Dependence of Macro- and Micro-Properties on α Plates in Ti-6Al-2Zr-1Mo-1V Alloy with Tri-Modal Microstructure

Abstract

Tri-modal microstructure is often the target microstructure of titanium alloy components. In this study, the parameters, such as volume fraction, size of primary equiaxed α (α p ), secondary lamellar α (α s ) and thin α plates (α t ) in tri-modal microstructure of Ti-6Al-2Zr-1Mo-1V alloy are adjusted by double heat treatment procedures. The properties of these constituent phases and their effect on the macro-properties are then investigated. The results show that the hardness of primary α (α p ) varies slightly with heat treatment routes. The hardness of α plates region including α s and α t increases with increasing α t volume fraction and not with decreasing thickness of α s and α t . Using volume average of the thickness of α s and α t as effective thickness (t eff ), the hardness of α plates region and t eff follow the Hall-Petch relationship. Meanwhile, as α t volume fraction increases, colony structure of α s is gradually destroyed, which makes each α s have large deformation degree by multiple directions slip. When volume fraction ratio of α p , α s and α t is about 1:1:1, α p and α s can undergo relatively large deformation and α t can contribute relatively large strength to the alloy and therefore the alloy has both good strength and ductility.

Complexity and Anisotropy of Plastic Flow of α-Ti Probed by Acoustic Emission and Local Extensometry

“…This level of consideration is missing in model [ 12 ] and, more generally, in the models based on the homogenization approach, and will present a challenge for future investigations. It is particularly interesting in view of the recent technological developments which show a tendency to fabricate Ti and Ti alloys with complex microstructures containing micro- and nano-size elements, e.g., submicron grains [ 34 , 35 , 36 ].…”

Theoretical Evaluation of Strengthening Ability of Phase Interfaces in Lamellar Ti Alloys

“…Finally, f α/β = 0%–100% corresponds to the k values produced by the comprehensive strengthening effect of α p / α s and α s / β interface in the bi‐lamellar Ti alloys. Such as in literature, [ 43 ] the trimodal microstructure consisted of equiaxed α p , lamellar α s , and transformed β matrix with thin α plates ( α t ) and retained β phase is obtained by double heat treatment procedures. The area other than equiaxed α p is called α plates region, which includes α s , α t , and retained β phases.…”

“…In literature, [ 43 ] the fraction of α s phase relative to the α plates region is 6.8%, 36.9%, and 66.4%, the fraction of α t phase relative to the α plates region is 71.8%, 38.9%, and 8.8%, the width of α s phase is 1.36, 1.1, and 0.88 μm and the width of α t phase is 0.41, 0.39, and 0.38 μm for different heat‐treated samples shown in Table S4, Supporting Information. Then, the average fractions of (similar to in bi‐lamellar structure) is 65.1%.…”

Effects of Loading Frequency and Specimen Geometry on High Cycle and Very High Cycle Fatigue Life of a High Strength Titanium Alloy

“…Titanium alloys have excellent performance such as high fatigue resistance, high corrosion resistance, and high temperature resistance, and have been widely used in deep-sea equipment and aviation industries. Many studies have been performed for the microstructural, mechanical, and fatigue properties of titanium alloys [ 18 , 19 , 20 ]. Ti-6Al-2Sn-2Zr-3Mo-X is a new type of titanium alloy with high yield strength and high fracture toughness, which could be used in structural components in deep-sea equipment such as submersibles.…”