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

Patent metadata

Field	Value
Publication number	US-2016355916-A1
Application number	US-201415102965-A
Country	US
Kind code	A1
Filing date	Dec 11, 2014
Priority date	Dec 13, 2013
Publication date	Dec 8, 2016
Grant date	—

Abstract

The invention relates to a method for manufacturing an aluminium alloy product including the steps of: creating a bath of liquid metal in an aluminium-copper-lithium alloy, casting said alloy by vertical semi-continuous casting so as to obtain a plate with thickness T and width W such that, during solidification, the hydrogen content of said liquid metal bath (1) is lower than 0.4 ml/100 g, the oxygen content above the liquid surface ( 14, 15 ) is less than 0.5% by volume.

First claim

1 . 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.

2 . The method according to claim 1 wherein the oxygen content of the atmosphere in contact with the liquid metal bath in a smelter during degassing, filtration is less than 0 5% by volume and optionally wherein the oxygen content of the atmosphere in contact with the liquid metal bath is less than 0 5% by volume for the entire casting facility.

3 . The method according to claim 1 wherein a lid covers the liquid surface during solidification, said lid optionally comprising seals to ensure a leak tight seal with a casting table and wherein an inert gas is introduced into a chamber defined between the lid and the casting table and wherein suction is maintained in a casting pit by means of a pump, optionally so that the pressure within a containment is less than the pressure in the chamber.

4 . The method according to claim 1 in which a molten salt containing lithium is not used throughout the entire casting facility.

5 . The method according to claim 1 in which said distributor device is such that the first fabric has a height hl as measured from the upper face on the circumference of a wall such that h 1 ≧0.3 h and optionally h 1 ≧0.5 h, where h is the total height of a wall of the distributor device.

6 . The method according to claim 1 in which the height of a wall immersed in liquid metal of the distributor device covered by the first fabric is selected from the group consisting of at least 20%, 40%, and 60% of the total height of the immersed wall.

7 . The method according to claim 1 in which a surface portion covered by the first fabric is from 30 and 90%, and optionally from 50 and 80% for longitudinal portions and, and/or from 30 and 70% and optionally from 40 and 60% for lateral portions, and/or from 30 and 100% and optionally from 50 and 80% for a bottom.

8 . The method according to claim 1 wherein after (a) and (b),
(c) Homogenizing said slab before or after optionally machining to obtain a shape that can be hot-worked,
(d) said homogenized shape is then hot-worked and optionally cold-worked to obtain a wrought product.
(e) said wrought product is solution heat-treated and quenched,
(f) optionally said wrought product that has undergone solution heat treatment is stress-relieved by plastic deformation with a deformation of at least 1%,
(g) said solution heat-treated and optionally stress relieved product is subjected to aging.

9 . The method according to claim 1 wherein said hot working and/or cold-working is performed by extrusion, rolling and/or forging.

10 . The method according to any of claim 1 wherein said wrought product has a thickness of at least 80 mm

11 . The method according to claim 8 in which the deformation ratio during (d) is lower than 85%, and optionally lower than 80%.

12 . The method according to claim 1 in which the alloy comprises, as a percentage by weight, Cu: 3.0-3.9; Li: 0.7-1.3; Mg: 0.1 to 1.0, at least one element selected from Zr, Mn and Ti, the amount of said element, if selected, is from 0.06 to 0.15 wt % for Zr, 0.05 to 0.8 wt % for Mn and 0.01 to 0.15% by weight for Ti; Ag: 0-0.7; Zn≦0.25; Si≦0.08; Fe≦0.10; others ≦0.05 each and ≦0.15 in total.

13 . Distributor used for semi-continuous casting of aluminum alloy slabs made of fabric comprising essentially carbon, having a lower face, an upper face defining an 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 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.

14 . Distributor according to claim 13 wherein the first fabric has a height h 1 as measured from the upper face on the circumference of the wall such that h 1 ≧0.3 h and optionally h 1 ≧0.5 h, where h is the total height of a wall of the distributor device.

15 . Distributor according to claim 13 wherein the section of the wall changes linearly as a function of height h, optionally so that a surface of a lower face of the distributor is higher or lower by at most 10% than a surface of an upper face of the distributor.

16 . Distributor according to claim 13 wherein a surface portion covered by the first fabric is between 30 and 90%, and preferably optionally between 50 and 80% for longitudinal portions, and/or between 30 and 70% and preferably optionally between 40 and 60% for lateral portions, and/or between 30 and 100% and preferably between 50 and 80% for a bottom.

17 . Distributor according to claim 13 wherein length L 1 of the first fabric located in a bottom is greater than length L 2 of the first fabric in a portion of longitudinal walls in contact with the bottom.

18 . Distributor according to claim 13 wherein the first fabric and the second fabric are obtained by weaving a graphite wire.

19 . Distributor according to claim 18 wherein the wire is coated with a layer to facilitate sliding.

20 . Distributor according to any of claim 13 wherein the first fabric is substantially sealing, optionally having a mesh size of less than 0.5 mm, optionally less than 0.2 mm and/or the second fabric is non-sealing and allows molten metal to pass through, optionally having a mesh size of between 1 and 5 mm, optionally 2 to

Assignees

• Constellium Issoire

Inventors

• Danielou Armelle
• Blais Soizic
• Jarry Philippe
• Ribaud Olivier
• Valentin Bernard

Classifications

• B22D11/059

  Mould materials or platings · CPC title

• B22D11/041

  for vertical casting (B22D11/043, B22D11/049 - B22D11/059 take precedence) · CPC title

• B22D11/103

  Distributing the molten metal, e.g. using runners, floats, distributors · CPC title

• C22C21/18

  with zinc · CPC title

• C22C21/12

  with copper as the next major constituent · CPC title