PRODUCTION OF ALUMINUM ALLOY SHEET EXCELLENT IN FORMABILITY AND HARDENABILITY IN COATING/BAKING AND HAVING DELAYED AGING CHARACTERISTIC AT ORDINARY TEMPERATURE

摘要

PURPOSE: To obtain an Al alloy sheet having excellent press formability, delayed aging characteristic at ordinary temp., and hardenability in coating/baking by subjecting an ingot of Al alloy with specific composition to homogenizing treatment and to hot rolling and cold rolling and further subjecting the resultant sheet to heating and holding under specific temp. conditions, to cooling, and then to heat treatment. ;CONSTITUTION: An ingot of an Al alloy, which has a composition containing, by weight, 1.5-3.5% Mg, 0.3-1.0% Cu (where Mg/Cu is regulated to 2-7), 0.05-0.35% Si, 0.03-0.50% Fe, 0.005-0.15% Ti, and 0.0002-0.05% B or further containing one or ≥2 kinds among specific small amounts of Mn, Cr, Zr, V, and Zn, is subjected to single state or multistage homogenizing treatment at 400-500°C. This Al alloy ingot is hot-rolled and cold- rolled into an Al alloy sheet of desired sheet thickness, which is heated to 550-580°C at ≥3°C/sec temp. rise rate and held for 0-60sec. Subsequently, this sheet is cooled at ≥2°C/sec cooling rate, subjected, after standing at room temp. or directly, to heat treatment at 45-110°C for 2-48hr, and then held at 180-300°C for 3-60sec.;COPYRIGHT: (C)1995,JPO