Features of Duplex Microstructural Evolution and Mechanical Behavior in the Titanium Alloy Processed by Equal‐Channel Angular Pressing

Abstract

This report describes a study of the regularities in the kinetics of microstructure evolution and recrystallization processes in the Ti-5.7Al-3.8Mo-1.2Zr-1.3Sn alloy (Russian analogue VT8M-1) during processing by equal-channel angular pressing (ECAP). To produce a duplex (globular-lamellar) structure, the billets are subjected to preliminary heat treatment, including water-quenching from a temperature below the β-transus followed by annealing at 700 С. For the ECAP temperature selection, the deformation behavior of the alloy with a duplex structure is investigated under upsetting in the temperature range of 650-800 С. The evolution of the globular and lamellar fractions is examined during ECAP processing, and an emphasis is placed on the role of phase transformations, dynamic recrystallization, and spheroidization of the α-phase which is realized with increasing accumulated strain when processing by ECAP. It is demonstrated that after 6 ECAP passes an equiaxed ultrafine-grained structure is formed with a mean α-phase grain/subgrain size of %0.6 μm. The investigation includes an examination of the effect of microstructure on the mechanical properties of the alloy.

Architecture and Increased Adhesive Strength of Vacuum‐Plasma Coating on Ultrafine‐Grained Titanium Alloy

“…Previously, such an approach to increasing the grain refinement efficiency during processing was successfully applied to the Ti-6Al-4V alloy. [7] As follows from the SEM data (Figure 1b), RS processing resulted in almost the complete transformation of the alloy VT8M-1 plate component into a globular one. The average size of globular grains of the primary α-phase was about 3 μm.…”

“…The samples from this hard‐to‐deform Ti alloy were subjected to a preliminary HT for the formation of a duplex microstructure consisting of a primary α‐phase in the billet volume of not more than 25% and a thin‐plate α + β structure (Figure a). Previously, such an approach to increasing the grain refinement efficiency during processing was successfully applied to the Ti–6Al–4V alloy …”

“…At the same time, there are currently only a few studies on the properties of vacuum-plasma coatings deposited on the surface of UFG metals and alloys, and it is of particular interest to investigate this problem for the industrial titanium alloy VT8M-1 (Ti-5.7Al-3.8 Mo-1.2Zr-1.3Sn) applied in aircraft engine manufacturing. [4][5][6][7] The aim of this article is the study of the adhesion strength of TiVN protective coating on the selected alloy after the formation of UFG structure in it, using the famous known SPD technique-rotary swaging (RS). [8,9] The titanium alloy VT8M-1 used in this investigation was provided by VSMPO-AVISMA Corporation (Verkhnaya Salda, Russia) with the following composition wt%: Ti-5.7Al-3.8 Mo-1.2Zr-1.3Sn.…”

“…Combining two methods will increase the service reliability of titanium alloy products that must perform in an extreme environment. At the same time, there are currently only a few studies on the properties of vacuum‐plasma coatings deposited on the surface of UFG metals and alloys, and it is of particular interest to investigate this problem for the industrial titanium alloy VT8M‐1 (Ti–5.7Al–3.8 Mo–1.2Zr–1.3Sn) applied in aircraft engine manufacturing . The aim of this article is the study of the adhesion strength of TiVN protective coating on the selected alloy after the formation of UFG structure in it, using the famous known SPD technique—rotary swaging (RS) …”

A Comparison of Warm and Combined Warm and Low‐Temperature Processing Routes for the Equal‐Channel Angular Pressing of Pure Titanium

“…All of these results are consistent and they demonstrate that some additional processing is required after ECAP in CP Ti to achieve the maximum YS. In contrast, high values of the YS may be achieved in appropriate Ti alloys after processing by ECAP without any additional processing: for example, the YS of ≈1134 MPa was reported in a Ti–5.7Al–3.8Mo–1.2Zr–1.3Sn alloy after ECAP processing through two passes using a die with a channel angle of 120° at a temperature of 1023 K …”