Patent ID: 6551424
Filing Date: 2003-04-22
Classification: C22C,C22F

Abstract:
A method for manufacturing an aluminium-magnesium-lithium product, comprising the steps of subsequently:(a) providing an aluminium alloy consisting essentially of (in weight %): Mg 3.0-6.0; Li 0.4-3.0; Zn up to 2.0; Mn up to 1.0; Ag up to 0.5; Fe up to 0.3; Si up to 0.3; Cu up to 0.3; and 0.02-0.5 selected from at least one member from the group consisting of Sc 0.010-0.40; Hf 0.010-0.25; Ti 0.010-0.25; V 0.010-0.30; Nd 0.010-0.20; Zr 0.020-0.25; Cr 0.020-0.25; Y 0.005-0.20; and Be 0.002-0.10; balance consisting essentially of aluminium and incidental elements and impurities; (b) casting the aluminium alloy into an ingot; (c) preheating the ingot; (d) hot rolling the preheated ingot to a hot worked intermediate product; (e) cold rolling the hot worked intermediate product to a rolled product in both the length and in the width direction with a total cold rolling reduction of at least 15%; (f) solution heat treating the cold rolled product in the temperature range of 465 to 565Â° C. for a soaking time in the range of 0.15 to 8 hours; (g) cooling the solution heat treated product from the solution heat treatment temperature below 150Â° C. with a cooling rate of at least 0.2Â° C./sec; and (h) ageing the cooled product to provide a sheet or thin plate product having a minimum yield strength of at least 260 MPa and a minimum tensile strength at least 400 MPa in at least the L- and LT-direction, a minimum yield strength of at least 230 MPa and a minimum tensile strength of at least 380 MPa in the 45Â° to the L-direction.