The E7018-1 Designation: What the Suffix Actually Means

Every SMAW electrode carries information encoded in its designation. For the most common structural electrode in North American fab shops—E7018—the base designation tells you tensile strength class (70 ksi minimum), usable positions (all), coating type (low-hydrogen potassium with iron powder), and current polarity (AC or DC+).

The "-1" suffix on E7018-1 adds one more data point: enhanced Charpy V-notch (CVN) impact toughness at a lower test temperature. Both electrodes are classified under AWS A5.1, but they pass different CVN floors when impact testing is performed.

E7018 must demonstrate a minimum absorbed energy at 0°F (–18°C). E7018-1 must meet the same or greater minimum energy at –20°F (–29°C)—a 20-degree colder test temperature. That gap matters in applications where weld metal will be stressed in cold ambient conditions or where fracture toughness is part of the design basis.

From a handling and storage standpoint, both electrodes are low-hydrogen and subject to the same moisture-exposure limits and rebaking requirements under AWS D1.1. The differences only surface in CVN performance and—critically—in how your welding procedure specification accounts for them.

When Does the E7018 vs E7018-1 Distinction Affect Your WPS?

AWS D1.1:2025 Table 6.6 governs essential variables for SMAW and the other common arc processes. A change in filler metal classification that results in a different minimum tensile strength class or different hydrogen designation is an essential variable change requiring a new PQR. But what about E7018 to E7018-1, where the tensile class is identical?

That's where Table 6.8 enters.

Table 6.8 lists the supplementary essential variables that apply only when CVN testing is required by the applicable code, standard, or contract. Rule library based on AWS D1.1:2025; verify against your governing edition (the AHJ or contract may specify 2020 or earlier). Among those supplementary variables is a change in filler metal to one with a different notch-toughness classification.

When CVN supplementary variables apply, E7018 and E7018-1 are not interchangeable. Substituting one for the other is a supplementary essential variable change—you need a new PQR qualified with the electrode you intend to use in production.

When CVN supplementary variables do not apply—when there is no CVN requirement on the WPS or PQR—the "-1" distinction is immaterial to qualification. A WPS qualified with E7018 covers production welding with E7018-1, and the reverse works equally well, because only the base classification and hydrogen level drive essential variable scope under Table 6.6.

See CVN supplementary essential variables and AWS D1.1 Table 6.8 for the complete list of affected variables and how the testing triggers work.

Where CVN Requirements Come From in Structural Work

The most common sources of CVN requirements under AWS D1.1 structural work:

Seismic demand-critical welds. When a project falls under AISC 341 and a connection is designated demand-critical, AISC requires filler metal with documented notch toughness—typically 20 ft-lb at –20°F or better. Most E7018-1 products meet that floor; some manufacturers certify their standard E7018 lots beyond the A5.1 minimum, but relying on that requires mill certification review. The conservative practice is to specify E7018-1 and require lot certifications.

Cold-service structures. Structures in low-temperature environments—refrigerated warehouses, outdoor structures in severe climates, LNG-adjacent applications—often carry owner-specified CVN requirements. Your contract documents or design specification will call these out explicitly.

Owner or EOR supplementary requirements. Some engineering specifications require notch-toughness testing as a matter of policy on all WPS qualifications, regardless of service temperature. When the PQR includes CVN testing for any of these reasons, Table 6.8 is active.

Bridge applications under D1.1. Structural bridge welding typically falls under AWS D1.5, which has its own CVN rules and electrode qualification requirements. If your contract applies D1.1 to a bridge component—unusual but possible—confirm with the owner's engineer which CVN supplementary requirements apply.

Writing the WPS: What to Specify

When CVN supplementary essential variables apply, your WPS must reference the electrode classification precisely—E7018-1, not just E7018. Writing "E7018-H4" is insufficient when the "-1" designation carries a CVN floor that production welds must meet.

Practical guidance for WPS language:

State the A5.1 classification in full. Write "AWS A5.1 E7018-1" or "AWS A5.1 E7018-1-H4" if the low-hydrogen designation is also contractually required. Avoid shorthand like "E7018 or equivalent" when supplementary variables apply—that language invites substitution that is not acceptable.

Link to certified lot testing when required. For demand-critical seismic or owner-specified CVN work, project specifications often require electrode manufacturer certifications showing the actual CVN test results for the lots used in production. Your QC procedure should require lot identification and documentation before electrodes are issued from storage.

Populate the Annex M WPS form correctly. The WPS form under AWS D1.1 Annex M has a filler metal classification field. Use it to specify the full electrode designation and, if your project calls for it, a note that lot-level CVN certifications are required.

For a detailed walkthrough of SMAW WPS parameter ranges and documentation requirements, see SMAW Low-Hydrogen E7018 WPS.

What the PQR Must Document

If CVN supplementary variables apply, the PQR must include Charpy V-notch test results. AWS D1.1 specifies the test specimen location, orientation, and the required minimum absorbed energy. The electrode heat number or lot number used in the test coupon should be recorded—that documents the electrode classification (and, when required, the specific lot) that defines the WPS qualification envelope.

Two common audit findings in this area:

  1. PQR includes CVN test results but the electrode used is documented only as "E7018" without clarifying whether it was E7018-1. When the production WPS specifies E7018-1, this ambiguity can force a PQR retest.

  2. PQR was run with E7018 but the project specification invokes Table 6.8 supplementary variables. The WPS cannot support production use of E7018-1 under the supplementary-essential-variable framework without a new PQR using E7018-1.

See Charpy V-notch testing and Table 6.8 documentation for guidance on test specimen requirements, acceptance values, and how to record CVN data on the PQR report.

Electrode Substitution in Production: The Bottom Line

The practical check for production control is straightforward:

  • CVN testing on the PQR? → Table 6.8 active → E7018 ≠ E7018-1. Do not substitute.
  • No CVN testing on the PQR? → Table 6.8 dormant → E7018 and E7018-1 are interchangeable for WPS coverage purposes.

For any project where cold-service toughness, seismic demand-critical designations, or owner specifications invoke CVN requirements, specify E7018-1 in the WPS, qualify the PQR with E7018-1, and establish a lot-certification workflow in your QC procedure. The cost of getting this wrong is a weld that fails the notch-toughness acceptance requirement—which means a PQR retest or field repair of production welds.

For cold-service structural applications and the broader CVN toughness planning required in your procedure library, see cold-service WPS and CVN toughness requirements.

If you're building or auditing a WPS library and want every procedure correctly qualified for your project mix—including CVN-sensitive and seismic work—see how WPS Welding manages the procedure qualification process →