Metallographic Atlas of Titanium and Titanium Alloys

Metallographic Atlas of Titanium and Titanium Alloys--II

Ti-3Al-2. 5V(Ti Gr.9) Titanium Alloy

Ti-3Al-2.5V(Ti Gr.9) Titanium alloy is nearly α titanium alloy (Chinese brand TA18). The alloy, developed in the United States, is a medium strength titanium alloy between pure titanium and Ti-6Al-4V(Ti Gr.5) titanium alloy. Its characteristic is much better than Ti-6Al-4V(Ti Gr.5) titanium alloy cold processing, suitable for cold rolling into tubes, sheets, and other products. Its phase transition point is 935℃. The mechanical properties of the alloy are shown in Table 2-1, and the microstructure is shown in Picture 2-1~ 2-6.

Table 2-1 Mechanical Properties of Ti-3Al-2.5V(Ti Gr.9) Titanium Alloy pipes (730℃/1h air cooling)

Picture 2-1: After 950℃ water quenching for 30min, Ti-3Al-2.5V(Ti Gr.9) Titanium alloy has 

β-transformed structure completely, and there are large α-sheets (bright) in the crystal.

Picture 2-2: after water quenching treatment at 920℃/30min, The equiaxed primary 

α (bright) + lamellar β transformation structure (dark) of Ti-3Al-2.5V(Ti Gr.9) Titanium alloy 

Picture 2-3: Ti-3Al-2.5V(Ti Gr.9) titanium alloy after 900℃/30min water quenching treatment,

Equiaxed primary α (bright) + lamellar β transformation tissue (dark)

Picture 2-4: Ti-3Al-2.5V(Ti Gr.9) titanium alloy after 800℃/30min water quenching treatment,

Incomplete recrystallized structure, equiaxed α+ intercrystalline β

Picture 2-5: Cold rolled Ti-3Al-2.5V(Ti Gr.9) titanium alloy tubes were treated at 700℃/60min,

Vacuum annealing treatment (longitudinal) elongated α+ intergranular β

Picture 2-6: Cold rolled Ti-3Al-2.5V(Ti Gr.9) titanium alloy tubes were treated by vacuum annealing at 800℃/60min (longitudinal),

Equiaxed α+ intergranular β+ annealing twins