AWS D17.1 Endorsement flashcards
AWS D17.1 Endorsement · Build recall with a focused review session.
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- D17.1 scope
- AWS D17.1 specifies requirements for fusion welding of aerospace hardware, covering base metals such as aluminum, titanium, steel, nickel, cobalt, and magnesium alloys, plus qualification, fabrication, and inspection rules.
- Class A weld
- The most stringent D17.1 inspection class for critical aerospace welds, where failure would endanger personnel or the vehicle. Acceptance limits on porosity and undercut are tightest and full NDE is typically required.
- Class B weld
- A semi-critical D17.1 inspection class with acceptance criteria between Class A and Class C. It applies to welds whose failure would degrade performance but not directly risk safety of flight.
- Class C weld
- The least stringent D17.1 inspection class for non-critical welds. Porosity and profile limits are looser, and examination requirements are typically visual only unless the contract specifies more.
- Procedure qualification record
- The documented evidence that a welding procedure specification produces sound welds. It records the essential variables used and the mechanical or radiographic test results that qualified the procedure.
- Welder performance qualification
- A test in which a welder welds a coupon to a qualified procedure, and the coupon is examined to demonstrate the welder's ability to produce acceptable welds within a defined range.
- Essential variable
- A welding parameter whose change invalidates the existing qualification and requires requalification. Examples include base-metal group, filler classification, process, position, and preheat range.
- Position qualification rule
- Qualifying a welder in a more difficult position, such as vertical or overhead, extends the qualification to easier positions like flat. The reverse is not true and requires separate testing.
- Thickness qualification range
- A test coupon of a given thickness qualifies production thicknesses within a bracketed range defined by the specification table, rather than an unlimited thickness range for the welder.
- Manual welding qualification
- Manual welding depends on welder skill, so a welder performance qualification is required. The welder must remain continuously employed in the process to keep the qualification valid.
- Automatic welding qualification
- Automatic welding is performed by machine with set parameters, so qualification is by procedure and equipment rather than welder skill. A separate procedure qualification is required.
- Semi-automatic welding
- A process where the arc travel is manual but filler feed is mechanized. D17.1 treats it as welder-dependent, so a welder performance qualification is required in addition to procedure qualification.
- Base-metal grouping
- D17.1 groups alloys by composition and weldability for qualification purposes. A procedure qualified on one alloy may extend to other alloys within the same group under stated limits.
- Filler metal control
- Filler metals must meet the applicable AWS filler specification and be stored and handled per manufacturer instructions. Contaminated, expired, or misidentified filler is nonconforming and must not be used.
- Preheat and interpass
- Minimum preheat and maximum interpass temperatures are specified by alloy family. Titanium and some aluminum alloys require tight interpass control to avoid property loss and contamination.
- Visual examination requirement
- Visual examination is mandatory on all completed welds regardless of class. It checks bead profile, undercut, surface porosity, spatter, and arc strikes before other NDE methods are applied.
- Liquid penetrant examination
- A surface NDE method that draws penetrant from surface-breaking discontinuities. It is applied to nonporous materials and is sensitive to surface condition, so rough welds may give false indications.
- Radiographic acceptance
- Radiographic film or digital images are compared to a reference severity standard. Indications at or below the class limit are accepted; larger or denser indications are rejected or repaired.
- Crack rejection rule
- Cracks are rejectable in Classes A and B regardless of size. Under Class C criteria, limited indications may be evaluated for repair or rejection per the specification's stated limits.
- Undercut acceptance
- Undercut is a groove melted into the base metal at the weld toe. Its allowable depth and length depend on the inspection class, with Class A permitting the least undercut.
- Porosity limits
- Porosity acceptance is defined by maximum individual pore size and cumulative length per unit of weld. Limits tighten progressively from Class C to Class B to Class A.
- Incomplete fusion
- A lack of bond between weld metal and base metal or between passes. It is generally rejectable in critical classes because it acts as a stress concentrator and crack initiation site.
- Weld repair procedure
- Repairs must follow a procedure qualified to the same rules as the original weld. The number of repair cycles is limited by the specification and requires engineering approval beyond that limit.
- Post-weld heat treatment
- A controlled heating and cooling cycle applied after welding to relieve residual stress or restore properties. When required, it must follow the qualified procedure and be documented.
- NDE personnel qualification
- Inspection personnel must be certified for the method they perform, typically under a recognized scheme such as NAS 410 or an equivalent employer program, with documented training and experience.
- Welder qualification lapse
- A welder qualification stays valid while the welder remains continuously employed in the qualified process. A lapse beyond six months without that work requires requalification by retest.
- Test coupon joint type
- The joint configuration of the qualification coupon, such as butt or tee, sets which production joint types the welder or procedure is qualified to weld without further testing.
- Contamination control titanium
- Titanium picks up oxygen, nitrogen, and hydrogen at welding temperature, causing embrittlement. Cleanliness, shielding gas coverage, and interpass temperature limits are essential to sound welds.
- Weld documentation package
- The traceable record set for a welded part: the procedure specification, procedure qualification record, welder qualification record, inspection reports, and material certifications, all linked to the part.
- Arc strike
- An accidental arc on the base metal outside the weld zone. It creates a localized heat-affected zone and possible cracking, so it is typically removed and inspected per the specification.
- Heat-affected zone
- Base metal that is metallurgically altered by welding heat but not melted. Its properties may differ from the parent metal and are considered when selecting the procedure and post-weld treatment.
- Cognizant engineering authority
- The organization or individual responsible for approving weld design, procedure deviations, repair limits, and acceptance of nonconforming hardware under the D17.1 contract.