Arc Welding Aluminum Alloys 310

This class describes the welding characteristics of aluminum and explains how its properties affect each variable in the welding process.

  • Difficulty Advanced

  • Format Online

  • Number of Lessons 21

  • Language English


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Course Outline
  • Objectives
  • Properties of Aluminum
  • Aluminum Alloy Classifications
  • Aluminum Alloying Elements
  • Joint Design
  • Cleaning Aluminum
  • Preheating Aluminum
  • Power Sources for Aluminum
  • Welding Aluminum with DC
  • Welding Aluminum with AC
  • Using the Inverter
  • Electrode Selection
  • Filler Metal Selection
  • Shielding Gas Selection
  • Welding Aluminum with GTAW
  • Welding Aluminum with GMAW
  • Metal Transfer Mode
  • Feeding Aluminum Wire
  • Types of Wire Feeders
  • Common Defects in Aluminum
  • Summary
  • Describe the properties of aluminum.
  • Distinguish between wrought alloy and cast alloy designations.
  • Classify common aluminum alloying elements according to their weldability.
  • Describe common joint designs for aluminum.
  • Explain the methods used to clean aluminum.
  • Explain the importance of properly preheating aluminum.
  • Explain the benefits of constant current power sources for welding aluminum.
  • Describe the advantages of using DC on aluminum.
  • Describe the advantages of using AC on aluminum.
  • Explain the advantages of using an inverter for welding aluminum.
  • Explain how to select an electrode for GTAW.
  • Explain how to select an electrode for GMAW.
  • Describe factors to consider when selecting a filler alloy for aluminum.
  • Describe factors to consider when selecting a shielding gas for aluminum.
  • Explain the steps necessary to prepare for welding aluminum with GTAW.
  • Explain the steps necessary to prepare for welding aluminum with GMAW.
  • Explain the appropriate metal transfer modes for welding aluminum.
  • Describe the specialized equipment required for feeding aluminum wire.
  • List the types of wire feeders used for aluminum.
  • Identify common defects found in aluminum welds.
Vocabulary Term

AC wave balance

A control on the welder, which allows an operator to manually adjust the oxide removal and weld penetration cycles.

alternating current

Current that regularly reverses the direction of its flow. AC is often used in GTAW to weld aluminum alloys.


A silvery white metal that is soft, light, and an effective conductor.


The steady heating of a metal at a certain temperature followed by a gradual cooling process. Annealing is often used when welding nonferrous metals.


A chemical process, which produces an oxide film or coating on the surface of aluminum alloys to improve corrosion resistance.


An inactive gas commonly used for shielding. Argon is much heavier than air, thus it effectively shields the weld area.


An electrode preparation process in which the tip of the tungsten electrode is formed into a hemispherical ball. This shape is required for AC and DCEP welding.

bird nesting

The tangling of filler wire in a wire feeder, usually caused by resistance in the drive rolls.


Excessive melt through or a hole in the base metal. Extremely high welding temperatures can cause burnthrough.

carbon dioxide

An active gas commonly used as shielding for GMAW. Carbon dioxide is inexpensive but yields a violent arc.

cast alloy

An aluminum alloy that is poured as a liquid into a mold and cooled into a solid shape.


An alloying element commonly found in stainless steel to deter corrosion.

cold lap

Lack of fusion, which is the result of applying too cold of a weld to a plate that is too thick. Cold lap is also called incomplete fusion.

cold working

The shaping of metal at temperatures substantially below the point of recrystallization. Cold working adds strength and hardness.

column strength

The ability of a material to remain rigid and maintain its strength.

contact tip

The device located inside the welding gun that conducts electricity to the electrode.


A reddish metal that is very ductile, thermally and electrically conductive, and corrosion resistant. Aluminum-copper alloys generally have poor weldability.

corrosion resistance

A metal's ability to resist attack by other elements and chemicals.

crater crack

A crack in the crater of the weld bead. Crater cracks occur in aluminum welds due to aluminum's high thermal conductivity.


A device attached to the front of the torch body on a GTAW torch that directs inert shielding gas over the weld area.


An abbreviation for direct current electrode positive. DCEP is another way of expressing direct current with reverse polarity.

direct current electrode negative

Direct current with straight polarity. This is often expressed as DCEN.

direct current electrode positive

Direct current with reverse polarity. This is often expressed as DCEP.

drag angle

Moving the electrode along the workpiece opposite the direction of welding. Drag angles can cause porosity in aluminum welds.

drive roll tension

The amount of tightness or pressure that the drive rolls impress on the filler wire. When welding aluminum, drive roll tension should be reduced to prevent crushing of the wire.

drive rolls

Specially designed wheels for various types and sizes of filler wires to facilitate feeding through a wire feeder.

drooper output slope

The slope on a static volt-ampere curve, which graphs the power that a constant current welder produces.

edge notching

The application of indentations on the edges of two base metal parts, using a saw or chisel, to faciliate complete joint penetration.


A wire aluminum electrode often used to weld pure aluminum. ER1100 is the softest wire and requires extra care to ensure good feeding.


A commonly used filler alloy used to weld 5XXX series alloys.


Forced out of something. Wrought alloys are extruded from shapes.

globular transfer

A type of metal transfer in which the electrode produces a large ball of metal when it touches the workpiece. This deposits large amounts of metal into the weld puddle.


The American Welding Society abbreviation for gas metal arc welding.

groove angle

The total angle of the groove in between workpieces. Aluminum welds generally require large groove angles.


The American Welding Society abbreviation for gas tungsten arc welding.

heat-treatable alloy

An alloy that can be heated during or after welding to restore its strength properties. Copper is a common heat-treatable alloy.

helically wound

Wound in the shape of a helix. A helix is a spiral section with a repeating pattern.


An inactive gas commonly used for shielding. Helium is much lighter than air and can escape the weld area quickly.

hot cracking

Cracking in the weld, which results from stress in thin materials during solidification. Copper alloys often experience hot cracking.

hot short

A characteristic or tendency of a material towards brittleness at a range of temperatures. Materials with hot short tendencies do not have enough tensile strength to resist stresses that result from cooling.

hydrated oxide

A chemical compound containing oxygen and water.


A chemical compound containing only hydrogen and carbon. Hydrocarbons often pollute the atmosphere.


The first solidified piece of steel from which other parts are made.

intermittent spray transfer

Another name for pulsed spray transfer.


An arc welding power source that operates at very high frequencies and is much more energy efficient than transformer-based machines.


A material used on the inside of gun cables to decrease friction and wear from the filler wire. Liners for welding aluminum are often made of nylon or Teflon&174;.

machine welding

Welding with equipment that performs the welding operation under the observation and control of a welding operator. Machine welding is also referred to as automatic welding.


A grayish white, extremely light metal that is brittle and has poor wear resistance. Aluminum-magnesium alloys have excellent weldability.


A hard, brittle, gray-white metal that increases the hardenability of steel. Manganese-aluminum alloy are improved through strain hardening.

nonheat-treatable alloy

An alloy that relies primarily on cold working to increase its strength properties. Magnesium is a common nonheat-treatable alloy.

open-circuit voltage

The voltage between the output terminals in the welder when no current is flowing in the welding circuit.

oxide film

A chemical compound that contains oxygen, which forms a thin layer on the surface of metals when exposed to air. Oxide film should be removed before welding.


A colorless, odorless, tasteless gas that naturally exists in the atmosphere. A small amount of oxygen is sometimes used for shielding. However, too much oxygen causes cracking and rusting in the metals.


The direction of current flow in a direct current (DC) circuit.


The appearance of tiny bubbles on a weld bead as a result of gas entrapment. Excessive porosity can weaken a weld.

pulsed spray transfer

A type of metal transfer in which as little as one droplet of metal forms on the end of the electrode during periods of high current, but ceases during periods of low current. Pulsed spray welding reduces the heat input to the base metal, which makes it easier to weld thin aluminum with GMAW.

pure aluminum

A nonheat-treatable element, which contains at least 99% aluminum and no additional alloying elements. Pure aluminum is known for its superior corrosion resistance.

pure tungsten electrode

A type of tungsten electrode made with 99.5 percent tungsten. Pure tungsten electrodes are primarily used with AC for welding aluminum.

push angle

Moving the electrode along the workpiece in the direction of welding. Welding aluminum with GMAW requires a push angle.

push system

A type of wire feeder that consists of a high-torque motor, which pushes the filler wire through the liner to the welding gun. Push systems work best for feeding larger diameter wires.

push-pull system

A wire feeder that consists of two motors, one that pushes the electrode from the feeder and another that pulls the electrode. Push-pull systems offer the advantages of a push system and a spool system.

self-contained gun

A welding gun that feeds filler wire from a spool mounted on the gun and not from a separate wire feeder.

short circuit transfer

A type of metal transfer in which the electrode produces a short circuit and high current when it touches the workpiece. The high current level causes a violent transfer of metal, which creates the weld.


A nonmetallic element often found in sand and used to make glass. Aluminum-silicon alloys increase the fluidity of aluminum.


The measure of how much of a given substance will dissolve in a liquid. Molten aluminum has a high solubility for hydrogen.

solution heat treatment

A heat treatment method used to heat an alloy to a specific temperature for a certain period of time to allow one or more alloy elements to dissolve in a solid solution and then cool rapidly.

spool gun system

A type of wire feeder that consists of a self-contained gun, which feeds filler wire from spools mounted on the gun. Spool guns are mainly used for smaller diameter, softer wires.

spray transfer mode

A type of metal transfer in which the metal at the end of the wire melts into small, fine droplets creating a stable arc and little spatter.

static volt-ampere curve

The type of graph used to chart a welder's voltage output versus its amperage output in a given time period.


A term used to describe electrode extension, or the distance from the end of the contact tip to the end of the electrode.

strain hardening

The increase in the strength and hardness of a metal due to a mechanical deformation in the metal's microstructure. The nonheat-treatable aluminum alloys are commonly strain hardened.

stress corrosion cracking

The failure of metals under the combined action of corrosion and stress.

stringer bead

A type of weld bead formed by moving the electrode straight across the joint. A good stringer bead has good wash-in at the weld toes.

thermal conductivity

The rate at which heat flows through metal.


A force that produces rotation. A push-system wire feeder consists of a high-torque motor.

transition current

The current at which a consumable wire electrode goes from the globular transfer method to the spray transfer method.

vertical up

A welding position in which welding is done with the base metal in a vertical position from the bottom to the top.

weave bead

A weld bead formed by moving the electrode along the joint in a weaving motion.

wire feeder

The device either built inside the welder or set beside the welder that feeds wire to the welding gun.

wrought alloy

An aluminum alloy, which is rolled from an ingot or extruded from customer-specified shapes.


A bluish white metal that is corrosive resistant and has a relatively low melting point. Aluminum-zinc alloys generally have poor weldability.

zirconiated tungsten electrode

A type of tungsten electrode, which contains small amounts of zirconium oxide. Zirconiated tungsten electrodes combine the characteristics of pure tungsten and thoriated tungsten electrodes.