WELDING TERMS AND DEFINITIONS
Ductility A metal’s ability to be drawn, stretched, or formed without breaking.
Electrical Conductivity A metal’s ability to conduct an electrical current.
Electrode A device that conducts electricity. In arc welding, the electrode also can act as the filler metal.
Ferrous Metal A metal that contains iron. Steel is the most popular ferrous metal.
Filler Metal A type of metal sometimes added to the joint in fusion welding. Filler metal adds to the
strength and mass of the welded joint.
Galvanizing The process of adding a zinc coating to steel. Galvanized steel is used to manufacture car
parts, building frames, and ducting.
Gas Torch A device that emits heat in the form of a gas.
Gauge A standard of measure used to determine a specific thickness of sheet metal.
Grain Structure The relationship between the small, individual crystals in an alloy or metal.
Grinding The use of an abrasive to wear away at the surface of a workpiece.
Hardness A metal’s ability to resist indentation, penetration, and scratching. The heat from welding may
change a metal’s hardness.
Heat Treatment The controlled heating and cooling processes used to change the structure of a material
and alter its mechanical and physical properties.
Heat-affected Zone The portion of the base metal that has not been melted, but its mechanical properties
have been altered by the heat of welding.
Magnesium A grayish white, extremely light metal that is also brittle and has poor wear resistance.
Magnum Gun MIG welding guns and TIG welding torches are hand-held welding application tools
connected to both the wire feeder and power source. They direct the welding wire to the weld joint and
control the wire feed with the use of a trigger mechanism.
Mechanical Properties The properties that describe a material’s ability to compress, stretch, bend,
scratch, dent or break.
Melting Temperature The temperature necessary to change a metal from solid to a liquid. Also known as
a melting point.
MIG Welding Constant Voltage and Constant Current welders are used for MIG welding and are a
semi-automated process when used in conjunction with a wire feeder. Wire is fed through a gun to the
weld-joint as long as the trigger is depressed. This process is easier to operate than stick welding and
provides higher productivity levels. CC/CV welders operate similarly to CC (MIG) welders except that
they possess multi-process capabilities – meaning that they are capable of performing flux-cored, stick
and even TIG processes as well as MIG.
Nickel A hard, malleable, silvery white metal used in various alloys to add strength, toughness, and
impact resistance to metals.
Nonferrous Metal A metal that does not contain iron. Aluminum and copper are common nonferrous
Non-heat Treatable Alloy Alloys that rely primarily on cold working to increase their strength properties.
Oxyfuel Gas Cutting Oxyfuel gas cutting process involves preheating the base metal to a bright cherry
red, then introducing a stream of cutting oxygen which will ignite and burn the metal.
Physical Properties The properties that describe a metal’s ability to melt, emit heat, conduct electricity,
and expand or shrink.
Post heating The application of heat to the weld immediately after welding. Post heating helps to reduce
stress in the weld metal.
Plasma Cutter A constricted cutting arc is created by this machine, which easily slices through metals. A
high-velocity jet of ionized gas removes molten material from the application.
Precipitate The separation of elements from a type of solution. Elements that precipitate out of a solution
change a metal’s properties.
Precipitation Hardening The process of heating to a temperature at which certain elements precipitate,
forming a harder structure, and then cooking at a rate to prevent a return to the original structure.
Preheating The application of heat to a base metal immediately before welding. Preheating helps reduce
hardness in the metal.
Properties A characteristic of material that distinguishes it from other materials.
Quality Assurance Quality Assurance (QA) is a set of defined processes and actions for systematic monitoring
and evaluation to ensure a safe, effective, and high-quality product.
Quality Control Quality control (QC) is the set of test procedures used to verify that a product meets the
manufacturing specifications. It involves checking and testing both the manufacturing procedures and
the quality of the final products.
Recrystallization The formation of a new grain structure. Recrystallization is often the result of annealing.
Robotic Welding The combination of a robotic arm, a welding power source and a wire feeder produces
welds automatically using various programs, welding fixtures and accessories.
Silicon A nonmetallic element often found in sand and used to make glass. High amounts of silicon in a
weld can cause cracking.
Stick Electrode A short stick of welding filler metal consisting of a core of bare electrode covered by
chemical or metallic materials that provide shielding of the welding arc against the surrounding air. It
also completes the electrical circuit, thereby creating the arc. (Also known as SMAW, or Stick Metal Arc
Stick Welding Heating the coated stick electrode and the base metal with an arc creates fusion of metals.
An AC and/or DC electrical current is produced by this machine to create the heat needed. An electrode
holder handles stick electrodes and a ground clamp completes the circuit.
Solution Heat Treating 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
Steel A metal consisting of iron and carbon, usually with small amounts of other elements. Steel is the
most common manufacturing metal.
Strength A meal’s ability to resist outside forces that are trying to break or deform the metal.
Supersaturated Solution A solution that is completely filled with alloying elements.
Tack Weld A weld made to hold the parts of a weld in proper alignment before the final welds are made.
Tack welds are also used to aid in preheating.
Tensile Strength A metal’s ability to resist forces that attempt to pull it apart or stretch it.
Thermal Conductivity The rate at which heat flows through metal.
Thermal Expansion The increase in the dimensions of a metal due to an increase in its temperature
TIG Welding A less intense current produces a finer, more aesthetically pleasing weld appearance.
A tungsten electrode (non-consumable) is used to carry the arc to the workpiece. Filler metals are
sometimes supplied with a separate electrode. Gas is used for shielding. (Process is also known as GTAW,
or Gas Tungsten Arc Welding.)
Tin A silver-white soft metal used in many alloys. Tin is often used to coat other metals to prevent corrosion.
Titanium A silver-gray, strong, but lightweight metal known for its corrosion resistance. Titanium is often
used in the aerospace industry.
Toughness A metal’s ability to withstand a sharp blow.
Weave Movement of the electrode in a back and forth motion to deposit weld metal into a joint.
Weld A mix of metals that joins at least two separate parts Welds can be produced by applying heat, or
pressure, or both heat and pressure, and they may or may not use an additional filler metal.
Weldability The ability of a material to be welded under imposed conditions into a specific, suitable
structure and to perform satisfactorily for its intended use.
Wrought Nickel Alloy An alloy containing nickel that has been bent, hammered, or physically formed
into a desired shape. Wrought nickel alloys are often welded under the same conditions as certain types
Yield Strength A metal’s ability to resist gradual progressive force without permanent deformation.
Zinc A bluish white metal that is corrosive resistant and has a relatively low melting point. Zinc is often
used as a coating on steel.