METHOD FOR MANUFACTURING A CLAD SHEET PRODUCT

Abstract

The invention concerns a method for the manufacturing of a clad sheet product comprising a core layer (6) and at least one cladding layer, the method comprising rolling an assembly of a core layer and at least one cladding layer and reducing the thickness to a desired gauge, the core layer being made of an aluminium alloy, the at least one cladding layer comprising a centre section (2) and at least two edge sections (4, 5) positioned at opposite sides of the centre section (2) along the edges of the at least one cladding layer, the centre section being made of a material being an aluminium alloy or a composite material comprising a matrix of aluminium or an aluminium alloy, the edge sections along (4, 5) the edges being made of a material different from the material of the centre section, wherein the edge sections (4, 5) are cut off during or after the rolling. The invention further concerns a cladding plate useful in the method.

Claims

1. A method for the manufacturing of a clad sheet product comprising a core layer and at least one cladding layer, the method comprising rolling an assembly of a core layer and at least one cladding layer and reducing the thickness to a desired gauge, the core layer being made of an aluminium alloy, the at least one cladding layer comprising a centre section and at least two edge sections positioned at opposite sides of the centre section along the edges of the at least one cladding layer, the centre section being made of a material being an aluminium alloy or a composite material comprising a matrix of aluminium or an aluminium alloy, the edge sections along the edges being made of a material different from the material of the centre section, wherein the edge sections are cut off during or after the rolling.

2. Method as claimed in claim 1, wherein the at least one cladding layer comprises edge sections that are side sections extending along the edges in the rolling direction.

3. Method as claimed in any one of the claim 1 or 2, wherein the at least one cladding layer comprises edge sections that are head and tail sections extending along the edges cross the rolling direction.

4. Method as claimed in any one of the claims 1-3, wherein the at least one cladding layer comprises both side sections extending along the edges in the rolling direction and head and tail sections extending along the edges cross the rolling direction.

5. Method as claimed in any one of the claims 1-4 comprising attaching a cladding plate forming at least one cladding layer to a core slab forming the core layer, said cladding plate comprising both the centre section and the edge sections of at least one cladding layer.

6. Method as claimed in any one of the claims 1-5, wherein the material of the edge sections is aluminium or an aluminium alloy.

7. Cladding plate useful in the manufacturing of a clad sheet product according to the method of any one of the claims 1-6, said cladding plate comprising at least one cladding layer comprising a centre section and at least two edge sections at opposite sides of the centre section along the edges of the cladding plate, the centre section being made of a material being an aluminium alloy or a composite material comprising a matrix of aluminium or an aluminium alloy, the edge sections along the edges being made of a material different from the material of the centre section.

8. Cladding plate as claimed in claim 7, wherein the at least one cladding layer comprises edge sections that are side sections along the edges in the intended rolling direction.

9. Cladding plate as claimed in any one of the claims 7-8, wherein the at least one cladding layer comprises edge sections that are head and tail sections extending along the edges cross the intended rolling direction.

10. Cladding plate as claimed in any one of the claims 8-9, wherein each side section along the edges in the intended rolling direction constitute from 1 to 20% of the total width of the cladding layer.

11. Cladding plate as claimed in any one of the claims 9-10, wherein each head and tail section extending along the edges cross the rolling direction constitute from 3 to 20% of the total length of the cladding layer.

12. Cladding plate as claimed in any one of the claims 7-11 comprising only one cladding layer.

13. Cladding plate as claimed in any one of the claims 7-11, comprising more than one cladding layer, at least one of them being provided with edge sections of a material different from the material of the centre section.

14. Cladding plate as claimed in any one of the claims 7-13, wherein the material of the centre section is made of a composite material comprising a matrix of aluminium or an aluminium alloy and a further material.

15. Cladding plate as claimed in claim 14, wherein the composite material is a matrix of aluminium or an aluminium alloy containing flux particles.

16. Cladding plate as claimed in any one of the claims 7-15, wherein the material of the edge sections is aluminium or an aluminium alloy.

Description

[0033] FIGS. 1-6 schematically show various embodiments of the invention.

[0034] FIG. 1 shows an assembly before rolling that comprises a core slab 6 and a single cladding layer. The cladding layer is attached to the core slab 6 and includes a centre section 2, side sections 4 along the edges in the rolling direction and head and tail sections 5 along the edges cross the rolling direction. The side sections 4 extend over the entire length of the assembly while the head and tail sections 5 only extend over the width of the centre section 2. The edge sections, i.e. the side sections 4 and the head and tail sections 5, can be made of the same or of different materials as long as it is different from the material of the centre section 2. The centre section 2 and the edge sections 4, 5, is preferably an integral cladding plate but may alternatively be separate pieces that have been attached to the core slab 6. At rolling, the gauge will be reduced and the length of the assembly will correspondingly be extended to obtain a long strip. The width of the side sections 4 along the rolling direction will remain essentially the same (although minor widening usually occurs), while the head and tail sections 5 will be substantially extended. At one or several stages during or after the rolling the edge sections 4, 5 are cut off and removed as scrap that subsequently can be remelted and recirculated to the production. The remaining part is normally slit into strips of a width suitable for the intended use. The embodiment shown is applicable for any kind of cladding layers, for example when the centre section 2 is made of a composite material of a matrix of a filler alloy as earlier described comprising flux particles. Although FIG. 1 only shows a cladding layer at one side of the core slab 6, it is to be understood that the same or similar kind of cladding layer may be applied at both sides of the core slab 6.

[0035] FIG. 2 shows an embodiment similar to the one of FIG. 1, with the exception that the head and tail sections 5 extend over the entire width of the assembly while the side sections 4 only extend over the length of the centre section 2. In all other aspects the embodiment of FIG. 2 is identical to the one of FIG. 1.

[0036] FIG. 3 shows an embodiment similar to the one in FIG. 1 but with cladding layers on both sides of the core slab. Further, each the cladding layer comprise a centre section 2 and side sections 4 extending along the edges in the rolling direction, but no separate head and tail sections, of a material different from the material of the centre section 2. In all other aspects the embodiment of FIG. 3 is identical to the one of FIG. 1.

[0037] FIG. 4 shows a cross section of a cladding plate according to an embodiment with three cladding layers. Only the cladding layer in the middle is provided with a centre section 2 and side sections 4 along the edges in the intended rolling direction of a material different from the centre section 2, while the two cladding layers 1, 3 arranged on each side thereof do not have separate centre and edge sections of different materials. The cladding layer in the middle may or may not have separate head and tail sections. The embodiment shown is, for example, applicable when the centre section 2 of the cladding layer in the middle is a composite material of a matrix of aluminium or an aluminium alloy (filler alloy or any other kind of aluminium alloy) comprising flux particles, while the other cladding layers 1, 3 are of a filler alloy. The filler alloy of the different layers may be identical or different filler alloys. The thickest cladding layer 3 is intended to face the core layer (not shown). A cladding plate as shown can be applied at only one side or at both side of a core slab (not shown).

[0038] FIG. 5 shows a cross section of a cladding plate with only two layers, one of which being provided with a centre section 2 and side sections 4 along the edges in the intended rolling direction of a material different from the centre section 2, while the other layer 3 does not have any separate edge sections. The embodiment shown is, for example, applicable when the centre section 2 is a composite material of a matrix of aluminium or an aluminium alloy (filler alloy or any other kind of aluminium alloy) comprising flux particles, while the other cladding layer 3 is of a filler alloy. A cladding plate as shown can be applied at only one side or at both side of a core slab (not shown). It can also be applied with any of the cladding layers facing the core slab.

[0039] FIG. 6 shows a cross section of an assembly before rolling that comprises of a core slab 6, an outer cladding layer and an intermediate cladding layer 7. The outer cladding layer includes a centre section 2 and side sections 4 along the edges in the rolling direction. The embodiment shown is applicable for any kind of cladding layers. For example, the centre section 2 may be made of a filler alloy or of a composite material of a matrix of a filler alloy comprising flux particles. The intermediate layer 7 may be of any suitable aluminium alloy, for example for inhibiting migration of Si from the filler alloy in the outer cladding layer into the core 6 during brazing or for serving as a sacrificial layer. The outer and intermediate cladding layers may be attached to the core slab as separate cladding plates or as a pre-prepared two layered cladding plate. Although FIG. 5 only shows cladding layers at one side of the core slab 6, it is to be understood that the same or similar kind of cladding layer may be applied at both sides of the core slab 6.

[0040] The invention is further described in connection with the following Examples, which, however, is not intended to limit the scope of the invention.

EXAMPLE 1

[0041] Cladding plates comprising of a centre section and two parallel side sections extending along the intended rolling direction were prepared by attaching two 3.9 m70 mm25 mm AA3003 bars for the side sections to a 3.9 m0.9 m25 mm plate for the centre by friction stir welding. The plate for the centre section was made of flux composite material of an aluminium alloy matrix containing approximately 4-5 wt % flux particles prepared by spray forming a billet according to WO2008/110808 followed by extrusion and friction stir welding. The aluminium alloy matrix in the flux composite material was a filler alloy AA4045 (Al with 10 wt % Si) and the flux was AlKF.sub.4.

[0042] The cladding plates were attached by welding on both sides of a 4.1 m1.05 m355 mm DC cast core slab to form an assembly as shown in FIG. 3. The core slab was made of an aluminium alloy consisting of, in wt %, 0.5 Si, 0.5 Fe, 0.25-0.50 Cu, 1.0-2.0 Mn, 0.03 Mg, 0.10 Zn, 0.08-0.25 Ti, other elements 0.05 each and 0.15 in total, balance Al. The contact surfaces were milled.

[0043] The assembly was hot rolled at about 450 C. to a gauge of 3.7 mm and then cold rolled to obtain a clad strip having a final gauge of 0.485 mm. During the cold rolling process totally 40 mm at each side along the rolling direction was cut off, thus no material from the centre section was included in the scrap obtained. Finally, the coil was slit into several rings and in total only 33 mm from each side of the composite material was scrapped. Inspection of the final strip obtained in the rolling revealed that the cladding thickness was essentially uniform across the entire width cross the rolling direction.

EXAMPLE 2

[0044] Cladding plates were prepared as in Example 1 with the exceptions that the bars for the side sections were made of AA6063 and had the dimensions 3.9 m120 mm25 mm, and that the centre section had the dimension 3.9 m1.191 m25 mm.

[0045] The cladding plates were welded on both sides of a core slab as in Example 1 with the exception that the size of the core slab was to 4.1 m1.44 m355 mm.

[0046] The materials of the core slab and the centre section of the cladding plates were the same as in Example 1.

[0047] The assembly was hot rolled at about 465 C. to a gauge of 3.7 mm and then cold rolled to obtain a clad strip having a final gauge of 0.485 mm. During the cold rolling process totally 20 mm at each side along the rolling direction was cut off, thus no material from the centre section was included in the scrap obtained. Finally, the coil was slit into several rings utilising 1112 mm, thus in total only 39.5 mm from each side of the composite material was scrapped.

[0048] Inspection of the final strip obtained in in the rolling revealed that the cladding thickness was essentially uniform across the entire width cross the rolling direction.