Method for manufacturing products made of aluminium-copper-lithium alloy with improved fatigue properties, and distributor for this method

Method of manufacturing an aluminum alloy product comprising

• (a) Preparing a bath of molten alloy metal 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 by vertical semi-continuous 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,
• a distributor device used for casting is made of fabric comprising essentially carbon;
• said distributor device comprises a lower face, an upper face defining the opening through which the molten metal is introduced and a wall of substantially rectangular section, 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 from at least two fabrics, a first substantially sealing and semi-rigid fabric ensuring that the distributor device keeps shape during casting, and a second non-sealing fabric allowing the passage and filtration of liquid, said first and second fabrics being bonded to each other without overlap or with overlap and no gap separating them, said first fabric continuously covering at least 30% of the surface of wall portions and being positioned so that a liquid surface is in contact therewith over an entire section.