AWS A5.x Filler Metal Classification — Electrode & Wire Designations
The AWS A5.x series defines welding consumable classifications for every arc welding process. Each specification assigns designations based on tensile strength, position capability, coating type, and shielding gas. D1.1:2025 Table 5.7 references A5.x classifications for filler metal matching to base metal groups.
How Electrode Designations Work
Every AWS filler metal designation encodes essential information about the consumable in a structured alphanumeric string. The designation tells the welder and engineer exactly what the electrode or wire is designed to do. Understanding this system is fundamental to writing a correct WPS and selecting the right consumable for the joint.
Take the most common structural welding electrode, E7018, as an example. Each character in the designation carries specific meaning:
The E prefix indicates an electrode consumable. The next two digits (70) represent the minimum tensile strength in ksi (70 ksi = 480 MPa). The third digit (1) indicates position capability: 1 means all positions (flat, horizontal, vertical, overhead), while 2 means flat and horizontal only. The fourth digit (8) designates the coating type and current characteristics — in this case, an iron-powder low-hydrogen coating designed for AC or DC+ operation.
For GMAW/GTAW wire, the prefix changes to ER (electrode-rod), and the designation follows a different pattern. ER70S-6 breaks down as: ER = electrode/rod, 70 = 70 ksi tensile, S = solid wire, 6 = deoxidizer chemistry. For flux-cored wire, E71T-1 uses: E = electrode, 7 = 70 ksi, 1 = all-position, T = tubular (flux-cored), 1 = gas-shielded usability designator.
Key A5.x Specifications
AWS publishes separate A5.x specifications for each combination of base metal type and welding process. The table below covers the specifications most commonly referenced in structural steel fabrication under D1.1.
| Spec | Scope | Common Classifications | Process | Current Edition |
|---|---|---|---|---|
| A5.1 | Carbon steel SMAW | E6010, E6011, E6013, E7014, E7018, E7024 | SMAW | A5.1:2025 |
| A5.5 | Low-alloy SMAW | E7018-A1, E8018-C3, E9018-G | SMAW | A5.5:2014 |
| A5.18 | Carbon steel GMAW/GTAW | ER70S-3, ER70S-6 | GMAW, GTAW | A5.18:2023 |
| A5.20 | Carbon steel FCAW | E71T-1, E71T-8, E71T-11 | FCAW | A5.20:2005 (superseded by A5.36 for new work) |
| A5.28 | Low-alloy GMAW/GTAW | ER80S-D2, ER90S-G | GMAW, GTAW | A5.28:2020 |
| A5.36 | Unified FCAW/MCAW | E71T1-C1A2-CS1 | FCAW, MCAW | A5.36:2016 |
| A5.9 | Stainless steel | ER308L, ER309L, ER316L | GMAW, GTAW, SAW | A5.9:2022 |
Classifications shown are designation names which are unchanged across editions; mechanical property requirements and testing methods may differ between editions. Always reference the edition specified in your contract documents.
The A5.36 Unified Designation System
AWS A5.36 represents a fundamental shift in how flux-cored and metal-cored electrodes are classified. Before A5.36, carbon steel FCAW electrodes fell under A5.20 and low-alloy FCAW electrodes under A5.29. These two specifications used different designation systems, making cross-referencing difficult and limiting the information encoded in the designation itself.
A5.36 replaces both with a single unified system that encodes significantly more information in each designation string. The designation E71T1-C1A2-CS1 breaks down as follows:
The shielding gas designator (C = CO2, M = mixed gas) tells the user exactly which gas the electrode was tested and classified with. The impact class (A = no impact requirement, A2 = −20°F impact) and chemistry suffix (CS = carbon steel, NI = nickel alloy) provide information that required looking up supplement tables under the old A5.20 system.
Existing A5.20 and A5.29 designations remain valid for electrodes already classified under those specifications. However, new electrode development and new classifications use the A5.36 system. When writing a WPS, you may reference either the legacy A5.20 designation or the equivalent A5.36 designation — both are accepted under D1.1.
Filler Metal on a D1.1 WPS
The filler metal classification is one of the most important entries on a welding procedure specification. Under D1.1, filler metal selection is governed by Table 5.7, which maps base metal groups to compatible filler metal groups. The filler metal must provide matching or overmatching strength to the base metal being joined.
For prequalified WPSs (Clause 5), the filler metal must be listed in Table 5.7 for the applicable base metal group. Using a filler metal outside of Table 5.7 requires WPS qualification by test under Clause 6. The WPS form requires three filler metal entries: the A5.x specification number (e.g., A5.18), the electrode classification (e.g., ER70S-6), and the manufacturer trade name or brand.
Filler metal is an essential variable under both Table 5.5 (prequalified WPS essential variables) and Table 6.6 (qualified WPS essential variables). A change in filler metal classification — for example, switching from ER70S-6 to ER70S-3 — requires a new or revised WPS. A change in A5.x specification (e.g., from A5.18 to A5.28) always requires a new procedure.
The filler metal classification also determines the preheat category under Table 5.11. Low-hydrogen electrodes (E7018, E71T-1, ER70S-6) fall under Category B, which requires lower preheat temperatures. Non-low-hydrogen electrodes (E6013, E71T-11) fall under Category A, which requires higher preheat. This distinction directly affects fabrication cost and schedule, making the filler metal selection a critical early decision in WPS development.
Frequently Asked Questions
E7018 is classified under AWS A5.1. The E designates an electrode. 70 indicates 70 ksi (480 MPa) minimum tensile strength. 1 indicates all-position capability (flat, horizontal, vertical, overhead). 8 designates an iron-powder low-hydrogen coating. The low-hydrogen coating is the reason E7018 falls under D1.1 Table 5.11 Category B for preheat, requiring lower preheat temperatures than non-low-hydrogen electrodes like E6013.
Both are FCAW electrodes classified under A5.20, but they use different shielding methods. E71T-1 is gas-shielded (FCAW-G) and requires external CO2 or Ar/CO2 shielding gas. E71T-11 is self-shielded (FCAW-S) and requires no external gas. E71T-1 produces cleaner weld metal with lower hydrogen and is preferred for shop fabrication. E71T-11 is preferred for field erection where wind makes gas shielding impractical. Under D1.1 Table 5.11, E71T-1 falls under Category B (low hydrogen). E71T-11 falls under Category A (non-low-hydrogen).
AWS A5.36 provides a unified designation system for flux-cored and metal-cored electrodes that replaces the separate A5.20 (carbon steel FCAW) and A5.29 (low-alloy FCAW) specifications. The A5.36 designation encodes more information: electrode type, strength, position, shielding gas, impact class, and chemistry in a single designation string. Existing A5.20 and A5.29 designations remain valid, but new electrode development uses the A5.36 system.
Reference the AWS A5.x specification and classification that matches your consumable. Table 5.7 in D1.1 lists the filler metal groups that provide matching strength for each base metal group. For prequalified WPSs, the filler metal must be listed in Table 5.7 for the applicable base metal group. The WPS must state the specification (e.g., A5.18), the classification (e.g., ER70S-6), and the manufacturer trade name.