alloy A metal consisting of a mixture of two or more materials. One of these materials must be a metal.
alloy steel A steel that contains intentionally added materials, which change the property of the metal. Common alloy elements include chromium, manganese, molybdenum, and nickel.
aluminum A silvery white metal that is soft, light, and an effective conductor.
arc welding A fusion welding process that uses electricity to generate the heat needed to melt the base metals.
austenitic stainless steel Stainless steel with very high strength, as well as excellent ductility and toughness. Austenitic stainless steel is the most corrosion resistant stainless steel.
base metal One of the two or more metals to be welded together to form a joint.
carbon A common, non-metallic element found in all types of steel. Carbon is the main hardening element in steel.
carbon steel A steel that is made up of iron and carbon, without any additional materials.
chromium A shiny, hard, steel-gray metal that increases the hardenability and corrosion resistance of steel. Stainless steels also contain large amounts of chromium.
chromium oxide A protective film that develops on the surface of stainless steel and helps prevent corrosion.
compressive strength The ability of a metal to resist forces that attempt to squeeze or crush it.
copper A reddish metal that is very ductile, thermally and electrically conductive, and corrosive resistant. Copper is often used to make electrical wire.
corrosion The gradual chemical attack on a metal by atmosphere, moisture, or other agents.
corrosion resistance The ability of a metal to resist attack by other elements and chemicals.
crystal structure The regular, repeating pattern of atoms in a metal. Crystal structures develop as a metal solidifies.
distortion Warpage in the base metal due to stresses caused by heating it to expansion and then cooling it to contraction.
ductility A metal's ability to be drawn, stretched, or formed without breaking.
electrical conductivity The ability of a metal to conduct an electrical current.
electrode A device that conducts electricity. In welding, the electrode also can act as the filler metal.
ferritic stainless steel Stainless steel that contains mostly chromium and has low carbon content. Ferritic stainless steels are easy to weld and not hardenable by heat treatment.
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.
gas metal arc welding An arc welding process in which the bare wire electrode and inert shielding gas are fed to the weld through a welding gun. It is also referred to as GMAW or MIG welding.
gas torch A device that emits heat in the form of a gas. Gas torches are used to preheat base metals.
gas tungsten arc welding A very precise arc welding process that uses a nonconsumable tungsten electrode. It is also referred to as GTAW or TIG welding.
grain growth The expansion of the individual crystals in a metal. Grain growth results in a loss of toughness.
grain structure The relationship between the small, individual crystals in a metal or alloy.
hardenability The ability of a metal to be hardened by normal heat treatment processes.
hardness The ability of a metal 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 physical and mechanical properties.
heat-affected zone The portion of the base metal that has not been melted but with mechanical properties have been altered by the heat of welding.
high-carbon steel A carbon steel that contains more than 0.5% carbon. These steels are extremely strong, hard, and always require heat treatment for effective welding.
hydrogen A gas that is the lightest and most abundant element in the universe. Too much hydrogen near the weld metal can cause cracking.
internal porosity Porosity that occurs within a particular metal.
iron The fourth most abundant earth element. Iron is alloyed with carbon to make steel.
joint The meeting point of the two materials that are joined together. Welding creates a permanent joint.
joint penetration The minimum depth that a groove weld extends into the face of a joint.
low-carbon steel A carbon steel that contains less than 0.30% carbon. These steels are generally tough, ductile, and easily welded.
magnesium A grayish white, extremely light metal that is also brittle and has poor wear resistance.
manganese A hard, brittle, gray-white metal that increases the hardenability of steel. Manganese also increases strength and hardness.
martensitic stainless steel Stainless steel that is stronger than ferritic stainless steel but less corrosion resistant. Martensitic stainless steels are hardenable by heat treatment.
mechanical properties The properties that describe a material's ability to compress, stretch, bend, scratch, dent, or break.
medium-carbon steel A carbon steel that contains between 0.30% and 0.45% carbon. These steels are strong, hard, and not as easily welded as low-carbon steels.
melting temperature The temperature necessary to change a metal from solid to a liquid. Also known as melting point.
mild steel Another name for low-carbon steel.
molybdenum A metallic alloying element commonly used to increase hardenability in carbon and alloy steels and to enhance corrosion resistance in stainless steels.
nickel A hard, malleable, silvery white metal used in ferrous alloys to add strength, toughness, and impact resistance to steel.
nonferrous metal A metal that does not contain iron. Aluminum and copper are common nonferrous metals.
oxygen A colorless, odorless, tasteless gas that naturally exists in the atmosphere. In welding, too much oxygen causes cracking and rusting in the metals.
physical properties The properties that describe a material's ability to melt, emit heat, conduct electricity, and expand or shrink.
porosity Cavity type discontinuities or bubbles formed by gas entrapment during solidification of the weld metal.
post heating The application of heat to the weld immediately after welding. Post heating helps reduce stress in the weld metal.
preheating The application of heat to a base metal immediately before welding. Preheating helps reduce hardness in the metal.
properties A characteristic of a material that distinguishes it from other materials.
shielded metal arc welding An arc welding process that uses a flux-coated rod. It is also referred to in the shop as SMAW or stick welding.
stainless steel A type of steel that contains more than 15% chromium and exhibits excellent corrosion resistance.
steel A metal consisting of iron and carbon, usually with small amounts of other elements. Steel is the most common manufacturing metal.
strength A metal's ability to resist outside forces that are trying to break or deform the metal.
tensile strength The ability of a metal to resist forces that attempt to pull 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.
toughness A metal's ability to withstand a sharp blow without breaking.
V-groove An opening between two part surfaces, shaped like the letter "V" that provides space to contain weld metal.
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 satisfactory for its intended use.
yield strength The ability of a metal to tolerate gradual progressive force without permanent deformation