Welding Glossary

A comprehensive guide to welding terminology, processes, and techniques. This glossary provides clear definitions of common terms used in welding to help both beginners and experienced welders better understand the craft.

A

Air Carbon Arc Cutting (CAC-A)Process

Process for cutting metals using an arc and compressed air to remove molten metal.

AmperageParameters

The amount of electric current flowing through the welding circuit, measured in amperes (A). Controls penetration depth and melting rate.

Arc LengthTechnique

The distance between the tip of the electrode and the weld pool surface. Affects voltage and heat input.

B

Backstep WeldingTechnique

A technique where weld segments are deposited in the opposite direction to the overall welding progress, reducing distortion.

Base MetalMaterials

The metal parts being joined by welding, also called parent metal or workpiece.

Bevel AngleJoint Preparation

The angle of the prepared edge of a joint, measured from a line perpendicular to the surface.

C

Cap PassTechnique

The final pass in a multi-pass weld, providing the visible surface appearance.

Cold LapDefects

A weld discontinuity where the weld metal fails to properly fuse with the base metal or previous weld pass.

CrackDefects

A fracture-type discontinuity characterized by a sharp tip and high ratio of length and width to opening displacement.

Critical TemperatureMetallurgy

The temperature at which steel begins to transform from one crystalline structure to another, affecting its properties.

D

DCENPower

Direct Current Electrode Negative (straight polarity). Concentrates more heat in the workpiece for deeper penetration.

DCEPPower

Direct Current Electrode Positive (reverse polarity). Provides better cleaning action and shallower penetration.

DefectQuality

A discontinuity or discontinuities that by nature or accumulated effect render a part or product unable to meet minimum applicable acceptance standards or specifications.

DiscontinuityQuality

An interruption in the typical structure of a weld, such as lack of homogeneity in mechanical, metallurgical, or physical characteristics.

DistortionProcess Effects

Warpage or dimensional change in a weldment due to the heating and cooling cycle of welding.

Duty CycleEquipment

The percentage of time in a 10-minute period that a power source can operate at rated output without overheating.

E

E6010Consumables

A cellulosic covered electrode for SMAW, providing deep penetration and commonly used for root passes.

ElectrodeEquipment

The component that conducts electrical current and may or may not provide filler metal to the weld.

Electrode CoatingConsumables

The flux covering on a stick electrode that provides arc stability, shielding, and alloying elements.

F

FCAWProcess

Flux Cored Arc Welding - uses a continuous tubular wire filled with flux materials.

Fillet WeldJoint Types

A weld of approximately triangular cross section joining two surfaces at approximately right angles.

Flat PositionPosition

The welding position where welding is performed from the upper side with the weld axis approximately horizontal.

G

GMAWProcess

Gas Metal Arc Welding (MIG) - uses a continuous wire electrode and external gas shielding.

Groove WeldJoint Types

A weld made in a groove between two members to be joined.

GTAWProcess

Gas Tungsten Arc Welding (TIG) - uses a non-consumable tungsten electrode and external gas shielding.

H

HAZMetallurgy

Heat Affected Zone - the portion of base metal whose properties or microstructure have been altered by welding heat.

Hot PassTechnique

The second pass in a multi-pass weld, applied immediately after the root pass.

I

InclusionDefects

Entrapped foreign solid material, such as slag, flux, or oxide, in the weld metal or between weld and base metal.

InspectionQuality

The process of examining welds to determine their quality and conformance to specified requirements.

J

Joint PenetrationQuality

The distance the weld metal extends from the weld face into a joint, exclusive of reinforcement.

L

Lack of FusionDefects

A weld discontinuity where fusion did not occur between weld metal and base metal or between adjoining weld beads.

Lap JointJoint Types

A joint between two overlapping members.

M

MartensiteMetallurgy

A hard, brittle microstructure formed in steel by rapid cooling from high temperature.

N

Non-Destructive Testing (NDT)Quality

Inspection methods that do not damage the part being tested, such as visual, penetrant, magnetic particle, or ultrasonic testing.

O

Overhead WeldPosition

A weld made from the underside of a joint.

P

Penetrant Testing (PT)Quality

A non-destructive method using penetrating liquid and developer to reveal surface discontinuities.

PorosityDefects

Cavity-type discontinuities formed by gas entrapment during solidification.

R

Residual StressProcess Effects

Stress remaining in a structure or member as a result of thermal or mechanical treatment.

Root FaceJoint Preparation

That portion of the groove face adjacent to the root of the joint.

Root GapJoint Preparation

The separation between members at the root of the joint.

Root PassTechnique

The first pass in a multi-pass weld joint.

S

SMAWProcess

Shielded Metal Arc Welding (stick welding) - uses a covered electrode that provides both filler metal and shielding.

Stitch WeldingTechnique

Intermittent welding in which the weld lengths are longer than the unwelded spaces.

Stringer BeadTechnique

A weld bead made without appreciable weaving motion.

T

Travel AngleTechnique

The angle between the electrode axis and a line perpendicular to the weld axis, in the direction of travel.

U

UndercutDefects

A groove melted into the base metal adjacent to the weld toe and left unfilled by weld metal.

V

V-GrooveJoint Types

A joint preparation where the edges of two parts are beveled to form a V-shaped groove.

Vertical WeldPosition

A weld made in a vertical position, either upward or downward.

W

Weave BeadTechnique

A type of weld bead made with transverse oscillation.

Weld SequenceTechnique

The order in which weld passes or weld segments are made.

Weld SymbolDocumentation

A standardized symbol placed on drawings to indicate the type, size, and other requirements for a weld.

Work AngleTechnique

The angle between the electrode axis and a line perpendicular to the weld axis, across the direction of travel.

Z

Zinc CoatingMaterials

A protective layer often found on galvanized steel that requires special consideration during welding.