BACKGROUND

The present disclosure relates to a metal-cored welding wire, and, more specifically, to a metal-cored aluminum welding wire for arc welding, such as Gas Metal Arc Welding (GMAW) and Gas Tungsten Arc Welding (GTAW).

Aluminum and aluminum alloys are widely used as construction material due to their relatively low density and high corrosion resistance compared to other metals. For example, aluminum alloys may provide strengths between approximately 50 megapascal (MPa) and approximately 700 megapascal (MPa). For construction applications, aluminum materials are typically joined by means of welding. Since aluminum has a high affinity for oxygen, aluminum welding typically involves the use of an inert shielding gas to limit or prevent the formation of aluminum oxide (alumina) and undesirable inclusions.

Typical aluminum welding wires are solid wires. These solid wires are generally produced by continuously casting and subsequent rolling an alloy to form a rod having a predetermined diameter. The resulting rod may then be drawn through a number of dies to reduce the diameter and form an aluminum welding wire of the desired size. Since the composition of an aluminum welding wire is generally selected to closely match the composition of the workpiece, producing certain aluminum welding wires in this way can be problematic for certain alloys of aluminum that are not well-suited for drawing.

One problem in aluminum welding is weld porosity. It is generally desirable for welds to have a low porosity, and the porosity observed in aluminum welds may be caused by a number of sources. One prominent source of such pores is hydrogen that is released from, and forms voids within, the solidifying weld metal. Hydrogen gas may be formed via the decomposition of hydrogen-containing materials (e.g., moisture or organic materials, such as lubricants) near the welding arc. As such, it is desirable to prevent hydrogen-containing materials from being introduced into the welding environment.

Alloys reinforced by nanoparticles have gained interest in recent years due to the novel physical and chemical properties that such alloys often have. Nanoparticles may exhibit physical and chemical properties that differ from the corresponding microparticles and bulk materials, providing more effective options for many applications in various fields. For example, nanoparticles can be used in surface engineering to improve the abrasive wear resistance or to affect the tribological properties of lubricants; in electronic applications to change such properties as electrical conductivity, strength, and magnetic properties; and in welding or additive manufacturing applications to improve the mechanical properties such as Young's modulus, tensile strength, hardness, and fatigue strength.

BRIEF DESCRIPTION

In an embodiment, a metal-cored aluminum welding wire includes a metallic sheath and a granular core disposed within the metallic sheath. The granular core includes a first alloy having a plurality of elements, wherein the first alloy has a solidus that is lower than each of the respective melting points of the plurality of elements of the first alloy. The granular core includes aluminum metal matrix nano-composites (Al-MMNCs) that comprise an aluminum metal matrix and ceramic nanoparticles. The ceramic nanoparticles may have an average particle size of between 25 and 250 nm.

In an embodiment, a method of manufacturing a metal-cored aluminum welding wire includes disposing a granular core within a metallic sheath. The granular core includes Al-MMNCs that comprise an aluminum metal matrix and ceramic nanoparticles. The granular core includes a first alloy comprising a plurality of elements, wherein the first alloy has a solidus that is lower than each of the respective melting points of the plurality of elements of the first alloy.

In an embodiment, a method of welding includes forming a weld pool on a workpiece using a metal-cored aluminum welding wire, wherein the metal-cored aluminum welding wire comprises a granular core disposed within a metallic sheath. The granular core includes a first alloy comprising a plurality of elements, wherein the first alloy has a solidus that is lower than each of the respective melting points of the plurality of elements of the first alloy. The granular core includes Al-MMNCs that comprise an aluminum metal matrix and ceramic nanoparticles.

