Are any grades of A913 prequalified under AWS D1.1?

Yes. AWS D1.1 includes A913 Grades 50 and 60 in the prequalified base metal table. Grades 65 and 70 are not prequalified — they require a qualified WPS backed by a PQR before the first production weld can be made.

Why is preheat lower for A913 Grade 65 than for conventional Grade 65 steel?

A913 is produced by quenching-and-self-tempering (QST), which achieves high yield strength through microstructural refinement rather than high alloy additions. The resulting carbon equivalent is lower than a conventionally rolled high-strength steel of the same yield strength, so the minimum preheat requirement is correspondingly lower. Always confirm preheat from the mill test report carbon equivalent, not just the nominal grade.

Can I use a A572 Grade 65 PQR to weld A913 Grade 65?

Generally no. Base metal is an essential variable under AWS D1.1 Table 6.6. A913 Gr. 65 belongs to a different base metal group than A572 Gr. 65. Using a PQR qualified on A572 Gr. 65 to support a WPS on A913 Gr. 65 is a nonconformance unless the base metal grouping table in the code explicitly permits the substitution. Qualify the PQR on representative A913 material.

What is the maximum recommended heat input for welding A913 Grade 65?

A913 producers publish maximum heat input recommendations in their technical data sheets — commonly in the range of 80 to 100 kJ/in, though this varies by grade and producer. The PQR-qualified heat input range should not exceed the steel producer's recommendation. Document the maximum heat input on the WPS and enforce it during production.

WPS and PQR for ASTM A913 high-strength steel columns

ASTM A913 Grades 65 and 70 require procedure qualification beyond the prequalified limits in D1.1. Here's how to build the WPS and PQR for QST steel.

ASTM A913 is the standard for high-strength low-alloy steels produced by the quenching-and-self-tempering (QST) process. It covers wide-flange sections and other structural shapes in Grades 50, 60, 65, and 70. The Grade 65 and 70 are widely used for moment frame columns where architects specify smaller section sizes, and AISC 341 permits A913 Grade 65 for seismic columns under specific conditions without the through-thickness testing required for other high-yield alternatives.

If your shop receives A913 Grade 65 or 70 material, the welding procedure qualification path is different from the prequalified route used for A36 or A992.

Why QST changes the weldability picture

Conventional high-strength steels achieve elevated yield strength through alloying — higher carbon, manganese, and microalloying additions that raise the carbon equivalent and, with it, the required preheat. A572 Grade 65 is a typical example: elevated yield, elevated carbon equivalent, elevated preheat requirement.

A913 takes a different metallurgical path. The section is briefly quenched after rolling and then allowed to self-temper using the residual heat stored in the steel core. The result is a fine-grained, tempered structure with high yield strength but a carbon equivalent closer to what you'd see in a conventional Grade 50. For Grade 65, the carbon equivalent is typically low enough that minimum preheat requirements are comparable to A572 Grade 50, not A572 Grade 65.

The trade-off is that the QST microstructure can be partially degraded by high heat input welding. The fine grain structure that provides strength and toughness is sensitive to excessive heat; prolonged exposure at high temperatures in the HAZ coarsens the grain structure and reduces toughness. Heat input control is not just good welding practice for A913 — it is a structural property preservation requirement.

Prequalified status under AWS D1.1

AWS D1.1 lists A913 Grades 50 and 60 among the prequalified base metals. A913 Grades 65 and 70 are absent from the prequalified table. That omission means a WPS for Grades 65 or 70 must be qualified by a PQR, per the qualification provisions of AWS D1.1 Clause 6.

This is a common error in shops transitioning from lower-strength column schedules to high-seismic or architecturally slender designs. A fabricator who has been welding A913 Grade 50 columns on a prequalified basis will sometimes assume Grade 65 can be handled the same way when the structural engineer revises the column schedule. The switch from Grade 50 to Grade 65 requires new procedure qualification before the first production weld.

Building the PQR for A913 Grade 65 or 70

The PQR follows the standard path under AWS D1.1 Clause 6. The test assembly should use representative material: a heat-certified A913 Grade 65 or 70 section from the same product specification as the production material. Substituting a different base metal for the mockup on the assumption that it is metallurgically equivalent is a nonconformance unless the base metal grouping in the code explicitly permits the substitution.

Essential variables per AWS D1.1:2025 Table 6.6 apply. The most frequently used processes for A913 column welding are SMAW with E8018 or E9018 series electrodes, FCAW-G, and SAW. Filler metal selection targets matching or modest undermatching yield strength. Gross overmatching — using a filler with substantially higher yield than the base metal — can produce a condition in which the base metal yields preferentially and the weld carries higher-than-designed cyclic stress. Matching yield at or near the base metal nominal is typically preferred for column splices and baseplate welds.

Mechanical testing requirements follow the standard groove weld PQR sequence: cross-weld tensile specimens, and face, root, or side bend specimens depending on thickness. If the project invokes seismic requirements under AWS D1.8, CVN testing on weld metal and HAZ is added to the PQR test matrix. Plan the test plate dimensions and specimen locations to accommodate both D1.1 and D1.8 requirements before welding the mockup.

See PQR tensile and bend test requirements and CVN Table 6.8 supplementary essential variables.

Heat input limits and interpass temperature control

The maximum heat input for A913 Grade 65 welding is not stated in AWS D1.1 — it comes from the steel producer's technical documentation. Most major A913 producers publish a recommended maximum heat input in the range of 80 to 100 kJ/in for Grade 65, though the value varies by producer and product form. The WPS must document both the PQR-qualified heat input range and the producer's recommended maximum, and neither should be exceeded in production.

Maximum interpass temperature is equally important. A913 producers typically recommend a maximum interpass temperature of 400°F to 450°F for Grades 65 and 70. This is lower than the 500°F or higher interpass temperatures that might be acceptable for conventional structural steel. On thick multipass column splices or baseplate groove welds, maintaining interpass temperature discipline requires monitoring between passes — not just checking at the start of the weld.

The interpass temperature limit belongs on the WPS, and the inspection plan should include documented interpass temperature readings at representative intervals. See heat input control and documentation on a WPS for guidance on recording and tracking these values.

Reading the mill test report for A913 material

Before writing the WPS, review the mill test report (MTR) for every A913 heat used in the project:

Certification to ASTM A913/A913M and the specific grade (65 or 70)
Chemical analysis including carbon equivalent (CE) — confirm it is within the expected range for QST production
Mechanical test results: yield strength, tensile strength, elongation, and CVN values if ordered
Heat number and product specification for traceability

If the MTR shows an elevated carbon equivalent — possible from a non-standard heat chemistry or a substitution from a different grade — the preheat and heat input requirements on the WPS may need adjustment. Do not assume that all A913 Grade 65 heats are identical. The MTR is the governing document for each heat, and preheat calculations should be based on the actual CE from the MTR, not the nominal grade.

Common errors in A913 procedure qualification

Using the wrong base metal for the PQR mockup. A572 Gr. 65 is not the same base metal group as A913 Gr. 65. A PQR qualified on A572 does not support a WPS on A913 without a specific code provision permitting the substitution. Verify the base metal grouping before planning the mockup.

Applying a prequalified WPS written for A913 Gr. 50. If the only procedure on file for A913 is a prequalified WPS written for Grade 50, it does not extend to Grade 65. Base metal is an essential variable; the grade change triggers requalification.

Ignoring the producer's heat input limit. Qualifying the PQR at a high heat input and then specifying that heat input on the WPS without checking against the A913 producer's recommendation is a structural integrity risk, not just a code compliance risk.

Missing interpass temperature on the WPS. AWS D1.1 requires interpass temperature limits on the WPS when applicable. For A913 Grade 65, the interpass maximum is producer-driven and must appear on the WPS explicitly.

For a full review of essential variables that require requalification, see WPS essential variables vs. nonessential: what triggers requalification and how to qualify a welding procedure under AWS D1.1. To manage multiple qualified procedures — including A913-specific PQRs — in a searchable library with essential variable tracking, see pricing.

Rule library based on AWS D1.1:2025; verify against your governing edition. A913 material-specific heat input and interpass temperature recommendations should be confirmed with the steel producer's technical documentation and the applicable project specification.