Aluminium - copper - lithium alloy products with improved fatigue properties

A method of manufacturing an aluminium alloy plate having a thickness of at least about 80 mm comprising steps in which

• (a) a bath of molten alloy metal is prepared comprising, as a percentage by weight, Cu:
• 2.0-6.0;
• Li:
• 0.5-2.0;
• Mg:
• 0-1.0;
• Ag:
• 0-0.7;
• Zn 0-1.0;
• and at least one element selected from Zr, Mn, Cr, Sc, Hf and Ti, the amount of said element, if selected, being 0.05 to 0.20 wt % for Zr, 0.05 to 0.8% wt % t for Mn, 0.05 to 0.3 wt % for Cr and for Sc, 0.05 to 0.5 wt % Hf and 0.01 to 0.15% wt % for Ti, Si≦0.1;
• Fe≦0.1;
• others ≦0.05 each and ≦0.15 in total,
• (b) said alloy is cast t by semi-continuous vertical casting to obtain a slab of thickness T and width W so that upon solidification,
• the hydrogen content of said molten metal bath is less than about 0.4 ml/100 g,
• the oxygen content measured above the liquid surface is less than about 0.5% by volume,
• wherein said method utilizes a distributor device for casting, and wherein said distributor device is made of fabric comprising carbon, a lower face, an upper face defining the opening through which the molten metal is introduced, and a wall, the wall comprising two longitudinal portions parallel with width W and two transverse portions parallel with thickness T, said transverse and longitudinal portions being formed of at least two materials, a first substantially sealing material and semi-rigid material for maintaining the shape of the distributor device during casting and a second non-sealing material allowing the passage and filtration of liquid, said first and second materials being bonded to each other without overlap or with overlap and no gap separating them, said first material continuously covering at least about 30% of the surface of said wall portions and being positioned so that the liquid surface is in contact therewith,
• (c) said slab is homogenized before or after optionally machining it to get a rolling ingot that can be hot-worked,
• (d) said rolling ingot, homogenized in this way, is hot rolled and optionally cold rolled to obtain a plate having a thickness of at least about 80 mm,
• (e) said plate undergoes solution heat treatment and quenching,
• (f) optionally said plate that has undergone solution heat treatment is stress-relieved by plastic deformation with a deformation of at least 1%, and
• (g) said solution heat-treated and optionally stress-relieved plate is subjected to aging.