Yoshikazu Hosoi, Eiichi Sawato and Mamoru Yukawa
In this experiment the Vickers hardness was measured on the Al rods extruded with the 88.6% reduction circle die at 400° and 500° and its hardness changes in annealing so that we might investigate how extension and compression of the rod extruded at high temperature have effect upon its annealing process. Results obtained are as follows : (1) When worked below the plastic deformation range, the extruded Al rod becomes soft and when worked more it is hardened as cold worked Al. This is remarkably observed in the case of the rod extruded at 500°. (2) The rod softened by slight working is hardened in lower temperature annealing, while the rod hardened by more working is soften just like rods simply extruded. (3) The softening point,by recrystallization may-be, is no effected by such slight working as makes the rods soften. When worked more it shifts to considerably lower temperature and it is remarkable in the rod extruded at 400°. The details mentioned above are also discussed referring to X-ray photographs (by CuKα line).
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