To obtain an alloy plate that surface roughness in the bent part is prevented, and a balance of strength and ductility is excellent by subjecting an Al-Mn alloy to casting in such a manner that the content of Mn solid solution is made to be the specified one, executing homogenizing precipitating treatment in such a manner that the Mn solid solution content is made to be the specified one, and the quantity of intermetallic compds. of specified size is made to be the one below the specified quantity and thereafter executing cold rolling, heating and recrystallization annealing.
An Al-Mn alloy contg. 1 to 2.6% Mn, and in which, as to impurities, the content of Fe is controlled to <0.5%, and that of Si to <0.4% is cast in such a manner that the Mn solid solution content exceeds 60% of the amt. of Mn to be added, next, homogenizing precipitating treatment is executed in such a manner that the Mn solid solution content is controlled to <0.4%, and the number of intermetallic compds. in which the diameter equivalent to a circle exceeds 6 μm is controlled to <1 pieces/mm2, it is subjected to cold rolling at 88 to 99.8% rolling ratio, and recrystallization annealing is executed in such a manner that it is heated at 300 to 400°C at a temp. rising rate of ≥5°C/sec, is held for 0 to 180 sec and is cooled at a cooling rate of ≥10°C/sec to obtain an Al-Mn alloy rolling stock having a fine recrystallized structure of ≤7 μm average crystal grain size.
MURAMATSU TOSHIKI
SKY ALUMINIUM
SUMITOMO LIGHT METAL IND
NIPPON LIGHT METAL CO
FURUKAWA ELECTRIC CO LTD
MITSUBISHI ALUMINIUM
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