Effect of cold work on recrystallization behavior and grain size distribution in titanium

Abstract

The effect of cold work in the range of 21.9 pct to 94.2 pct reduction in area by swaging on the recrystallization behavior and grain size distribution in Ti (0.2 pct O_eq) was investigated. In keeping with commonly observed behavior, increasing amounts of cold work lead to an increase in hardness prior to annealing and a decrease in the subsequent recrystallization temperature and grain size. Also, there occurred for the recrystallized grains a decrease in the standard deviation of the grain volume distribution In Σ_v deduced from the one-dimensional linear intercept measurements. The decrease in In Σ_v with cold work in swaged Ti is in good accord with that reported by Rhines and Patterson following uniaxial deformation of Al. Considering the results for both Al and Ti, it appears that the largest decrease in In Σ_v occurs for true strains up to R ~0.5, the change with larger strains being more gradual. The reason for the decrease in In Σ_v with increased cold work is not completely clear. The increased rate of grain growth with reduction in amount of cold work can be understood in terms of the larger number of three-edged grain faces which occur with the greater spread in the recrystallized grain volume distribution.