Deformation behaviour of commercially pure titanium during simple hot compression

Commercially pure titanium (CP Ti), grade II, is subjected to hot compression at temperatures ranging from 673 to 973 K with 50 K intervals and strain rates of 0.001, 0.01, 0.1 and 1 s−1 up to 60% height reduction. By analysing work hardening rate vs. flow stress, the deformation behaviour can be divided into three groups, viz. three-stage work hardening, two-stage work hardening and flow softening. By plotting the data in a T vs. logε˙ diagram, the present and previous data fall into three distinct domains which can be separated by two distinct values of the Zener–Hollomon parameter. The microstructure after deformation is characterized by optical microscopy and electron back scattered diffraction. The formation of {101¯1} twins is related to the Zener–Hollomon parameter. Geometric dynamic recrystallization seems most appropriate when describing the grain refinement process of CP Ti during hot compression.