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 includes 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. The brazing material is formed of an aluminum alloy including Si of 4.00 to 13.00 mass % and one or two or more of Mn of 2.00 mass or less, Ti of 0.30 mass % or less, Zr of 0.30 mass % or less, and Cr of 0.30 mass % or less.

The disclosed technology relates generally to welding, and more particularly to consumable electrodes based on aluminum. In one aspect, a consumable welding electrode comprises a base metal composition comprising magnesium (Mg) and at least 70% by weight of aluminum (Al), and a smut-suppressing metal. A standard free energy change (ΔG°) of formation of a smut-suppressing oxide by oxidation of the smut-suppressing metal under equilibrium conditions at a temperature of 1600K or higher is more negative than a ΔG° of formation of MgO by oxidation of Mg, such that the smut-suppressing metal is configured to form the smut-suppressing oxide that is thermodynamically more favored over MgO on a surface of a weld metal formed from the consumable welding electrode. The smut-suppressing metal is present in an amount of 0.05-0.50% by weight of the consumable welding electrode.

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.

This invention relates to the field of welding high strength aluminum structures, and more particularly to the alloy filler metal composition, its resultant microstructure, and the physical and mechanical properties which are obtained in the weld bead during fusion welding. A composition for producing small diameter aluminum welding filler metal wires having a chemistry comprising Si varying from approximately 0.3 to 0.9 wt. %, Mn varying from approximately 0.05 to 1.2 wt. %, Mg varying from approximately 2.0 to 7.0 wt. %, Cr varying from approximately 0.05 to 0.30 wt. %, Zr varying from approximately 0.05 to 0.30 wt. %, Ti varying from approximately 0.003 to 0.20 wt. %, and B varying from approximately 0.0010 to 0.030 wt. %, and a remainder of aluminum and various trace elements.

An aluminum alloy for flux-free brazing provided for brazing performed via an Al-Si-based brazing material without a flux in a non-oxidizing atmosphere without depressurization, includes: by mass %, 0.01% to 2.0% of Mg; and 0.005% to 1.5% of Bi, wherein in the aluminum alloy, there are more than 10 Mg-Bi-based compounds having a diameter of 0.01 μm or more and less than 5.0 μm in terms of equivalent circle diameter per 10,000-μm.sup.2 visual field and there are less than 2 Mg-Bi-based compounds having a diameter of 5.0 μm or more per 10,000-μm.sup.2 visual field in a cross section parallel to a rolling direction, and in the aluminum alloy, there are less than 5 Bi particles having a diameter of 5.0 μm or more in terms of equivalent circle diameter per 10,000-μm.sup.2 visual field in the cross section parallel to the rolling direction.

An aluminum brazing sheet has a multilayer structure of two or more layers of at least a core material and a brazing material, wherein an Al—Si—Mg—Bi-based brazing material containing, by mass %, 0.01% to 2.0% of Mg, 1.5% to 14.0% of Si, and 0.005% to 1.5% of Bi is clad on one surface or both surfaces of the core material to be located at an outermost surface of the aluminum brazing sheet, in the Al—Si—Mg—Bi based brazing material, there are more than 10 Mg—Bi-based compounds having a diameter of 0.01 μm or more and less than 5.0 μm when observed in a surface layer plane direction and there are less than 2 Mg—Bi-based compounds having a diameter of 5.0 μm or more, and in the brazing material, there are less than 5 Bi particles having a diameter of 5.0 μm or more when observed in the surface layer plane direction.

A welding method for a connector and a connection tube of a heat exchanger are proposed. The method includes: forming a diffusion layer on a surface of the connector, a corrosion potential of the diffusion layer being less than a corrosion potential of the connector; inserting a connection tube into the connector; brazing the connection tube to the connector by a brazing filler metal, a corrosion potential of a weld metal formed after brazing of the brazing filler metal being higher than the corrosion potential of the connector and less than a corrosion potential of the connection tube.

An aluminum alloy brazing sheet used for brazing in an inert gas atmosphere without using a flux includes an intermediate material and a brazing material cladded onto at least one side surface of a core material in this order from the core material side. An oxide is formed on a surface of the aluminum alloy brazing sheet by brazing heating, the oxide including any one or two or more of Mg, Li, and Ca and having a volume change ratio of 0.990 or less to a surface oxide film formed before brazing heating, and an atomic molar ratio of Mg, Li, and Ca to Al in the oxide formed on the surface of the aluminum alloy brazing sheet before brazing heating is 0.5 or less. The present invention provides an aluminum alloy brazing sheet having excellent brazability in brazing in an inert gas atmosphere without using a flux, and a method for manufacturing the same.

A flux-free brazing aluminum alloy brazing sheet includes: a core material formed of aluminum alloy comprising Si of 0.50 to 0.90 mass %, Cu of 0.30 to 2.50 mass %, and Mn of 1.40 to 1.80 mass %, with a Mg content limited to 0.05 mass % or less, and with the balance being Al and inevitable impurities; an intermediate material being formed of aluminum alloy comprising Mg of 0.40 to 1.00 mass %, and Zn of 2.00 to 6.00 mass %, with the balance being Al and inevitable impurities; and a brazing material being formed of aluminum alloy comprising Si of 6.00 to 13.00 mass %, Mg of 0.05 to 0.40 mass %, and Bi of 0.010 to 0.050 mass %, with the balance being Al and inevitable impurities.

An aluminum alloy brazing sheet used for brazing in an inert gas atmosphere without using flux includes a core material of aluminum or aluminum alloy, and a brazing material of aluminum alloy including Si of 4.0 mass % to 13.0 mass % and cladding one side surface or both side surfaces of the core material. One or both of the core material and the brazing material includes any one or two or more types of X atoms (X is Mg, Li, Be, Ca, Ce, La, Y, and Zr). The aluminum alloy brazing sheet is a brazing sheet in which oxide particles including the X atoms and having a volume change ratio of 0.99 or lower with respect to an oxide film before brazing heating are formed on a surface thereof, by brazing heating.