Where are CVN specimens taken from the PQR test plate?

AWS D1.1 requires specimens from the weld metal and the heat-affected zone (HAZ). HAZ specimens are typically notched at 1 mm from the fusion line; some specifications require additional sets at 2 mm and 5 mm from the fusion line.

What temperature is used for CVN testing on structural weld PQRs?

The test temperature is set by the Engineer or contract specification, based on the minimum service temperature of the structure. The AWS D1.1 default is 40°F [4°C] for most structural applications unless the governing spec says otherwise.

Does a change in heat input require new CVN testing?

Yes, under Table 6.8. A significant increase in heat input (which raises the peak HAZ temperature and slows cooling, coarsening the grain structure) is a supplementary essential variable that requires requalification when CVN properties are contractually required.

Sep 28, 20267 min read

CVN Impact Test Specimen Location and Orientation for PQR Under AWS D1.1

AWS D1.1 Table 6.8 triggers CVN testing for certain applications. Here's how PQR test plate layout, specimen location, and notch orientation determine whether your procedure qualifies.

PQR AWS D1.1 CVN impact testing Table 6.8 toughness qualification

New to procedures? Start with WPS welding: what a welding procedure specification is, with a filled-in example.

Charpy V-notch (CVN) impact testing is not part of a standard AWS D1.1 PQR. It only enters the qualification picture when the Engineer or Owner invokes supplemental notch toughness requirements—typically for fracture-critical applications, seismic demand-critical welds, cold-service structures, or Owner-specified toughness criteria. When those requirements are in play, AWS D1.1 Table 6.8 activates a separate set of supplementary essential variables, and the PQR test plate must be set up with precise specimen locations and notch orientations to produce valid results.

Getting the test plate layout right before the PQR weld is made—not after—is where most problems get caught or created.

When CVN Testing Applies: The Table 6.8 Trigger

AWS D1.1:2025 Table 6.8 contains the supplementary essential variables for CVN notch toughness qualification. These variables are supplementary in the strictest sense: they are inert for ordinary structural welds, but become binding the moment the contract or Engineer specifies a minimum CVN value.

The phrase used in AWS D1.1:2025 is typically found in the project specification or the Engineer's weld detail notes as something like: "Weld metal CVN: 20 ft·lbf minimum at 40°F" or "Notch toughness testing per AWS D1.1 Table 6.8 required." When that language appears, the PQR must include CVN data, and any future changes to the WPS variables listed in Table 6.8 require new CVN testing to maintain qualification.

For seismic applications, AWS D1.8 (the seismic supplement to D1.1) has its own CVN requirements for demand-critical welds—typically more stringent values at lower temperatures. AWS D1.8 seismic WPS and demand-critical weld requirements covers how D1.8 modifies the standard D1.1 procedure qualification path.

Test Plate Thickness and the Minimum Floor

AWS D1.1:2025 Table 6.8, row 2(a) establishes a minimum base metal thickness for PQR test plates when CVN testing is required. The 2025 edition lowered this floor relative to the 2020 edition: the minimum is now 1/2 in. [12 mm], down from 5/8 in. [16 mm] in 2020. This matters because thinner plates may have been acceptable as test specimens in a 2020-era PQR but the same plate thickness would not support a CVN specimen from the HAZ.

CVN specimens are 10 mm × 10 mm × 55 mm (full-size). Taking a specimen from the HAZ of a test plate requires sufficient through-thickness material to extract the specimen with the notch positioned correctly relative to the fusion line. Below the minimum thickness, there simply isn't enough material for a valid extraction.

For existing PQRs qualified under the 2020 edition with test plate thicknesses between 1/2 in. and 5/8 in., those PQRs are valid under 2025 rules—the change only affects new qualifications. But if you are writing a new PQR referencing 2025, the test plate must meet the new floor.

Specimen Location Requirements

AWS D1.1 requires CVN specimens from two locations in the PQR test plate:

Weld metal specimens are positioned with the long axis of the specimen aligned with the weld axis (longitudinal orientation). The notch is machined perpendicular to the plate surface, located at the centerline of the weld metal section. For multi-pass welds, the weld metal specimen is extracted from the region of the last completed fill passes, not the root. Weld metal CVN values are primarily sensitive to filler metal composition, heat input, and interpass temperature.

HAZ specimens are positioned with the long axis perpendicular to the weld axis (transverse orientation). The notch is positioned relative to the fusion line—AWS D1.1 requires the notch centerline to be placed at approximately 1 mm from the visible fusion line. The fusion line location must be verified by etch after the specimen is machined, and documented in the PQR test report.

Some project specifications (particularly bridge work under AASHTO or Owner-specified fracture control plans) require multiple HAZ specimen sets at:

1 mm from the fusion line (coarse-grain HAZ region)
2 mm from the fusion line
5 mm from the fusion line

When that multi-set requirement is specified, all three sets must pass. The 1 mm set is the most challenging because it samples the coarse-grained HAZ, which has the lowest toughness in the cross-section.

Notch Orientation and Through-Thickness Position

For both weld metal and HAZ specimens, the through-thickness position of the notch matters. AWS D1.1 places the weld metal notch at the mid-thickness of the weld metal, which for a multi-pass weld is usually in the fill passes. The HAZ notch is placed at the quarter-point or mid-thickness of the test plate, depending on the plate thickness and the specification.

The rationale: the surface of the weld and base metal are always cooled by air or backing on both sides, giving slightly better toughness than the center of the plate or weld deposit. The mid-thickness or quarter-point location captures a more representative worst-case value.

When a test plate is thin enough that only a sub-size specimen can be produced (width less than 10 mm), the CVN result must be adjusted by conversion factors per ASTM E23. Most structural specifications require full-size specimens; sub-size is only acceptable if the test report clearly documents the adjustment and the Engineer accepts it.

Test Temperature Selection and Documentation

The CVN test temperature is not set by AWS D1.1 itself—it is set by the Engineer or Owner's specification based on the minimum service temperature of the structure. Common values for structural steel in the United States:

40°F [4°C] — most common for general structural applications in moderate climates
0°F [−18°C] — cold climate structures, northern-tier outdoor applications
−20°F [−29°C] — offshore, cold-service, cryogenic transition zone work
+70°F [+21°C] — when the spec simply requires "room temperature CVN" for comparison

The test temperature must be recorded in the PQR, and the WPS must reference the PQR's qualified temperature. A change to a lower required temperature is a requalification trigger under Table 6.8, because the original PQR data may not predict behavior at the new lower temperature.

Table 6.8 Supplementary Essential Variables

Once CVN testing is in play, any change to these WPS variables requires a new PQR with new CVN testing:

Row 2(a): Decrease in base metal thickness below the minimum (1/2 in. [12 mm] per the 2025 edition). A PQR on 1/2 in. plate does not qualify production welding on 3/8 in. material when CVN is required.

Row 2(b): A change in the P-number or base metal group—each base metal group has distinct HAZ toughness characteristics, and CVN data from one base metal group does not transfer to another.

Row 4: An increase in maximum heat input beyond what was used in the PQR. Heat input directly affects the HAZ grain size and cooling rate, which control toughness in the coarse-grained HAZ. High heat input = coarser grain = reduced toughness. The WPS must cap heat input at or below the PQR value, not merely state a range.

Row 5: A change in PWHT condition (from no PWHT to PWHT, or a change in PWHT temperature or hold time). PWHT alters grain boundary condition and residual stress state in ways that materially affect CVN results.

Row 8 (2025 edition): A change in maximum interpass temperature (increase only). The 2025 edition dropped preheat from this row compared to prior editions—only the maximum interpass temperature increase now triggers requalification, not a preheat change alone. This is a notable change from 2020 that affects shops updating their WPS libraries.

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

Documenting CVN Results on the PQR

The PQR test report for a CVN-required qualification must include:

Specimen ID and extraction location diagram (showing the fusion line, specimen centerline, and notch position)
Specimen dimensions (full-size or sub-size)
Test temperature (calibrated bath temperature, with calibration record reference)
Individual specimen values (not just the average)—AWS D1.1 sets acceptance on individual minimums as well as averages
Fracture appearance (percentage shear fracture)
Lateral expansion value in some specifications
Lab accreditation and test date
CWI or authorized representative review signature

The three-specimen set average must meet the specified minimum, AND no individual specimen can fall below a specified drop-below-average threshold. Both criteria apply; a high-low-high spread that averages to acceptance but has one specimen below the allowable minimum is still a rejection.

Connecting PQR CVN Data to Your WPS

After the PQR is complete and CVN results are documented, the WPS must bound the qualified range:

Maximum heat input ≤ PQR heat input
Interpass temperature ≤ PQR maximum measured interpass temperature
PWHT condition must match (or be established as a separate qualification)
Base metal must be within the qualified P-number group

For shops that maintain a WPS library covering multiple heat input ranges (different thicknesses, joint configurations), each WPS must cross-reference the PQR that supports its CVN coverage. A blanket reference to "PQR-001" without specifying which heat input envelope that PQR qualifies is not a complete reference chain.

If you manage multiple PQRs with overlapping CVN data across different base metals and heat input ranges, a structured WPS library management approach helps maintain the qualification traceability that Owner auditors and third-party QA inspectors look for.

For related qualification topics, see Charpy V-notch CVN testing under AWS D1.1 Table 6.8 and cold-service structural WPS CVN toughness requirements. To manage PQR documentation and track qualification scope across your shop's WPS library, visit WPS Welding.

FAQ

Frequently asked.

When does AWS D1.1 require CVN impact testing on a PQR?: When the Engineer or contract specifies supplemental CVN toughness requirements—typically for fracture-critical members, seismic demand-critical welds, cold service structures, or Owner-mandated toughness applications. Table 6.8 lists the supplementary essential variables that apply when CVN testing has been invoked.
Where are CVN specimens taken from the PQR test plate?: AWS D1.1 requires specimens from the weld metal and the heat-affected zone (HAZ). HAZ specimens are typically notched at 1 mm from the fusion line; some specifications require additional sets at 2 mm and 5 mm from the fusion line.
What temperature is used for CVN testing on structural weld PQRs?: The test temperature is set by the Engineer or contract specification, based on the minimum service temperature of the structure. The AWS D1.1 default is 40°F [4°C] for most structural applications unless the governing spec says otherwise.
Does a change in heat input require new CVN testing?: Yes, under Table 6.8. A significant increase in heat input (which raises the peak HAZ temperature and slows cooling, coarsening the grain structure) is a supplementary essential variable that requires requalification when CVN properties are contractually required.