2008 Volume 49 Issue 2 Pages 250-259
This investigation studies 3003 aluminum alloys for automobile heat exchangers. The effects of precipitation in homogenization treatments, recrystallization in extrusion and brazing on extrusion forming ability and final material properties are examined. At first, fine second phase particles were precipitated during the 460°C × 9 h homogenization treatment and coarse particles were precipitated by homogenization treatments with 600°C × 9 h. Second, when the precipitation were not plentiful and fine enough during extrusion, the amount of solution dominated the extrusion breakout pressure, and recrystallization was easier; on the contrary, the domination state was replaced by plentiful and fine precipitated particles, and recrystallization became more difficult. Additionally, the hardness after extrusion was lower in the complete recrystallization position, and higher in the incomplete recrystallization position. Finally, in brazing, the sample under the 460°C × 9 h condition (a) underwent full recrystallization from partial recrystallization with a reduction in strength; the local position of the edge of the sample under the 600°C × 9 h → 460°C × 3 h condition (c) exhibited a second recrystallization and a significant drop in hardness.
