Aluminum alloy welding wire

Abstract

A composition for welding or brazing aluminum comprises silicon (Si) and magnesium (Mg) along with aluminum in an alloy suitable for use in welding and brazing. The Si content may vary between approximately 4.7 and 10.9 wt %, and the Mg content may vary between approximately 0.15 wt % and 0.50 wt %. The alloy is well suited for operations in which little or no dilution from the base metal affects the Si and / or Mg content of the filler metal. The Si content promotes fluidity and avoids stress concentrations and cracking. The Mg content provides enhanced strength. Resulting joints may have a strength at least equal to that of the base metal with little or no dilution (e.g., draw of Mg). The joints may be both heat treated and artificially aged or naturally aged.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a Non-Provisional of U.S. Provisional Patent Application No. 61 / 303,149, entitled “Aluminum Alloy Welding Wire”, filed Feb. 10, 2010, which is herein incorporated by reference.BACKGROUND[0002]The invention relates generally to the field of welding filler metals, and more particularly to compositions suitable for welding aluminum alloys.[0003]Many different processes are known and currently in use for joining metal articles, including brazing and welding. Both such operations may be used for joining of aluminum and aluminum alloy articles. Unlike steels and other metals, aluminum alloys present unique problems owing, for example, to their metallurgy, their melting points, the changes in strength as a function of particular alloying agents, and so forth. Moreover, increasing interest in both thinner aluminum alloy workpieces on one hand, and thicker workpieces on the other presents additional difficulties in the selectio...

AI Technical Summary

Benefits of technology

[0008]In accordance with one aspect, the invention provides a composition for forming weld or braze joints, comprising silicon in a weight percent of between approximately 4.7% inclusive and 10.9% inclusive, magnesium in a weight percent of between approximately 0.15% inclusive and 0.50% inclusive and a remainder of aluminum and trace components. Particular subranges of these are particularly attractive for their enhanced performance and superior strength. Moreover, the invention provides a filler metal product for welding or brazing that comprises a spooled or linear wire or rod comprising an alloy of silicon in a weight percent of between approximately 4.7% inclusive and 10.9% inclusive, magnesium in a weight percent of between approximately 0.15% inclusive and 0.50% inclusive, and a remainder of aluminum and trace components.

[0009]In accordance with another aspect, the invention offers a method for forming a weld or braze joint, comprising melting at least a portion of a work piece base metal, adding to the melted base metal a filler metal comprising an alloy of silicon in a weight percent of between approximately 4.7% inclusive and 10.9% inclusive, magnesium in a weight percent of between approximately 0.15% inclusive and 0.50% inclusive, and a remainder of aluminum and trace components, and allowing the resulting weld or braze joint to solidify. Here again, certain processes and subranges are particularly attractive for their performance and strength properties. This invention is also intended to cover joints and structures made by the new methods and materials provided.

Problems solved by technology

Unlike steels and other metals, aluminum alloys present unique problems owing, for example, to their metallurgy, their melting points, the changes in strength as a function of particular alloying agents, and so forth.

Moreover, increasing interest in both thinner aluminum alloy workpieces on one hand, and thicker workpieces on the other presents additional difficulties in the selection of brazing and welding materials that perform well and provide the desired physical and mechanical properties.

The temperatures used in brazing may anneal both non-heat treatable and heat treatable aluminum alloys, which may alter the mechanical properties achieved either by cold working or heat treatment and aging operations.

Therefore, brazing, while quite useful in many applications, may not be suitable to join high strength structural alloys.

Currently available aluminum alloy brazing and welding wires do not, however, satisfy the needs of many modern applications.

For example, current products do not offer the desired fluidity during the joining operation, or the desired strength when combined with base material in welding applications, particularly when used with a range of modern welding processes.

Moreover, where welding arcs vary in penetration, heat, weld pool formation, and so forth, current aluminum alloy wires and compositions do not provide a desired degree of consistency in terms of the composition and strength of the ultimate joint.

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