The Influence of Silicon Content on Recrystallization of Twin-Roll Cast Aluminum Alloys for Heat Exchangers

Thin foils of aluminum alloys are commonly used in automotive industry for manufacturing heat exchangers. Use of twin-roll casting instead of direct-chill casting requires modifications in the manufacturing process and use of improved materials. In the present study, the evolution in microstructure and mechanical properties during isochronal annealing of two AW3003-based alloys differing in silicon content was monitored. The silicon influenced both the microhardness and precipitation kinetics during annealing, but not the recrystallization temperature. Precipitation of cubic $\alphs-Al_{15}(Mn,Fe)_3Si_2$ phase occurred in two steps in the material with higher Si content, while mainly precipitates of $Al_6(Mn,Fe)$ phase formed in the second material in a broad temperature interval, preferentially at grain boundaries.