A new process of producing airplane frames wasdesigned to reduce the costs. In this now process. 7475-Waluminium alloy sheets followed by reversion heat treatment(RHT) were used before roll formings instead of 7475-O ones. Inthis process, the hardness of the sheets after RAT should bebelow HV120, which was the limited hardness of roll forming.The most suitable condition of RHT, 453K~4Os wasrecommended in this study. But the hardness after RHT wasn'treduced to the as-quenched condition. Furthermore, the hardnessof the as-quenched specimen followed by RHT was raised toHV110 level. It was confirmed that copper addition reduces theprecipitating temperature of eta#' and eta# phase in the Al-Zn-Mgalloy. Then it was suggested that the dissolution of GP Zones andprecipitation of #eta# and #eta# phase occurred simultaneouslyin 7475-W aluminium alloy sheet at the reversion heat treatment of 453K-40s.
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