4.2 PQR Mechanical Test Types: Tension, Guided Bend & Macroetch
Key Takeaways
- Reduced-section tension specimens must achieve a tensile strength not less than the specified minimum tensile strength of the base metal.
- Under the 'Base Metal Break 95% Rule' (Clause 6.10.3.5), if a tension specimen fractures in the base metal outside the weld/fusion line, the test is acceptable if the ultimate strength is not less than 95% of the specified minimum tensile strength.
- Guided bend acceptance criteria allow no individual discontinuity exceeding 1/8 in. (3 mm), a cumulative maximum of 3/8 in. (10 mm) for indications between 1/32 in. and 1/8 in., and corner cracks up to 1/4 in. (6 mm) unless originating from inclusions.
- Macroetch specimens must be polished to at least 600 grit, etched with nital or ammonium persulfate, and visually examined for sound fusion, root penetration, and freedom from cracks.
- Charpy V-Notch (CVN) impact testing evaluates notch toughness at specified design temperatures, requiring a 3-specimen average that satisfies contract fracture-critical requirements.
Last updated: August 2026
Reduced-Section Tension Testing & Acceptance Criteria (Clause 6.10.3.5)
The reduced-section tension test determines the ultimate tensile strength of the welded joint under uniaxial tensile loading. Test specimens are machined to the geometry detailed in Figure 6.10.
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| FIGURE 6.10: REDUCED-SECTION TENSION SPECIMEN |
+-----------------------------------------------------------------------------------------+
| |
| |<--- Grip Area --->| |<-- Reduced Section -->| |<--- Grip Area --->| |
| +-------------------+ +-----------------------+ +-------------------+ |
| | \ / \ / | |
| | \ / ================= \ / | |
| | +-+ | WELD SEAM | +-+ | |
| | Width = W_grip | | | (Flush Ground| | | Width = W_grip | |
| | +-+ ================= +-+ | |
| | / \ / \ | |
| | / \ / \ | |
| +-------------------+ +-----------------------+ +-------------------+ |
| |<-- Width: W_reduced ->| |
| |<--- Length: Min. 2-1/4 in. (60 mm) ------------->| |
| |
+-----------------------------------------------------------------------------------------+
Specimen Preparation & Geometry
- Weld Reinforcement: The face reinforcement and backing strip / root reinforcement must be machined or ground flush with the base metal surface (±0.010 in. [0.25 mm]).
- Reduced Section Width (W): Typically 0.750 in. (19 mm) for plate thickness T > 3/8 in., or 1.500 in. (38 mm) for T ≤ 3/8 in.
- Cross-Sectional Area (A): Calculated prior to testing by measuring the exact thickness (T) and reduced width (W) with a calibrated micrometer: A = W × T.
Tensile Strength Calculation Formula
σ_uts = P_max / A = P_max / (W × T)
Where:
- σ_uts = Ultimate tensile strength (psi or MPa)
- P_max = Maximum tensile load recorded at fracture (lbf or N)
- A = Measured cross-sectional area of reduced section (sq. in. or mm²)
Acceptance Criteria (Clause 6.10.3.5)
- Weld Metal / Fusion Zone Fracture: If the specimen fractures in the weld metal or fusion line, the tensile strength σ_uts must equal or exceed the specified minimum tensile strength of the base metal classification (the applicable ASTM specification).
- The "Base Metal Break 95% Rule": If the specimen fractures in the base metal outside of the weld or fusion line, the test shall be accepted provided the calculated tensile strength is not less than 95% of the specified minimum tensile strength of the base metal.
- Dissimilar Strength Steels: If two base metals of different minimum tensile strengths are joined, the calculated tensile strength must meet or exceed the specified minimum tensile strength of the weaker base metal (or 95% if fracture occurs in the weaker base metal outside the weld).
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| WORKED TENSILE TEST EVALUATION EXAMPLE |
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| |
| Base Metal: ASTM A572 Grade 50 (Specified Min. Tensile Strength Fu = 65.0 ksi) |
| Specimen Dimensions: Width W = 0.752 in., Thickness T = 0.998 in. |
| Calculated Area: A = 0.752 in. * 0.998 in. = 0.7505 sq. in. |
| |
| TEST SPECIMEN 1: |
| * Peak Load: P_max = 51,200 lbf |
| * Calculated Tensile Strength: sigma = 51,200 / 0.7505 = 68,221 psi = 68.2 ksi |
| * Fracture Location: Weld Metal |
| * Evaluation: 68.2 ksi >= 65.0 ksi (Specified Minimum) ----------> PASS |
| |
| TEST SPECIMEN 2: |
| * Peak Load: P_max = 47,100 lbf |
| * Calculated Tensile Strength: sigma = 47,100 / 0.7505 = 62,758 psi = 62.8 ksi |
| * Fracture Location: Base Metal (1.5 in. outside weld) |
| * 95% Threshold: 0.95 * 65.0 ksi = 61.75 ksi |
| * Evaluation: 62.8 ksi >= 61.75 ksi (Base Metal Break >= 95%) ----> PASS |
| |
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Guided Bend Tests: Mechanics, Jigs & Acceptance Criteria (Clause 6.10.3)
Guided bend tests evaluate the ductility and internal soundness of the welded joint by subjecting the outer fibers of the specimen to severe tensile strain around a standardized mandrel/plunger.
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| GUIDED BEND SPECIMEN ORIENTATIONS |
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| |
| 1. TRANSVERSE SIDE BEND 2. TRANSVERSE ROOT BEND |
| Specimen thickness = 3/8 in. (10 mm) Root of weld is on the convex (outer) |
| Full weld cross-section strained tension surface during bending |
| +------------------------------+ +------------------------------+ |
| | Base | Weld Metal | Base | | Base | Weld Metal | Base | |
| +------------------------------+ +------------------------------+ |
| ^ Full plate thickness (T) ^ ^ Weld Root on Outside Face ^ |
| |
| 3. TRANSVERSE FACE BEND 4. LONGITUDINAL BEND |
| Face of weld is on the convex Weld seam runs along the specimen length; |
| (outer) tension surface used for dissimilar strength metals |
| +------------------------------+ +==============================+ |
| | Base | Weld Metal | Base | | WELD SEAM | |
| +------------------------------+ +==============================+ |
| ^ Weld Face on Outside Face ^ |
| |
+-----------------------------------------------------------------------------------------+
Guided Bend Testing Fixtures & Dimensions (Figures 6.11 through 6.13)
AWS D1.1 recognizes three approved bend testing fixtures:
- Plunger-Type Guided Bend Jig: Plunger pushes specimen into a U-shaped die.
- Roller-Guided Bend Jig: Specimen bent around a central mandrel using supporting rollers.
- Wrap-Around Guided Bend Jig: Specimen clamped at one end and wrapped around a central mandrel with a rotating roller (recommended to prevent slippage on high-strength alloys).
| Base Metal Group / Yield Strength (Fy) | Plunger / Mandrel Radius (A) | Die Opening (B) | Plunger Width (C) |
|---|---|---|---|
| Fy ≤ 50 ksi (345 MPa) (Groups I & II: A36, A992) | 2t = 0.75 in. (19 mm) | 1.50 in. (38 mm) | 4t + 1/16 in. = 1.56 in. |
| 50 < Fy ≤ 90 ksi (Group III: A572 Gr 65) | 2.5t = 0.94 in. (24 mm) | 1.88 in. (48 mm) | 5t + 1/16 in. = 1.94 in. |
| Fy > 90 ksi (Group IV: A514 / A517 / A709 Gr 100) | 3t = 1.12 in. (28 mm) | 2.25 in. (57 mm) | 6t + 1/16 in. = 2.31 in. |
(Note: t is the nominal specimen thickness, standard 3/8 in. [10 mm]).
Codified Bend Test Acceptance Criteria (Clause 6.10.3.3)
After bending through 180°, the convex (stretched) surface of the specimen is examined for cracks and open discontinuities:
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| CLAUSE 6.10.3.3 BEND TEST ACCEPTANCE RULES |
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| |
| [CRITERION 1: MAXIMUM INDIVIDUAL DISCONTINUITY] |
| * No single crack or open discontinuity shall exceed 1/8 in. (3 mm) in any direction. |
| |
| [CRITERION 2: CUMULATIVE SUM OF DISCONTINUITIES] |
| * The sum of the greatest dimensions of all discontinuities > 1/32 in. (1 mm) |
| and <= 1/8 in. (3 mm) shall not exceed 3/8 in. (10 mm) total. |
| * Discontinuities <= 1/32 in. (1 mm) are IGNORED and not summed. |
| |
| [CRITERION 3: CORNER CRACK EXEMPTION] |
| * Cracks occurring at the rounded corners of the specimen during bending are EXEMPT |
| up to a maximum length of 1/4 in. (6 mm), UNLESS there is clear evidence that they |
| originated from internal slag inclusions, incomplete fusion, or internal defects. |
| |
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Macroetch Examination and Charpy V-Notch (CVN) Testing (Clause 6.10.4 & Clause 6 Part D)
Macroetch Examination Protocol (Clause 6.10.4)
Macroetch examination is mandatory for PJP groove welds (Figure 6.15), fillet weld soundness tests (Figure 6.16), and specialized WPS qualifications.
- Preparation: Transverse cross-sections of the weldment must be saw cut, smoothed, and ground/polished to a surface finish of at least 600 grit.
- Etching Reagents: Etched with a chemical solution to clearly delineate weld metal, heat-affected zone (HAZ), and unaffected base metal. Standard approved reagents include:
- Nital: 5% to 10% Nitric acid in ethanol or methanol.
- Ammonium Persulfate: 10% ammonium persulfate in distilled water.
- Acceptance Criteria:
- The cross-section must exhibit sound weld metal and complete fusion to the root and sidewalls.
- Freedom from cracks, incomplete penetration (beyond PJP design limits), and severe internal porosity or slag.
- For PJP groove welds, the actual effective weld throat (E) must meet or exceed the engineered design value.
Charpy V-Notch (CVN) Impact Testing (Clause 6.26 through 6.29 / Table 6.8)
CVN testing evaluates the resistance of the welded joint to brittle fracture under dynamic shock loading at low operating temperatures.
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| CHARPY V-NOTCH (CVN) SPECIMEN & NOTCH LOCATIONS |
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| |
| |<------------------------- Length: 55 mm ------------------------->| |
| +-----------------------------------+-------------------------------+ ^ |
| | | 45 deg Notch | | |
| | V (2 mm deep, 0.25 mm radius) | 10 mm |
| | + | | |
| | / \ | v |
| +---------------------------------+---+-----------------------------+ |
| |<------------------------ Thickness: 10 mm ----------------------->| |
| |
| NOTCH EXTRACTION LOCATIONS: |
| 1. Weld Metal Centerline (WMC) |
| 2. Fusion Line (FL) |
| 3. Heat-Affected Zone (HAZ): FL + 1 mm, FL + 5 mm |
| |
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- When Required: Only when explicitly specified in contract documents, structural project specifications, or seismic fracture-critical provisions (AWS D1.8).
- Specimen Quantity & Acceptance: A standard test set consists of five specimens (or three specimens if specified), with three broken at the test temperature. The average absorbed energy (ft-lbs or Joules) must meet or exceed the contract value (e.g., 20 ft-lbf [27 J] at 0°F [-18°C]), and not more than one specimen may fall below the required average, with no specimen below the individual minimum (e.g., 15 ft-lbf).
Test Your Knowledge
A reduced-section tension test is performed on an ASTM A36 base metal coupon (specified minimum tensile strength = 58.0 ksi). The specimen has a measured width of 1.500 in. and thickness of 0.375 in. During the test, the specimen fractures in the base metal 2 inches outside the weld zone at a peak tensile load of 31,500 lbf. How should the inspector evaluate this test result per AWS D1.1 Clause 6.10.3.5?
A
B
C
D
Test Your Knowledge
During visual examination of a transverse side bend test specimen following a 180° bend, the inspector observes three discontinuities in the weld metal: one measuring 1/16 in. (1.6 mm), one measuring 3/32 in. (2.4 mm), and one measuring 1/64 in. (0.4 mm). There is also a 3/16 in. (4.8 mm) crack on one corner that shows no evidence of internal slag inclusions. What is the status of this bend specimen per AWS D1.1 Clause 6.10.3.3?
A
B
C
D
Test Your Knowledge
What surface preparation finish and chemical etching reagents are specified for PQR macroetch examination specimens under AWS D1.1 Clause 6.10.4?
A
B
C
D