The recrystallization behaviour of CP-titanium

In the present investigation, recrystallization of Grade-2 quality commercial purity titanium (CP-Ti) has been studied. CP-Ti was received as 4 mm thick plate having hardness of 202 HV_0.3. Upon rolling about 55, 70 and 85 % at room temperature, the hardness increased to 268, 276 and 283 HV _0.3, respectively. Cold rolled samples were then subjected to isothermal annealing in salt bath at 550-700°C. After measuring hardness, recrystallization curves were plotted for each annealing temperature. Recovery region was not clearly visible on the recrystallization curves. Heavily cold worked samples were soften rapidly and reached to the grain growth region at shorter annealing times. According to Arrhenius plot, recrystallization activation energy of CP-Ti was calculated in between 89,5 and 78,6 kJ/mol. The higher the cold working, the lower is the recrystallization activation energy.