Can I use an E7018 electrode on dual-certified A36/A572 Gr 50 steel?

Yes, with context. E7018 nominally delivers 70 ksi tensile strength, which meets the matching requirement for A572 Gr 50's 65 ksi minimum Fu. AWS D1.1 matching requirements are based on specified minimums, not mill-test actuals. For demand-critical or seismic welds, check with the EOR.

How should I list dual-certified steel in the WPS base metal field?

Record both certifications: 'ASTM A36 / A572 Gr 50 (dual cert)'. The PQR base metal entry should match whatever specification appeared on the test coupon's MTR. This prevents an audit flag when the next heat of plate arrives showing dual certification.

Does a dual-cert MTR satisfy AWS D1.1:2025 Table 3.1 prequalified base metal requirements?

Yes. Both A36 and A572 Gr 50 appear in AWS D1.1:2025 Table 3.1 as prequalified base metals. A dual-certified plate qualifies under either row and does not require a PQR coupon for a prequalified WPS.

If my WPS lists A36 but the MTR shows dual cert A36/A572 Gr 50, is that a requalification trigger?

For a prequalified WPS, no — both metals are prequalified Table 3.1 materials in the same group. For a PQR-qualified WPS, check AWS D1.1:2025 Table 6.6 Row 1: both A36 and A572 Gr 50 fall in the same base metal group, so the existing PQR covers both. The WPS should still be updated to accurately describe the actual material.

Dual-Certified A36/A572 Gr 50 Steel: WPS Documentation

When your mill cert shows both A36 and A572 Gr 50, here's how to document the base metal on your WPS and avoid the audit flag every inspector looks for.

Walk into any structural fab shop and you'll find a stack of mill certs where the specification field reads: ASTM A36 / ASTM A572 Gr 50. The plate rolled that way because A36's minimum yield (36 ksi) and A572 Grade 50's minimum yield (50 ksi) overlap once you account for typical mill rolling practice — the steel often tests above 50 ksi regardless of the ordering spec, so the producer certifies it to both at no extra cost.

That's fine metallurgically. The documentation problem surfaces when the WPS says "ASTM A36" and the MTR that gets pulled at audit says "A36 / A572 Gr 50 (dual cert)." An alert inspector will flag the discrepancy. Knowing how to handle it in the WPS library before the audit saves rework.

Why dual certification happens

ASTM A36 specifies a minimum Fy of 36 ksi but no maximum. ASTM A572 Grade 50 requires Fy ≥ 50 ksi and Fu ≥ 65 ksi. Modern wide-flange and plate rolling consistently produces steel in the 55–65 ksi actual yield range — well above A36's floor. The mill certifies to both because the same heat passes both specifications' chemistry and tensile requirements simultaneously.

AISC has addressed this in design guidance since the 1990s: if you design a connection assuming Fy = 36 ksi but the plate actually delivers Fy = 55+ ksi, certain connection details — especially in seismic demand-critical applications — may be non-conservative for the actual material. That is an EOR and design concern, not a welding procedure concern per se, but it influences which filler metal you specify.

Recording base metal on the WPS

The WPS base metal field should reflect what the governing contract specifies or, when the contract is silent, what the MTR for that heat of steel shows. Three defensible approaches:

Option A — Record both certifications. ASTM A36 / ASTM A572 Gr 50 (dual cert). This is the most portable entry. Any auditor can match it against an MTR showing either single or dual certification without triggering a discrepancy. For a WPS library covering multiple projects, this entry survives order-to-order variation in how the mill chooses to certify.

Option B — Record the controlling specification. If the contract specifies A572 Gr 50 as the ordering spec (even though the MTR also shows A36), record A572 Gr 50. This is the governing specification for design intent; the A36 certification is incidental. This option is cleaner when all material on the project is ordered as A572 Gr 50 and the dual cert is just a mill practice.

Option C — Record A36 only. Acceptable only when the contract and MTR both reference A36 as the sole specification. If the MTR also shows A572 Gr 50, this entry will look incomplete to a thorough inspector and should be updated.

Prequalified status under AWS D1.1:2025

Both ASTM A36 and ASTM A572 Grade 50 appear in Table 3.1 of AWS D1.1:2025 as prequalified base metals. A dual-certified plate satisfies the prequalified requirement under either row. No PQR coupon is required to use dual-certified plate on a prequalified WPS — the plate is Table 3.1 material regardless of which certification the mill chose to include.

See prequalified base metals under AWS D1.1 for the full list and the carbon-equivalent preheat implications that change between A36 and higher-alloy heats of A572.

Filler metal matching for dual-certified steel

E7018 electrodes nominally deliver 70 ksi minimum tensile strength. ASTM A572 Grade 50 specifies Fu ≥ 65 ksi minimum, so E7018 is a matching filler for A572 Gr 50 by AWS D1.1 criteria. Against actual plate that tests at Fu = 80–90 ksi on the MTR, the electrode is technically undermatching against actual properties — but AWS D1.1 matching requirements are based on specified minimum tensile strength, not mill-test actuals. E7018 satisfies the matching requirement.

The exception: seismic demand-critical welds under AWS D1.8 apply more stringent criteria, including Fy/Fu ratio requirements and CVN testing of the filler metal lot. See CVN filler metal selection for demand-critical welds for that scenario.

MTR review for dual-certified plate

When reviewing the mill test report during incoming material verification, check these items specifically for dual-certified heats:

Specification field — note whether the MTR shows one standard or two. Record it before filing.
Carbon equivalent — A572 Gr 50 permits higher alloy content than A36. Higher CE means higher preheat requirements under AWS D1.1 Appendix I. If your WPS preheat was calculated for A36-chemistry steel, verify that a dual-cert heat within A572's chemistry envelope still falls within your WPS preheat assumptions.
Actual yield vs. design basis — for demand-critical or moment-frame connections, flag actual Fy to the EOR if it exceeds the design basis by a significant margin.
Heat/lot number — record it against the weld map. AWS D1.1 traceability requirements for quality-sensitive applications expect heat-level traceability from MTR through weld record.

Essential variable implications for PQR-qualified WPS

If your WPS is qualified by test (rather than prequalified), base metal specification is an essential variable under AWS D1.1:2025 Table 6.6, Row 1, which addresses changes in base metal specification group. Both A36 and A572 Gr 50 fall in the same group under the AWS D1.1:2025 base metal groupings in Table 6.9. A single PQR coupon cut from either specification qualifies procedures for both within that group.

This means no new PQR test is required simply because the production order switched from A36-only plate to a dual-certified A36/A572 Gr 50 heat. Update the WPS base metal field to reflect the broader coverage, re-issue the document with the new revision level, and file it. The underlying qualification data remains valid.

If the shop later needs to weld to A514 or A709 HPS 100W — different groups — a separate PQR coupon is required regardless of the dual-cert situation on the lower-strength steels. See AWS D1.1 Table 6.9 base metal groups for the full group mapping.

Rule library based on AWS D1.1:2025; verify against your governing edition.

Practical recommendation

On new WPS documents covering common structural carbon steels, write the base metal as ASTM A36 / A572 Gr 50 (dual cert acceptable) and add a brief note in the remarks field: "Mill test reports showing dual ASTM A36 / A572 Gr 50 certification are acceptable for this WPS." That single line closes the audit question before it opens.

Then audit your existing WPS library for A36-only entries. For any procedure where you regularly receive dual-certified plate, expand the base metal field to reflect that reality. The change is a documentation revision, not a requalification event, and it eliminates a recurring source of hold-point delays during third-party inspection.

For a WPS library that stores MTR links against each procedure and flags when incoming base metal certification doesn't match the WPS base metal field, see what the qualification management tools cover.