Where are Charpy V-notch specimens located in an AWS D1.1 PQR test plate?

CVN specimens are taken from the heat-affected zone (HAZ) and weld metal of the PQR test coupon. The specific location — notch at the fusion line, 1 mm from fusion line, or through weld metal — depends on what the governing specification or contract requires for the application.

How many Charpy specimens are required per PQR test plate under AWS D1.1?

AWS D1.1 does not prescribe a fixed Charpy specimen count for standard WPS qualification. When CVN testing is required by contract or engineering specification, the test plan specifies the quantity and locations. Three specimens per location (weld metal and HAZ) is a common minimum.

What AWS D1.1 table controls CVN supplementary essential variables?

AWS D1.1:2025 Table 6.8 lists the supplementary essential variables applicable when Charpy V-notch testing is required. Changes to parameters in Table 6.8 — such as an increase in heat input beyond the qualified maximum or a decrease in preheat — require requalification when CVN requirements are invoked.

Does cold-service structural steel always require Charpy testing in the PQR?

Not by default. AWS D1.1 does not mandate CVN testing for all WPS qualifications. CVN becomes a required qualification test when the contract documents, the EOR's specification, or the governing structural code (e.g., AISC 341 for seismic demand-critical welds) invoke CVN requirements.

CVN Specimen Location and Orientation in PQR Test Plates

Where Charpy V-notch specimens are cut from the PQR test plate, how many are required, and how results govern AWS D1.1 Table 6.8 supplementary essential variable coverage.

When Charpy Testing Enters the WPS Qualification

Standard AWS D1.1 WPS qualification under Clause 6 requires tensile and guided-bend tests. Charpy V-notch (CVN) impact testing is not part of the base qualification for most structural applications — it enters the PQR only when the contract documents, the engineer of record's specification, or a referenced design standard explicitly requires toughness qualification.

The applications that commonly trigger CVN PQR testing in structural steel work:

Cold-service structures (minimum service temperature below 32°F / 0°C)
Seismic demand-critical welds per AISC 341 / AWS D1.8
Fracture-critical member connections under owner or AISC specification
Bridges designed to AWS D1.5 (which has its own CVN requirements)

When CVN is invoked, the PQR test plate must produce Charpy specimens at specified locations, at a specified test temperature, meeting minimum absorbed energy and lateral expansion requirements. Critically, once CVN qualification is part of the PQR, the supplementary essential variables in AWS D1.1:2025 Table 6.8 become binding — changes to those variables require requalification whether or not the base essential variables in Table 6.6 are affected.

Rule library based on AWS D1.1:2025; verify against your governing edition (the AHJ or contract may specify 2020 or earlier).

PQR Test Plate Layout for CVN Specimens

The PQR test coupon for groove welds is a multi-pass weld plate that serves as the source for all mechanical test specimens. When CVN is required, the test plan allocates locations in the coupon for impact specimens in addition to the standard tensile and bend specimens.

Charpy V-notch specimens (ASTM A370, 10mm × 10mm standard size or sub-size) are machined perpendicular to the weld, with the notch oriented to sample either:

Weld metal — notch located within the deposited weld metal, away from the fusion line
Heat-affected zone (HAZ) — notch located at the fusion line, 1 mm from fusion line, 2 mm from fusion line, or 5 mm from fusion line, as specified

The distinction matters because weld metal CVN performance and HAZ CVN performance can differ substantially for the same procedure. High-heat-input SAW procedures that produce excellent weld metal toughness can produce coarse-grained HAZ regions with significantly lower impact energy. The test plan must specify which locations are tested for the application.

For seismic demand-critical welds per AISC 341, CVN requirements typically apply to the weld metal specifically, reflecting the fracture mechanics of cyclically loaded connections. The specification for those applications sets both the notch location and the minimum energy at the specified test temperature.

How Many Specimens and Where

AWS D1.1 itself does not prescribe a specific Charpy specimen count per PQR. When CVN is required, the test plan is either:

Specified by the contract documents or project specification
Derived from AISC 341 Appendix W requirements for seismic procedures
Set by the testing laboratory in consultation with the EOR based on the application

A commonly used test matrix for structural cold-service PQR qualification:

Three specimens — weld metal centerline
Three specimens — fusion line (HAZ)
Three specimens — 1 mm from fusion line (HAZ, CGHAZ if thermally severe)

The three-specimen set at each location provides a set average. Single-specimen outliers that fall below the specified minimum are evaluated against the set: typically, no more than one specimen may fall below the minimum, and no specimen may fall below 2/3 of the minimum, for the set to pass. The governing specification defines the acceptance criterion; the test plan should reference it explicitly rather than leaving it to the lab's interpretation.

Specimen thickness: when plate thickness is insufficient for a full 10mm × 10mm Charpy bar (generally plates thinner than 11 mm), sub-size specimens (7.5 mm × 10 mm, 5 mm × 10 mm) are permissible per ASTM A370 with adjusted acceptance criteria. The PQR must record the specimen dimensions so the qualification coverage can be correctly evaluated.

Test Temperature and Shift

CVN specimens are tested at the temperature specified by the contract or design standard, not at room temperature. The test temperature should reflect the minimum anticipated service temperature for the structure, sometimes adjusted by a ductile-to-brittle transition margin.

AWS D1.5 (bridge welding) has explicit CVN temperature and energy requirements. AISC 341 and AWS D1.8 specify 70°F (21°C) test temperature for demand-critical weld metal CVN as a standard baseline, with the assumption that structural steel fabrication in the US does not typically expose moment frame joints to temperatures below 0°F in service.

For cold-service structures — unheated tanks, offshore platforms in northern climates, arctic exposure — the test temperature may be -40°F (-40°C) or lower. The cryogenic test procedure is conducted per ASTM A370 with specimens submerged in a refrigerated bath and transferred to the anvil within a specified time window. Lab capability to conduct cryogenic Charpy testing is a real constraint: not all accredited labs are equipped for sub-zero work, which affects PQR test laboratory selection.

Table 6.8: What Changes Once CVN Is Qualified

Once CVN toughness testing is part of the PQR, AWS D1.1:2025 Table 6.8 applies. These supplementary essential variables must be held within their qualified limits or requalification is required. The key variables include:

Heat input (increase): Any increase in heat input beyond the maximum qualified in the CVN PQR requires requalification. Higher heat input coarsens the HAZ grain structure, reducing impact toughness. A procedure qualified at 55 kJ/in maximum cannot be run at 70 kJ/in on a CVN-required joint without new testing.
Filler metal strength level (decrease): Downgrading to a lower-strength filler requires requalification when CVN applies. The CVN performance of the weld metal is classification-specific.
Preheat (increase — interpass temperature maximum increase): Under the 2025 edition, Table 6.8 row 8 specifically addresses interpass temperature maximum increases as a supplementary essential. An increase in the maximum interpass temperature above the qualified value triggers requalification when CVN is invoked.
Base metal group: Change in base metal group requires requalification, as the HAZ response differs by chemistry and heat treatment condition.

Note that AWS D1.1:2025 Table 6.8 dropped preheat decreases from its scope compared to earlier editions — only interpass temperature maximum increases now trigger CVN requalification. This was a deliberate 2025 content change; if your WPS library was built under the 2020 edition, verify the Table 6.8 requirements against the current text.

See CVN supplementary essential variables under AWS D1.1 Table 6.8 for the full breakdown of Table 6.8 by row.

Recording CVN Results on the PQR

The PQR test report must record CVN results in a format that communicates specimen identity, location, test temperature, absorbed energy (ft-lbf or J), and lateral expansion (mils or mm). ASTM A370 test certificates provide this data; the lab report must be attached to the PQR as a supporting document rather than summarized in the PQR body alone.

The PQR narrative should identify:

Which locations were tested (weld metal, fusion line, 1 mm HAZ, etc.)
The test temperature
Individual specimen values and set average
The acceptance criterion and whether the set passed or failed

A PQR that records only "CVN results: acceptable" without specimen-level data is deficient. An AISC auditor or EOR reviewer will request the underlying lab report; if it is not on file, the qualification may be treated as incomplete. See how to read a PQR test report for the standard review checklist that covers CVN documentation.

Impact on WPS Heat Input Documentation

The most practical consequence of CVN qualification for production welding is the heat input ceiling. Once Table 6.8 is binding, every production pass on a CVN-required joint must stay within the maximum heat input qualified in the PQR. The WPS must document the heat input range, and the CWI must verify that production parameters fall within it.

Heat input in kJ/in is calculated from arc voltage, amperage, and travel speed: (amps × volts × 60) / (travel speed in in/min × 1000). On FCAW and GMAW operations, deposition rate and wire feed speed factor into travel speed calibration.

Production parameter logs for CVN-required joints should record the three inputs (A, V, IPM) for each pass, not just a pass/fail visual check. These records become part of the audit packet for the weld joint.

For cold-service structural WPS and CVN toughness qualification, the full workflow — from PQR design through production parameter control — follows the framework described here, scaled to the specific design temperature and filler metal requirements.

Managing CVN-required WPS alongside standard procedures, and tracking which joints require Table 6.8 compliance, is exactly the kind of cross-procedure documentation problem that a structured WPS library solves. See wpswelding.com/pricing for tools built for QC managers who maintain qualification records across multiple procedures and CVN-sensitive applications.