Relationship between room-temperature proof stress, dislocation density and subgrain size

Abstract

High-temperature deformation of A1-1 wt.% wg-1 wt. % Mn has been carried out in plane-strain compression at constant strain rate and temperature, and with abrupt changes in Zener-Hollomon parameter. Subgrain sizes and dislocation densities within subgrains have been measured and correlated with the roomtemperature proof strength. It is found that the proof strength depends primarily on the dislocation density within subgrains. The subgrain size has a lesser role which is interpreted in terms of the fact that dislocations within boundaries have a lower strengthening efficiency per dislocation. For constant hot-deformation conditions the dislocation density and subgrain size are uniquely related. The strength can then be correlated with subgrain size only, but terms in d⁻¹ and in d^−1/2 are both required.