226 Prakt. Met. Sonderband 38 (2006) 
The fine a phase was transformed into the B phase during the heat treatment and after 3. 
reaching the holding temperature the content of primary a phase at 768°C and 788°C was 
36% and 30% respectively. The alpha content decreased to 13% at 768°C and 5.7% at Th 
788°C after 5 minutes of holding time, and there was no indication of more dissolution of va 
alpha phase by increasing time at temperature (Fig. 4a)). Fig. 4b) shows the variation of gi\ 
im? . pe 
the area and shape factor (defined as SF = La of alpha grains. The area of the alpha 1s 
Area 
grains was also almost constant when the phase equilibrium was reached, but the shape 
factor tended to increase with time and temperature. The mean values of maximum and 
minimum length are around 3uym and 1.1um at 768°C and near 2.6um and 1um at 788°C. 
aE 768°C UT ec 788°C “9 
“ CL ® Area 
a 788°C 2 Oo O Shape Factor 10.8 
£ 30 . 
Peas] — 6H A © [0.6 5 
20] 5 s i 
g 4 04 8 
+ 154 2 N . | 5 
10° I 02 
z a B&B . 
5 ° a 
U Arey UA] 0.0 Fi 
0 5 10 15 20 25 30 35 b) 0 5 10 15 20 25 30 35 et 
a) Holding Time [min] Time [min] 
Fig 4. a) Alpha phase equilibrium of the as received condition after heating up to 768°C Fi 
and 788°C. b) Variation of the area and the shape factor of the alpha phase Tt 
3.2 FLOW CURVES in 
Fig. 5 shows the flow behaviour of the Ti-10-2-3 at 768°C and 788°C at constant strain 
rates of 0.01, 0.1 and 1s™. For both temperatures and after an initial sharp peak, the 
specimens deformed at 0.1 and 1s” presented a softening behaviour, while at 0.01s™, a 
steady-state flow can be observed. There was no substantial difference between both 
temperatures at high strain rate (1s). The stress increased with increasing the strain rate 
and at slow strain rates with decreasing temperature. 
175 + —— 175 . - 
i ACC k 788°C 
150. 150 {* 
125 = 125 
Ei Cr. 
= sol = 100 us 5 
' @ AHRENS TEE RE GR == A 
. 75.1 2 75 = 
In 5 on 
3 J “ETE © IT C 
= 50 2 50 ii gs TUT - S| 
—A— 15 am Lima 1 57 
25 —o— 0.15" 25 —0— 0.15" 
3 —0=— 0.015" 0 | —0— 0.015" 1 
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0° a 
a) b} 3 
True Strain True Strain 
Fig 5.Flow Curves at different strain rates at: a) 768°C and b) 788°C