Honda Giken Kogyo Kabushiki Kaisha

Sumitomo Light Metal Industries, Ltd.

Hiden Yoshida

Noboru Hayashi

Kunihiro Yasunaga

Hidetoshi Uchida

Hideo Itoh

The invention provides an aluminum alloy sheet that has excellent formability, high coat-baking hardenability, excellent corrosion resistance, and is particularly suitable for external automobile body plates. The aluminum alloy sheet comprises: 0.9 to 1.3 wt. % of Si, 0.4 to 0.6 wt. % of Mg, 0.05 to 0.15 wt. % of Mn, 0.01 to 0.1 wt. % of Ti, with the remainder comprising Al and inevitable impurities, while limiting Fe as an impurity to 0.2 wt. % or less and Cu as an impurity to 0.1 wt. % or less. The aluminum homogenizing an aluminum ingot with the above-described composition; cooling the homogenized ingot to a temperature of 450.degree. C. or below to begin hot-rolling; finishing hot-rolling in a temperature range from 250 to 350.degree. C.; applying intermediate annealing to the hot-rolled plate; conducting cold-rolling at a draft of 70% or more; applying a solid solution treatment followed by quenching the alloy sheet and holding it at 530.degree. C. or above for 60 sec. or less; forming a chromate film onto the quenched alloy sheet; forming a film of a lubricant containing a water-dispersible polyurethane resin and a natural wax onto the chromate film; then applying a heat treatment to the coated alloy sheet in a temperature range of from 200 to 240.degree. C. for 60 sec. or less.

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Aichi, Japan

Hiden Yoshida