Shiro Terai1 and Yoshio Baba1
1Research Laboratory of the Sumitomo Light Metal Industry Ltd., Nagoya
As a result of studying the effects of the purity of aluminium and the heat-treatment on the ``Work Softening'' phenomenon of aluminium, it was found that this phenomenon was observed in the special state of the commercially pure aluminium.
For example, 99.2% aluminium sheet annealed at 240°C after cold rolling, increased the elongation from 16 to 25% and decreased the proof stress from 12.0 to 10.6 kg/mm2 and the tensile strength from 12.5 to 11.8 kg/mm2 with reduction of 1% by cold rolling, after the annealing.
This ``Work Softening'' phenomenon was observed in the half hard sheet of 99.2% and 99.8% aluminium annealed at the final temperature of about 240°C when cold rolled with reduction of 1 to 5%, if the ingot had been preheated at 500°C for 24 hrs. It was also observed that this phenomenon had no connection with the intermediate annealing and the anisotropy of the sheets.
``Work Softening'' phenomenon was not observed in 99.99% aluminium and the commercially pure aluminium obtained from the ingot not preheated.
(Received 1962/5/31)
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