MULTI-LAYER ALUMINUM ALLOY BRAZING SHEET

摘要

A composite brazing material is described, composed of a layer (usually an ingot) of high manganese content aluminum alloy (3000 series alloy; the "core") and a layer of high silicon content aluminum alloy (4000 series alloy; the "cladding") with a layer of aluminum alloy having the following composition. Silicon 6.8 - 8.2 wgt. %; iron up to 0.8 wgt. %; copper up to 0.25 wgt. %; manganese up to 0.10 wgt. %; zinc up to 0.20 wgt. %; other elements up to 0.15 wgt. %; and aluminum balance disposed between the cladding and core layers and in contact with both. Subsequent hot rolling of the multi-layer composite produces a good bond between the core and the cladding through the intermediate layer. The resulting brazing material has the external properties of a simple two-layer composite of core and cladding without the intermediate layer. The three layer composite of the present invention, however, has a much stronger interlayer bond and is not subject to the serious delamination or bond failures of the prior art two-layer materials. Additional composite layers can also be used, with a layer of the intermediate alloy as described herein placed between each successive pair of the 3000 and 4000 series alloy layers. One typical configuration is composed of a 3003 core, clad each side with 4104 alloy sheets and with a 4343 intermediate alloy sheet on either side of the core between the core and each cladding sheet.