ALLUMINUM ALLOY SHEET SUPERIOR IN PAINT BAKING HARDENABILITY AND INVULNERABLE TO ROOM TEMPERATURE AGING, AND METHOD FOR PRODUCTION THEREOF

摘要

PURPOSE: An alluminum alloy sheet superior in paint baking hardenability and invulnerable to room temperature aging, and a manufacturing method thereof are provided to improve bending workability such as hemming by suppressing the formation of Si rich cluster and room temperature aging. CONSTITUTION: An alluminum alloy sheet comprises Mg(0.4~1.0 mass%), Si(0.4~1.5%), Mn(0.01~0.5 mass%), and Cu(0.001~1.0 mass%). The cluster which is aggregate of an atom is observed as dark color contrast. The average water density of the cluster in which the circle equivalent diameter of the dark color contrast is the range of 1~5nm is 4000~30000/2micron.