The influence of warm rolling parameters (temperature and reheating time between passes) on the superplastic response of Al-Mg alloys

Abstract

The effects of rolling temperature and reheating interval between consecutive rolling passes on the superplastic response of two Al-Mg alloys were investigated. The alloys were Al-8%Mg-0 .1%Zr and Al-10%Mg-0 .1%Zr (wt. pct.). The effects of varying the process parameters were observed on resultant superplastic ductility during testing at 300°C. The data support a model for microstructure evolution during processing by a mechanism of continuous recrystallization (CRX). The model for CRX assumes that dislocations recover to sub boundaries which are stabilized by precipitates, of size on the order of one micron, located at nodes of the substructure. Continued recovery results in formation of boundaries of moderate misorientation, in the absence of the migration of a high angle boundary. The dependence of CRX on reheating time and rolling temperature was investigated and a strong dependence of subsequent superplastic response on these two processing parameters was observed. The influence of grain size on resultant superplasticity was also noted, indicating that the extent of grain refinement is limited to the spacing of particles.