Microstructure of the Advanced Titanium Alloy VT8M-1 Subjected to Rotary Swaging

Area of Science:

• Materials Science
• Metallurgy
• Physical Metallurgy

Background:

• Advanced titanium alloys like VT8M-1 offer enhanced heat resistance, positioning them as potential replacements for Ti-6Al-4V.
• Understanding microstructural evolution during processing is crucial for optimizing alloy performance.

Purpose of the Study:

• To investigate the microstructural behavior of Ti-5.7Al-3.8Mo-1.2Zr-1.3Sn-0.15Si (VT8M-1) alloy during rotary swaging (RS).
• To compare the microstructural outcomes of RS with those of equal-channel angular pressing (ECAP).

Main Methods:

• Rotary swaging (RS) was applied to the VT8M-1 alloy.
• Electron Backscatter Diffraction (EBSD) was used to analyze microstructural changes.
• Transmission Electron Microscopy (TEM) was employed to examine particle characteristics.

Main Results:

• RS led to continuous dynamic recrystallization, significantly increasing low-angle boundary density (from 0.38 to 1.21 µm⁻¹).
• Spheroidization of the lamellar (α + β) phase was incomplete, with average globular particle size of 0.3 μm (TEM).
• RS resulted in a higher density of low- and high-angle boundaries compared to ECAP at similar strain levels.

Conclusions:

• RS promotes a distinct microstructure characterized by a high density of low-angle boundaries.
• The microstructural evolution under RS differs significantly from ECAP, particularly in phase globularization.
• These findings aid in predicting alloy microstructure for producing long rods for forging.