AWS D17.1 Endorsement key terms

The American Welding Society specification that sets qualification and inspection requirements for fusion welding of aerospace hardware, covering design, procedure and performance qualification, fabrication, and examination.

A standard written for flight and ground-support hardware where joint integrity, documentation, and traceability are more demanding than general structural welding codes, so acceptance limits and qualification rules are stricter.

Any welding process that joins metal by melting the faying surfaces, with or without filler metal, so the completed joint contains a melted and resolidified zone rather than only pressure bonding.

A written, qualified document listing every essential and nonessential variable for a production weld, including process, base metal, filler, joint design, preheat, and electrical parameters, so the welder can reproduce an approved result.

The documented record of the test weld made to qualify a welding procedure, capturing actual variables used and the results of mechanical and nondestructive testing that support the WPS.

A welding condition, such as process, base metal group, filler classification, or heat input range, that if changed beyond the allowed limit requires requalification of the procedure because it can alter joint properties.

A welding condition that may be changed without requalifying the procedure, provided the WPS is revised, because the change does not measurably affect the mechanical properties of the completed joint.

Testing of an individual welder on a representative test joint to demonstrate the skill needed for a specific process, position, and thickness range before that welder may work on production aerospace hardware.

Written confirmation by the fabricator that a welder has passed the required performance qualification tests and is authorized to weld under a defined scope, subject to records retention and periodic requalification.

Retained documents, including WPS, PQR, and welder test results, that prove procedures and personnel were qualified and that allow traceability during audits or failure investigations.

The material being joined by welding, whose composition, thickness, and condition determine preheat needs, filler selection, and the qualification grouping used in the specification.

The consumable wire, rod, or electrode added to a weld to supply the deposited metal, specified by classification so that strength, ductility, and corrosion behavior match the design requirement.

The metal added during welding that becomes part of the joint, whose chemistry and mechanical properties must meet the specification limits for the application.

The portion of base metal melted into the weld pool that mixes with filler metal, changing the final deposit chemistry and potentially reducing strength or corrosion resistance if excessive.

The localized volume of molten metal at the joint during welding, whose size and fluidity are controlled by heat input, travel speed, and shielding to shape the finished bead.

Energy delivered per unit length of weld, usually calculated from voltage, current, and travel speed, which controls cooling rate, grain structure, distortion, and the resulting mechanical properties.

The temperature of the joint immediately before the next pass is deposited, kept within a specified maximum to avoid overheating, loss of strength, or excessive grain growth in the weld and heat-affected zone.

The base metal adjacent to the fusion line that was not melted but was altered by welding heat, often the site of hardness changes, cracking, or reduced ductility in aerospace alloys.

The boundary between melted weld metal and unmelted base metal, used as a reference for measuring penetration and for locating discontinuities such as lack of fusion.

The depth to which the weld extends into the joint from the original surface, which must meet design requirements because insufficient penetration weakens the joint while excessive penetration can damage thin sections.

The geometric arrangement of parts to be welded, such as butt, lap, tee, or corner, together with edge preparation and fit-up, which governs access, penetration, and the applicable acceptance criteria.

The alignment and gap control of parts before welding, which must stay within drawing and specification tolerances because poor fit-up causes distortion, incomplete fusion, and out-of-tolerance final dimensions.

Unintended change in shape or dimensions of a welded assembly caused by uneven heating, shrinkage, and residual stress, controlled through sequencing, fixturing, and balanced welding techniques.

Internal stress locked into a weldment after cooling because restrained contraction prevented the material from relaxing, which can promote cracking, reduce fatigue life, or cause movement during machining.

A controlled thermal treatment applied after welding to reduce residual stress by allowing the material to relax at elevated temperature without significantly altering its specified strength.

Any controlled heating applied after welding, including stress relief or aging, performed under a qualified procedure with monitored temperature and time to achieve the intended metallurgical result.

Heating the base metal before welding to slow cooling, drive off moisture, and reduce cracking risk in alloys sensitive to rapid thermal gradients or hydrogen pickup.

Gas supplied around the arc or weld zone to exclude atmospheric oxygen and nitrogen, protecting the molten metal from contamination that would cause porosity or embrittlement.

An interruption in the normal structure of a weld, such as porosity, a crack, or incomplete fusion, which may or may not be a defect depending on whether it exceeds the acceptance criteria.

A discontinuity or flaw that exceeds the acceptance limits of the applicable specification and therefore requires disposition, such as rework, repair, or rejection of the part.

The stated limits, sizes, and types of discontinuities permitted in a weld, used by the inspector to decide whether a part is acceptable without further engineering disposition.

Void cavities trapped in solidified weld metal, typically caused by gas that could not escape the molten pool, appearing as rounded internal or surface openings on radiographs or visual inspection.

A condition where weld metal did not fully bond to the base metal or to a previous pass, leaving a planar discontinuity that sharply reduces joint strength and is often hard to detect.

A discontinuity where the weld does not extend through the full joint depth required by design, leaving an unwelded root region that acts as a stress concentrator.

A planar separation in weld or base metal that is generally unacceptable in aerospace hardware because it propagates under cyclic loading and signals a serious metallurgical or process problem.

The primary inspection method in which the finished weld is examined by eye or aided vision for surface discontinuities, bead shape, cleanliness, and dimensional conformity before other testing is chosen.

A surface inspection method that applies a liquid dye or fluorescent penetrant to reveal open surface-breaking discontinuities such as cracks and pores after excess penetrant is removed and developer is applied.

A volumetric nondestructive method that passes radiation through the weld to record internal density differences, revealing porosity, inclusions, and lack of fusion on film or digital images.

A volumetric nondestructive method that sends high-frequency sound into the weld and interprets echoes to detect and size internal planar discontinuities such as cracks and incomplete fusion.

A representative welded specimen produced for qualification or production-control testing, from which specimens are cut for mechanical tests and nondestructive examination.

A mechanical test that pulls a specimen until it fractures to measure strength and ductility, used to confirm that a qualified procedure produces joints meeting design requirements.

The documented ability to link finished hardware to its base metal lot, filler lot, qualified procedure, welder, and inspection records, supporting quality audits and failure analysis.