Effect of oxygen and iron impurities on the hot deformation behavior of CP-Ti at intermediate temperatures

Deformation behavior of CP-Ti was studied at intermediate temperatures, ranging from 300 to 600 degreesC, by compression testing at various strain rates, from 10(-3)/s to 10/s, using a Thermecmaster. The deformation behavior was found to be abnormal at a strain rate slower than 10/s, resulting from the dynamic strain aging associated primarily with oxygen and iron impurity. The dynamic strain aging associated with oxygen was little sensitive to the concentration of oxygen, and it tended to dominate under the deformation conditions of a slow strain rate and a high temperature. The dynamic strain aging due to iron was sensitive to the iron concentration, and the peak temperature tended to shift toward a slightly higher temperature in iron-rich grade-4 CP-Ti, simultaneously, a new source for dynamic strain aging appeared, particularly under the deformation conditions of a high strain rate and a low temperature. This new source was believed to be the iron diffusing via a divacancy mechanism.