behavior of the Ti17 titanium alloy

Abstract

In this work, the impact of the microstructure and the loading conditions on the mechanical behavior of a brich Ti17 titanium alloy is investigated. For this purpose, two different initial microstructures are considered : (i) a two-phase lamellar a ? b microstructure and (ii) a single-phase equiaxed b-treated microstructure. First, compression tests are performed at different strain rates (from 10 À1 to 10 s-1) and different temperatures (from 25 to 900 C) for both microstructures. Then, optical microscopy, scanning electron microscopy, EBSD and X-ray diffraction analyses of deformed specimens are carried out. Whatever the loading conditions are, the flow stress of the as-received a ? b Ti17 is higher than that of the b-treated Ti17. Also, because of a higher strain-rate sensitivity, the b-treated Ti17 is less prone to shear banding. At low temperatures (i.e., T 450 C), the deformation behavior of both the as-received a ? b and the b-treated Ti17 is controlled by strain hardening. For the b-treated Ti17 alloy, martensitic transformation is systematically detected in this temperature range. The softening behavior of the as-received a ? b Ti17 observed at high temperatures is due to the joint effect of dynamic recrystallization, dynamic transformation , adiabatic heating and morphological texture evolution. For the b-treated Ti17 alloy, when the temperature exceeds 700 C, stressstrain curves display a yield drop phenomenon, which is explained by dynamic recrystallization.

Effect of High Strain Rate on Adiabatic Shearing of α+β Dual-Phase Ti Alloy

“…At the strain rate of 1000 s −1 , multiple deformation mechanisms were comprehensively investigated in Ti-25Nb-3Zr-3Mo-2Sn, presenting the dynamic deformation sequences as {332}<113> and {112}<111> mechanical twining + stress-induced α” and ω phase transformations + dislocation slip at 293K → {332}<113> and {112}<111> mechanical twining + dislocation slip at 573K → dislocation slip only at 873 K [ 29 ]. The softening behavior of dual-phase Ti17 alloy (Ti-5Al-4Cr-4Mo-2Sn-2Zr) at a high temperature is attributed to the combinations of dynamic recrystallization, dynamic transformation, adiabatic heating, and morphological texture evolution [ 30 ]. Instead of thermal softening mechanisms, the microstructure evolutions or transformations play an important role in the initiation of ASB [ 21 , 24 , 31 , 32 , 33 ].…”

A crystal plasticity-based constitutive model for near-β titanium alloys under extreme loading conditions: Application to the Ti17 alloy

“…The experimental procedure used for such tests is briefly described here. A detailed description of the experimental setup can be found in Ben-Boubaker et al (2020).…”

“…For low temperatures (𝑇 ≤ 450 • C), the maximum error between the experimental and numerical curves does not exceed 6%. For temperatures above 700 • C, a yield drop phenomenon, which is attributed to either dynamic recrystallization Ben-Boubaker et al (2020) or the multiplication of mobile dislocations Teixeira et al (2007), is observed. This phenomenon is partly captured by the proposed model.…”

Effect of High Strain Rates on Adiabatic Shear Bands Evolution and Mechanical Performance of Dual-Phase Ti Alloy

“…In order to develop the advanced Ti alloys integrated the damage tolerance and high strength properties, a great amount of efforts have been completed investigating the high-strain rate shear behaviours of α Ti (Shahan and Taheri, 1993;Meyers et al, 1994;Chichili et al, 1998;Yang and Wang, 2006;Wang et al, 2007;Yang et al, 2010;Jiang et al, 2015;Kuang et al, 2017), Ti-6Al-4V alloy (Me-Bar andShechtman, 1983;Grebe et al, 1985;Da Silva and Ramesh, 1997;Lee and Lin, 1998;Timothy and Hutchings, 2013;Sun et al, 2014a;b;Mendoza et al, 2015;Zhou et al, 2017), TC16 (Wang, 2008), near-β Ti5551 (Ran and Chen, 2018) and Ti5553 (Yan and Jin, 2020), β ones (Zhan et al, 2016), α + β dual-phase ones (Yang et al, 2011b;Mantri et al, 2018;Ben Boubaker et al, 2019;Danard et al, 2019;Kloenne et al, 2020;Lee et al, 2020), and so on. It is worth mentioning that the dual-phase materials (Wu et al, 2017;Hao et al, 2021;Zou et al, 2021) always present ultra-strong and ductile behaviors combining the solid solution strengthening, grain refinement effect, and precipitation hardening, which could excellently deal with the planar-defects-dominated plastic deformation behaviors (Hao et al, 2021).…”

“…The traditional wellaccepted thermal-softening mechanism of ASB should be double checked, calling for more research efforts to reveal the microstructure evolutions resulting in the local softening (Guo et al, 2019). Therefore, it is necessary to reveal their corresponding softening mechanisms, including the dynamic recrystallization, dynamic transformation, adiabatic heating, and morphologies texture evolution (Yang and Wang, 2006;Rittel et al, 2008;Osovski et al, 2012;Li et al, 2017;Lieou and Bronkhorst, 2018;Ben Boubaker et al, 2019;Hao et al, 2021).…”