Abstract
As the mass of ingots of Al-Zr alloy becomes larger, especially in the case of a Zr rich alloy, the center region constitutes the equiaxed structure and the columnar structure appears in the part of ingot in contact with the mould where the metal is cooled rapidly.
The results are summerized as follows:
(1) The difference in characteristics of recrystallization between the chilled zone and the center were recognized in the case of ingots whose thickness exceed 30mm and in the alloy containing over 0.23wt% of Zr.
(2) The recrystallization temperature of columnar zone is generally high but that of equiaxed structure is not so high. Precipitates become finer and fewer in columnar zone than in the equiaxed zone. Electrical resistance of the drawn wire from the equiaxed zone is also much lower than that of from the columnar zone.
(3) The precipitation heat treatment after cold rolling is effective to level up recrystallization temperature of a Zr dilute alloy, but is not entirely effective to that of an equiaxed zone.
