Abstract
The relationship between the mechanism of high temperature deformation and the evolution behavior of microstructure and the texture during deformation, which has been found in various solid solution alloys, is clarified. It is shown that the preferential dynamic grain growth (PDGG) mechanism proposed by the authors can explain the behavior of microstructure change as well as texture change of all studied alloys without contradiction. The essential aspect of the PDGG mechanism is the preferential growth of crystal grains with the orientation stable for deformation and with low Taylor factor in the given deformation mode. It is concluded that the Taylor factor corresponds to dislocation density and stored energy during the high temperature deformation of solid solution alloys when viscous glide of dislocations is the rate controlling process. The possibility of the occurrence of the PDGG mechanism in materials other than solid solution alloys is also discussed.
Uniaxial compression deformation constructs 〈001〉 (compression axis) texture instead of usual deformation texture with the main component 〈011〉, when preferential dynamic grain growth (PDGG) mechanism operates in high temperature deformation. The contours in the figure show the development of (001) texture by the PDGG mechanism for the commercial Al–Mg alloy AA5082 after the deformation up −1.0 in true strain. Pole densities 2, 4, 6, 8, 10 and 12 times of the random level are given as a function of temperature and strain rate. ①, ② and ③ give the deformation conditions where the PDGG mechanism works. Comparison of the deformation conditions ①, ② and ③ with the high temperature deformation mechanism map suggests that PDGG mechanism operates when friction stress such as the stress for solute atmosphere dragging exists for the movement of dislocations.
Fullsize Image
