An aluminum alloy brazing sheet used for brazing of an aluminum material in an inert gas atmosphere or in vacuum is formed of a two-layer material in which a brazing material and a core material are stacked. The core material is formed of an aluminum alloy and has a grain size of 20 to 300 μm, and the aluminum alloy contains Mn of 0.50 to 2.00 mass %, Mg of 0.40 to 2.00 mass %. Si of 1.50 mass % or less, Fe of 1.00 mass % or less, and Ti of 0.10 to 0.30 mass %, with the balance being aluminum and inevitable impurities. The brazing material is formed of an aluminum alloy containing Si of 4.00 to 13.00 mass % with the balance being aluminum and inevitable impurities. In a drop-type fluidity test, a ratio α (α=K.sub.a/K.sub.b) of a fluid coefficient K.sub.a is 0.50 or more.

An aluminum alloy brazing sheet used for brazing of an aluminum material in an inert gas atmosphere or in vacuum is formed of a two-layer material in which a brazing material and a core material are stacked in this order. The core material is formed of an aluminum alloy and has a grain size of 20 to 300 μm, and the aluminum alloy contains Mn of 0.50 to 2.00 mass %, Mg of 0.40 to 2.00 mass %, Si of 1.50 mass % or less, and Fe of 1.00 mass % or less, with the balance being aluminum and inevitable impurities. The brazing material is formed of an aluminum alloy containing Si of 4.00 to 13.00 mass % with the balance being aluminum and inevitable impurities, and, in a drop-type fluidity test, a ratio α (α=K.sub.a/K.sub.b) of a fluid coefficient K.sub.a is 0.50 or more.

In a brazing sheet manufacturing method, a cladding slab is prepared by overlaying at least a core-material slab composed of an aluminum material and a filler-material slab composed of an Al—Si series alloy, in which a metal element that oxidizes more readily than Al is included in at least one of the slabs. A clad sheet is prepared by hot rolling this cladding slab, which then has at least a core material layer composed of the core-material slab and a filler material layer composed of the filler-material slab and disposed on at least one side of the core material. Then, a surface of the clad sheet is etched using a liquid etchant that contains an acid. Subsequently, the clad sheet is cold rolled to a desired thickness. In flux-free brazing, such a brazing sheet is capable of curtailing degradation in brazeability caused by fluctuations in dew point and oxygen concentration.

An aluminum alloy brazing sheet including a core material and a brazing material provided on at least one surface of the core material. The brazing material includes 5.0-9.0 mass % Si, 0.10-0.90 mass % Mg, and 0.05-0.60 mass % Bi, and further includes at least one of 0.80 mass % or less Mn and 0.60 mass % or less Ti, with the remainder being Al and inevitable impurities.

An aluminum alloy brazing sheet has a 3XXX, 1XXX or 6XXX core, an interliner and a 4XXX brazing layer without added Mg. The interliner has Bi and Mg, the magnesium migrating to the surface of the brazing sheet during brazing and reducing the aluminum oxide to facilitate brazing without flux in a controlled inert atmosphere with reduced oxygen.

Brazing strip or sheet comprising: a core layer made of aluminum alloy; a brazing layer made of aluminum alloy, clad on at least one face of the core layer; optionally an intermediate layer made of aluminum alloy, clad on at least one face either between the core layer and the brazing layer or the core layer without any other layer on top; characterized in that the brazing layer alloy comprises, in mass percentages:
from 7 to 13% Si, at most 0.8% Fe, at most 0.45% Cu, at most 0.20% Mn, at most 0.15% Mg, at most 0.20% Zn, at most 0.20% Ti, at most 0.04% Bi, from 0.01 to 0.10% Y, from 0.01 to 0.10% Sn, remainder aluminum and impurities.

An aluminum brazing sheet having a multi-layer structure of two layers or more, an aluminum alloy brazing material being located on an outermost surface by being cladded on one surface or both surfaces of a core material, and the aluminum brazing sheet being applied to brazing in which the aluminum brazing sheet is bonded to a member to be brazed made of aluminum or an aluminum alloy without using a flux in a non-oxidizing atmosphere without decompression. The brazing material is made of an Al—Si—Mg—Sn brazing material containing, by mass %, 0.01% to 2.0% of Mg, 1.5% to 14% of Si, and 0.005% to 1.5% of Sn, and in observation in a surface direction before brazing, there are more than 10 Mg—Sn compounds with a circle equivalent diameter of 0.01 μm or more and less than 5.0 μm in the Al—Si—Mg—Sn brazing material per 10000 μm.sup.2 field of view.

A laminate sheet including a weldable margin is formed by laminating metal sheets having a core layer disposed therebetween. The core layer is formed of a core material which includes one or more of a viscoelastic, adhesive and acoustic material. The core layer is selectively distributed such that the laminate sheet includes an adhered region providing a laminate structure, and a non-adhered region including a weldable margin. The non-adhered region is adjacent an edge of the core layer and is characterized by a gap between the first and second metal sheets and by an absence of the core layer in the gap. The non-adhered region defines a weldable margin adjacent a core edge configured such that a weld is formable in the weldable margin without heat affecting the core layer. The laminate sheet can be joined by fasteners installed in the non-adhered region.

A brazing sheet may be used for brazing under an atmosphere of an inert gas without flux. The brazing sheet may include at least three layers. The at least three layers may include a core material, a brazing material layer, and an intermediate layer. The at least three layers may be cladded by an outermost layer of the brazing material layer. The intermediate layer may be disposed on a face of the core material. The core material may be composed of a first aluminum alloy including at least one of (i) 0.20 weight % to 1.0 weight % of Cu, (ii) 0.8 weight % to 1.8 weight % of Mn, and (iii) 0.25 weight % to 1.5 weight % of Mg. The intermediate layer may be composed of a second aluminum alloy including 0.20 weight % or less of each of Si and Fe and 0.10 weight % or less of each of Cu, Mn, and Cr.

A brazing sheet (1) includes a core material (11) composed of an Al alloy containing 0.40-2.50 mass % Mg; and a filler material (12) composed of an Al alloy containing Mg, 6.0-13.0 mass % Si, and 0.010-0.050 mass % Bi. The filler material is layered on a side of the core material and is exposed at an outermost surface (121). The Mg concentration in the filler material continuously decreases in a direction from a boundary (122) with the core material toward the outermost surface. The Mg concentration (c.sub.1/8) is 0.080 mass % or less at a depth (position P.sub.1/8) from the outermost surface that is ⅛ of the thickness t.sub.f of the filler material (12). The Mg concentration (c.sub.7/8) is 15-45% of the amount of Mg in the core material at a depth (position P.sub.7/8) from the outermost surface that is ⅞ of the thickness t.sub.f of the filler material.