the effects of the thermo-mechanical process variables on the microstructure,mechanical properties, and recrystallization behavior of the commercially pure titanium

Commercial pure titanium sheets were thermo-mechanically treated to investigate the effects of the treatment variables on the microstructure, mechanical properties, and recrystallization behavior. the as-received sheets were initially cold-rolled up to different reduction percentages of 60%, 75%, and 90%. then, the cold-rolled samples were annealed at different temperatures of 500°c-700°c, for various time ranges of 5 to 60 minutes. the evolution of the microstructure of the samples was studied using x-ray diffraction analysis and optical microscopy. the hardness of the 90% cold-rolled sample was about 82% higher than that of the as-received sheet. increasing the time and temperature of the annealing process caused a decrease in the microhardness values of the samples. the recrystallization activation energy and avrami’s exponent of the 90% coldrolled sample were calculated as about 179 kj/mol and 0.75, respectively. the results of the uniaxial tensile tests revealed that the cold-rolling process significantly improved the yield strength (ys) and ultimate tensile strength (uts) of the specimens. in the case of the 90% coldrolled sample, these values improved by about 160% and 117% with respect to the as-received metal, respectively. however, the elongation of the cold-rolled samples dropped sharply. moreover, annealing had a positive effect on the elongation of the cold-rolled samples. the uts and elongation percentage of the as-received sheet were 415 mpa and 36.4%, respectively. these values were varied to 558 mpa and 29.15% for the 90% cold-rolled sample annealed at 700°c for 1 h. to study the fracture behavior of the different samples, scanning electron microscopy (sem) was used.