Glossary Terms for

Welding

Welding is the process of joining two or more metal parts by melting the base materials and adding filler metal to form a strong, permanent bond. The terms below cover welding processes, joint types, weld quality, codes and certifications, and the techniques used in structural and precision fabrication welding.

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AWS (American Welding Society)
The primary standards organization for the welding industry in North America, responsible for welding codes, certifications, and specifications.
Base Metal
The material being welded, as opposed to the filler metal added during the process.
Butt Joint
A weld joint configuration in which two pieces of metal are placed edge-to-edge in the same plane.
Complete Joint Penetration (CJP)
A weld in which the weld metal completely fills the joint and achieves full fusion through the entire material thickness.
Distortion (Weld)
The dimensional change or warping of the base metal caused by non-uniform thermal expansion and contraction during welding.
Filler Metal
The metal added to the weld joint during fusion welding, typically in the form of wire or electrode.
Fillet Weld
A weld that joins two surfaces meeting at approximately 90 degrees without joint preparation.
Fixture (Welding)
A device used to hold, position, and restrain workpieces during welding to control distortion and maintain dimensional accuracy.
Flux-Cored Arc Welding (FCAW)
A wire-feed welding process using a tubular electrode with a flux-filled core.
Gas Metal Arc Welding (GMAW/MIG)
A welding process that feeds a continuous solid wire electrode through a welding gun while a shielding gas protects the weld pool from atmospheric contamination.
Gas Tungsten Arc Welding (GTAW/TIG)
A welding process using a non-consumable tungsten electrode and inert shielding gas to produce high-quality, precise welds.
Groove Weld
A weld deposited in a groove formed between two joint members.
Heat Input
A calculated measure of the welding energy delivered per unit length of weld, combining current, voltage, and travel speed.
Heat-Affected Zone (HAZ) Welding
The area of base metal adjacent to the weld that has not melted but has experienced microstructural changes from welding heat.
Lap Joint
A weld joint in which two overlapping pieces of material are joined, typically with fillet welds on one or both sides.
Partial Joint Penetration (PJP)
A weld in which the weld metal does not penetrate through the full joint thickness.
Porosity
A weld discontinuity characterized by gas pockets or voids trapped in the solidifying weld metal.
Post-Weld Heat Treatment (PWHT)
A controlled heating and slow-cooling process applied to welded assemblies to relieve residual stresses, improve toughness, and restore material properties after welding.
Root Pass
The initial weld pass deposited at the root of a joint.
Shielding Gas
A gas or gas mixture, such as argon, CO2, helium, or blended mixtures, used during welding to displace atmospheric oxygen and nitrogen from the weld zone and prevent oxidation of the molten weld pool.
Spatter
Molten metal droplets expelled from the welding arc that solidify on the base metal surface outside the weld zone.
Structural Weldment
A fabricated assembly made by welding multiple individual components together to form a structural part or framework.
T-Joint
A weld joint configuration in which one piece of metal is positioned perpendicular to another, forming a T shape.
Tack Weld
A small, temporary weld used to hold components in their correct position prior to final welding.
Weld Certification
Documentation confirming that a welding procedure specification or individual welder qualification has been tested and meets requirements of a specified welding code such as AWS D1.1 or ASME Section IX.
Weld Inspection
Evaluation of completed welds to verify conformance to specified quality requirements.
Weld Joint
The configuration and geometry of the interface between two or more pieces to be welded.
Weld Procedure Specification (WPS)
A written document defining the welding variables including base metal, filler metal, shielding gas, preheat, heat input, and technique for producing a weld meeting specific mechanical property requirements.
Weld Seam
The line of fusion between the base metal and weld metal along the length of a completed weld.
Weldment
A finished assembly produced by joining two or more metal parts by welding.

Glossary Term Categories

Laser Cutting
Press Braking
Welding
CNC Shearing
Metal Finishing
CNC Machining
NEMA Enclosures
Weldments, Bollards & Guards

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