Welding Consumable Nomenclature: Everything You Need to Know
Welding consumable nomenclature is the standardised coding system that encodes the mechanical properties, chemical composition, positional capability, coating type, and hydrogen control of every electrode, filler wire, and flux used in arc welding. Governed by standards such as AWS A5, ASME SFA, ISO 2560, ISO 14343, and EN 499, these designations allow fabricators, welding engineers, and inspectors to select the correct consumable for a given base material, service condition, and code requirement — without relying on brand names or marketing claims.
Whether you are reading an approved Material Test Report, preparing a Welding Procedure Specification (WPS) that references F-Numbers and A-Numbers, or simply specifying consumables on a purchase order, understanding what each character in a designation like E7018-H4R, ER70S-6, E71T-1M, or F7A2-EM12K actually means is an essential engineering skill. This article breaks down each classification system process by process, with worked decode examples, comparison tables, and practical guidance on hydrogen control and standard cross-referencing.
Coverage includes: SMAW (AWS A5.1 / A5.5), GMAW and GTAW solid wire (AWS A5.18), FCAW (AWS A5.20), SAW flux-wire combinations (AWS A5.17), and the parallel European and ISO classification schemes for each process. Stainless steel and low-alloy consumable families are also addressed.
Why Consumable Nomenclature Matters
Selecting the wrong consumable is one of the most common and consequential errors in fabrication. A low-hydrogen electrode used without proper oven conditioning, an over-alloyed stainless filler applied to a carbon steel joint, or a flux-cored wire run on the wrong shielding gas — each can produce welds with inadequate toughness, hot cracking susceptibility, or premature corrosion failure. The consumable code is the first line of defence against these errors.
Understanding and applying correct nomenclature helps you to:
- Match the consumable mechanical properties to the base material and design stress requirements.
- Achieve code compliance under ASME, API, or AWS D1.1 by correctly identifying the F-Number and A-Number for WPS/PQR qualification.
- Avoid defects such as hydrogen-induced cold cracking, porosity from gas incompatibility, and hot cracking from compositional mismatch.
- Establish reliable traceability and inventory control across suppliers and projects.
- Cross-reference between AWS, ISO, and EN classification systems when substituting imported consumables.
SMAW Electrode Nomenclature — AWS A5.1 and A5.5
Shielded Metal Arc Welding (SMAW) uses covered electrodes whose designation under AWS A5.1 (carbon steel) or AWS A5.5 (low-alloy steel) encodes the key performance characteristics in a compact alphanumeric string. The standard four- or five-digit format is: E XXXX (suffix).
Position Digit — Third Character
| Digit | Permitted Positions | Typical Application |
|---|---|---|
| 1 | All positions — flat, horizontal, vertical, overhead | General fabrication, field welding |
| 2 | Flat and horizontal fillet only | High-deposition flat work |
| 3 | Flat position only (horizontal fillet for some types) | Semi-automatic downhand production |
| 4 | All positions — specifically includes vertical-down | Root pass, pipe welding |
Coating / Current Digit — Fourth Character
| Digit | Coating Type | Current | Penetration | Notes |
|---|---|---|---|---|
| 0 | High cellulose sodium | DCEP | Deep | E6010 — root pass, pipe |
| 1 | High cellulose potassium | AC / DCEP | Deep | E6011 — AC machines |
| 2 | High titania sodium | AC / DCEN | Medium | Fast fill flat/horizontal |
| 3 | High titania potassium | AC / DCEP / DCEN | Light | Easy slag removal |
| 4 | Iron powder titania | AC / DCEP / DCEN | Medium | High deposition efficiency |
| 5 | Low hydrogen sodium | DCEP only | Medium | E7015 — crack-sensitive steels |
| 6 | Low hydrogen potassium | AC / DCEP | Medium | E7016 — general low-H |
| 7 | Iron powder iron oxide | AC / DCEP | Medium | Flat/horizontal high deposition |
| 8 | Low hydrogen iron powder | AC / DCEP | Medium | E7018 — preferred structural electrode |
Suffix Designations
| Suffix | Meaning | Limit / Requirement |
|---|---|---|
| -1 | Improved toughness/ductility | Higher CVN impact requirements at lower temperature |
| H4 | Hydrogen control — tightest | Diffusible H ≤ 4 ml/100 g deposited weld metal |
| H8 | Hydrogen control — standard | Diffusible H ≤ 8 ml/100 g |
| H16 | Hydrogen control — relaxed | Diffusible H ≤ 16 ml/100 g |
| R | Moisture resistance | Meets humidity exposure test (9 h at 80% RH, 27 °C) |
Low-Alloy SMAW — AWS A5.5
AWS A5.5 extends the A5.1 carbon steel system to low-alloy electrodes by adding chemical composition suffixes after the coating digit. For example, E8018-B2 indicates: 80 ksi tensile, all-position, low-hydrogen iron powder coating, with the B2 suffix denoting approximately 1.25% Cr and 0.5% Mo in the deposited weld metal — a common designation for P22 and P91-class chromium-molybdenum steels.
E8018-B2 → 80 ksi | All-pos | LH/Iron powder | 1.25Cr-0.5Mo
E9018-B3 → 90 ksi | All-pos | LH/Iron powder | 2.25Cr-1.0Mo
E8016-B6 → 80 ksi | All-pos | LH/Potassium | 5Cr-0.5Mo
E9015-B9 → 90 ksi | All-pos | LH/Sodium | 9Cr-1Mo-V (P91)
E8018-C1 → 80 ksi | All-pos | LH/Iron powder | 2.5Ni (cryogenic toughness)
E7018-A1 → 70 ksi | All-pos | LH/Iron powder | 0.5Mo (elevated temperature)
GMAW and GTAW Wire Nomenclature — AWS A5.18
Solid filler wires used in Gas Metal Arc Welding (GMAW/MIG) and Gas Tungsten Arc Welding (GTAW/TIG) for carbon and low-alloy steels are classified under AWS A5.18. The designation format is ER XXS-X.
AWS A5.18 Solid Wire Classification Grades
| Designation | Si (%) | Mn (%) | Key Deoxidisers | Best Application |
|---|---|---|---|---|
| ER70S-2 | 0.40–0.70 | 0.90–1.40 | Al + Ti + Zr (triple deox) | Dirty/rusty/oily base metal; killed and semi-killed steel |
| ER70S-3 | 0.45–0.75 | 0.90–1.40 | Standard Si/Mn | Clean base metal; general-purpose |
| ER70S-4 | 0.65–0.85 | 1.00–1.50 | Higher Si/Mn | Better weld pool fluidity on clean steel |
| ER70S-6 | 0.80–1.15 | 1.40–1.85 | High Si + Mn | Mill-scale contaminated steel; most widely used GMAW wire |
| ER70S-7 | 0.50–0.80 | 1.50–2.00 | High Mn, lower Si | High Mn for improved toughness; low-temperature applications |
Stainless Steel Wire — AWS A5.9
Stainless steel solid wires follow a similar ER format under AWS A5.9. The composition classification replaces the S-digit with a steel grade designation. For example, ER308L indicates: ER = electrode/rod, 308L = Type 308 chemistry with low carbon (maximum 0.03% C) for improved resistance to intergranular corrosion and sensitisation. Other common grades include ER316L (molybdenum-bearing, pitting resistance), ER309L (dissimilar metal joining), and ER2209 (duplex stainless steel).
FCAW Wire Nomenclature — AWS A5.20 and A5.29
Flux-Cored Arc Welding (FCAW) wires carry the designation prefix E (electrode) followed by a tensile strength code, T (tubular), a position digit, a usability and performance digit, and one or more suffixes that define shielding gas type, impact toughness, and hydrogen content. Carbon steel FCAW wires are covered by AWS A5.20; low-alloy FCAW wires by AWS A5.29.
FCAW Position and Usability Digits
| Position Digit | Permitted Positions |
|---|---|
| 0 | Flat and horizontal fillet (downhand) only |
| 1 | All positions — flat, horizontal, vertical, overhead |
FCAW Shielding Gas and Performance Suffixes
| Suffix | Meaning | Details |
|---|---|---|
| C | CO₂ shielding gas | 100% CO₂; deeper penetration, higher spatter |
| M | Mixed gas shielding | 75–80% Ar + 20–25% CO₂; smoother arc, less spatter |
| J | CVN impact toughness | Minimum 27 J at -40 °C (instead of standard -20 °C) |
| H4 | Low hydrogen | Diffusible H ≤ 4 ml/100 g weld metal |
| H8 | Standard hydrogen | Diffusible H ≤ 8 ml/100 g weld metal |
SAW Consumable Nomenclature — AWS A5.17 and A5.23
Submerged Arc Welding (SAW) uses a two-part consumable system: a granular flux and a bare wire electrode. AWS A5.17 covers carbon steel SAW consumables; AWS A5.23 covers low-alloy SAW. The combined designation encodes the flux performance followed by the wire classification: F X X X – E X X X.
SAW Flux Classification — Impact Temperature Code
| Code | CVN Impact Test Temperature | Minimum Energy |
|---|---|---|
| Z | No impact requirement | — |
| A | As-welded test only | 27 J |
| P | Post-weld heat treated | 27 J |
| 0 | 0 °C | 27 J |
| 2 | -20 °C | 27 J |
| 3 | -30 °C | 27 J |
| 4 | -40 °C | 27 J |
| 5 | -50 °C | 27 J |
| 6 | -60 °C | 27 J |
SAW Wire Electrode Prefix Codes
| Wire Code | Manganese Level | Nominal Carbon | Notes |
|---|---|---|---|
| EL8 | Low Mn | ~0.08% | For lower heat input applications |
| EL12 | Low Mn | ~0.12% | General purpose, clean welds |
| EM12K | Medium Mn | ~0.12% | Most common SAW wire; K = killed |
| EH14 | High Mn | ~0.14% | High deposition, thick-section work |
ISO and EN Classification Systems
The ISO and European EN standards cover the same welding processes but express properties in metric units and use a different code sequence. When working on projects that specify European or international consumables, cross-referencing is essential. The governing documents are ISO 2560 (covered SMAW electrodes), ISO 14343 (stainless steel wire and strip), ISO 17632 (flux-cored wires), and the parallel European norms EN 499 and EN 12536.
ISO 2560 — SMAW Electrode Format
The ISO 2560 designation reads: ISO 2560-[system]-E [strength class][elongation][impact symbol]-[coating][current]-[H content]. In practice, an electrode broadly equivalent to AWS E7018-H4R would carry a designation such as ISO 2560-B E 50 4 B 42 H5, where:
- B — classification system (B = AWS-aligned; A = ISO/EN aligned)
- E 50 — electrode, 500 MPa minimum yield strength (vs 70 ksi ≈ 483 MPa tensile in AWS)
- 4 — elongation and impact requirement class
- B — basic (low-hydrogen) coating
- 42 — impact toughness: 47 J at -20 °C
- H5 — diffusible hydrogen ≤ 5 ml/100 g (comparable to AWS H4)
Quick Cross-Reference: AWS to ISO/EN
| Process | AWS Designation | Approx. ISO/EN Equivalent | Standard |
|---|---|---|---|
| SMAW | E7018-H4R | E 46 4 B 42 H5 (EN 499) | EN 499 / ISO 2560 |
| SMAW | E6010 | E 42 0 C 1 (EN 499) | EN 499 / ISO 2560 |
| GMAW/GTAW | ER70S-6 | G 42 4 M G4Si1 (EN ISO 14341) | EN ISO 14341 |
| GMAW/GTAW | ER308L | G 19 9 L (EN ISO 14343) | EN ISO 14343 |
| FCAW | E71T-1M | T 46 4 PM1 H10 (EN ISO 17632) | EN ISO 17632 |
F-Numbers and A-Numbers in ASME Section IX
When qualifying welding procedures under ASME Section IX, consumables are grouped by F-Numbers (filler metal groups, QW-432) and the deposited weld metal composition is tracked by A-Numbers (QW-442). Understanding how standard AWS designations map to these ASME groupings is critical for managing the scope of PQR qualification.
| F-Number | Consumable Type | Example Designations |
|---|---|---|
| F-1 | High-cellulose sodium electrodes | E6010 |
| F-2 | High-titania electrodes | E6012, E6013 |
| F-3 | Low-hydrogen electrodes | E7015, E7016, E7018 |
| F-4 | Iron powder, low-hydrogen electrodes | E7028, E7048 |
| F-6 | Solid and composite filler wire — carbon/low-alloy steel | ER70S-2, ER70S-6 |
| F-41 to F-45 | Stainless steel electrodes | E308L-16, E316L-16, E309L-16 |
| F-43 | Stainless solid wire | ER308L, ER316L, ER309L |
A-Numbers classify the analysis of the weld metal deposit. A-Number 1 covers carbon steel welds (C-Mn-Si), A-Number 8 covers austenitic stainless welds (308, 308L, 309, 316L, etc.). Changes in A-Number require requalification of the WPS. See the full P-Number, F-Number, and A-Number guide for a complete reference table.
Quick Reference Summary
| Process | Example Designation | Standard | Min. Tensile | Position | Shielding | Key Notes |
|---|---|---|---|---|---|---|
| SMAW | E7018-H4R | AWS A5.1 / SFA-5.1 | 70 ksi (483 MPa) | All | Flux coating | H≤4 ml/100g; moisture resistant; preferred structural electrode |
| SMAW | E6010 | AWS A5.1 / SFA-5.1 | 60 ksi (414 MPa) | All | Flux coating | Cellulosic; deep penetration; DCEP only; pipe root passes |
| GMAW | ER70S-6 | AWS A5.18 / SFA-5.18 | 70 ksi (483 MPa) | All | Ar+CO₂ or CO₂ | High Si+Mn; tolerant of mill scale; most common GMAW wire |
| GTAW | ER70S-2 | AWS A5.18 / SFA-5.18 | 70 ksi (483 MPa) | All | Argon (TIG) | Triple deoxidised; best for contaminated base metal |
| FCAW | E71T-1M-H8 | AWS A5.20 / SFA-5.20 | 71 ksi (490 MPa) | All | Ar+CO₂ mixed | Smooth arc; lower spatter than CO₂; H≤8 ml/100g |
| FCAW | E71T-1C | AWS A5.20 / SFA-5.20 | 71 ksi (490 MPa) | All | 100% CO₂ | Deeper penetration; higher spatter; economical shielding |
| SAW | F7A2-EM12K | AWS A5.17 / SFA-5.17 | 70 ksi (483 MPa) | Flat only | Granular flux | CVN ≥27 J at -20 °C; medium Mn wire; pressure vessel work |
Hydrogen Control in Practice
Hydrogen-induced cold cracking (HICC) — also called delayed cracking or underbead cracking — occurs when sufficient diffusible hydrogen, residual stress, and a susceptible microstructure coincide in the heat-affected zone. The consumable designation is the first indicator of the expected diffusible hydrogen level, but proper handling in the field is equally critical.
H4 → ≤ 4 ml / 100 g deposited weld metal — Tightest control
H8 → ≤ 8 ml / 100 g deposited weld metal — Standard low-H
H16 → ≤ 16 ml / 100 g deposited weld metal — Relaxed control
Recommended Preheat Increases if H-Level is Elevated
Switching from H4 to H8 may require preheat increase of 25-50 °C depending on CE.
See Carbon Equivalent (CE) calculator at WeldFabWorld for combined preheat assessment.
Electrode Oven Conditioning (Low-Hydrogen SMAW)
Re-drying: 300–400 °C for 1–2 hours (per manufacturer)
Holding oven: 65–150 °C during welding operations
Electrodes exposed to humidity beyond the permitted window must be re-dried or rejected.
The R suffix (e.g. E7018-H4R) indicates the electrode was tested under humidity exposure (80% RH at 27 °C for 9 hours) and still met its hydrogen classification. This is particularly important on outdoor construction sites and in humid tropical climates. You can assess the preheat requirement for a given base material using the Carbon Equivalent (CE) Calculator on WeldFabWorld.
Worked Decode Examples
Example 1 — Decode E8018-B2-H4
E → Covered electrode for SMAW
Step 2: Tensile strength
80 → Minimum tensile strength = 80 ksi (552 MPa)
Step 3: Position digit
1 → All positions (flat, horizontal, vertical, overhead)
Step 4: Coating/current digit
8 → Low-hydrogen iron powder coating; AC or DCEP
Step 5: Alloy suffix (AWS A5.5)
B2 → ~1.25% Cr + ~0.5% Mo in deposited weld metal
Step 6: Hydrogen suffix
H4 → Diffusible hydrogen ≤ 4 ml / 100 g
Result: All-position, low-hydrogen, 80 ksi 1.25Cr-0.5Mo electrode for P22 / ASTM A387 Gr.11 welding
Example 2 — Decode F9P4-ECrMo2-B2 (SAW, AWS A5.23)
F → Flux
9 → 90 ksi minimum tensile in deposited weld
P → Tested in post-weld heat treated condition
4 → CVN ≥ 27 J at -40 °C
Wire portion: ECrMo2-B2
E → Electrode wire
CrMo2 → Chromium-Molybdenum alloy composition class
B2 → ~1.25Cr-0.5Mo (aligns with SMAW B2 suffix convention)
Result: SAW flux-wire combination for 1.25Cr-0.5Mo pressure vessel SAW; PWHT condition; -40 deg C toughness
Estimating Consumable Requirements
Understanding the designation is only part of the task — you also need to estimate how much consumable a given joint will require. For V-groove butt welds, WeldFabWorld provides a dedicated V-Groove Consumable Calculator that calculates electrode or wire weight per metre of weld based on joint geometry, deposition efficiency, and wire diameter. For fillet welds, use the Fillet Weld Consumable Calculator. Both tools account for process-specific deposition efficiencies:
| Process | Typical Deposition Efficiency | Notes |
|---|---|---|
| SMAW | 60–70% | Coating stub and spatter loss reduce efficiency |
| GMAW (spray) | 90–98% | Highest efficiency for solid wire |
| FCAW-G | 80–88% | Some core flux is consumed as slag |
| GTAW | 95–99% | Near-complete filler use; no spatter |
| SAW | 95–99% | Very high efficiency; flux is partly recovered |
Recommended Reference Books
Frequently Asked Questions
What does the ‘E’ prefix mean in welding electrode designations?
The ‘E’ prefix stands for Electrode. It indicates that the consumable is capable of carrying electrical current and is used as an arc welding electrode. In SMAW designations like E7018, the E simply confirms the product is a covered electrode. In FCAW designations the E similarly identifies a tubular flux-cored electrode. In GMAW/GTAW designations the ‘ER’ prefix indicates the wire functions as both an Electrode and a filler Rod — it carries current in GMAW but is used as a non-energised rod in GTAW.
What is the difference between ER70S-2 and ER70S-6 wires?
Both wires share the same 70 ksi minimum tensile strength but differ fundamentally in deoxidiser content and intended base metal surface condition. ER70S-2 contains triple deoxidisers — aluminium, titanium, and zirconium — and is best for welding on dirty, rusty, or oily base metals where porosity risk from surface contamination is high. ER70S-6 is enriched in silicon (0.80–1.15%) and manganese (1.40–1.85%), making it tolerant of mill scale and producing a fluid, easily controlled weld pool with good wetting. ER70S-6 is the most widely used GMAW wire for structural carbon steel work due to its excellent bead appearance and arc stability.
What does the H4 suffix mean on a low-hydrogen SMAW electrode?
The H4 suffix in designations like E7018-H4 indicates that the electrode has been tested and certified to deliver a maximum diffusible hydrogen content of 4 ml per 100 g of deposited weld metal. Lower hydrogen content reduces the risk of hydrogen-induced cold cracking (HICC), which is particularly critical when welding higher-strength steels, thick sections, or highly restrained joints. The H4 designation represents the tightest hydrogen control category in AWS A5.1; H8 and H16 are progressively less strict. For P91 and other high-Cr-Mo steels, H4 is typically the mandatory minimum.
What does the ‘R’ suffix mean in SMAW electrode nomenclature?
The ‘R’ suffix indicates that the electrode has passed the moisture absorption resistance test defined in AWS A5.1. An electrode bearing the R designation has been conditioned to its rated hydrogen level, then exposed to a humid environment (80% relative humidity at 27 deg C for 9 hours), and still meets the stated hydrogen limit after this exposure. This is particularly important for field welding and offshore fabrication where electrodes may be stored in less-than-ideal conditions before use. Without the R suffix, the same electrode type may absorb enough moisture during storage to effectively nullify its H4 certification — which can lead to cold cracking in service-critical welds.
How do you read the SAW consumable designation F7A2-EM12K?
The designation F7A2-EM12K is read in two parts. F7A2 describes the flux performance: F means flux, 7 means the flux-wire combination deposits weld metal with minimum 70 ksi tensile strength, A means the properties were determined in the as-welded (not PWHT) condition, and 2 means the flux delivers at least 27 J Charpy impact toughness at -20 deg C. EM12K describes the electrode wire: E is electrode, M indicates medium manganese content (~0.7–1.0%), 12 indicates approximately 0.12% carbon, and K indicates the wire is made from aluminium-killed steel, giving a clean, consistent composition. Together they specify a complete flux-wire combination suitable for submerged arc welding of pressure vessel shells and structural work requiring -20 deg C toughness in the as-welded condition.
What is the difference between E71T-1C and E71T-1M FCAW wires?
Both E71T-1C and E71T-1M are all-position flux-cored wires with a minimum 71 ksi tensile strength and a positional capability (digit 1) for all positions. The critical difference is shielding gas compatibility. The C suffix indicates the wire is designed for use with 100% CO2 shielding gas, which provides deeper penetration but generates higher spatter and a rougher bead appearance. The M suffix indicates a mixed gas shield — typically 75–80% Ar blended with 20–25% CO2 — which produces a smoother, more controlled arc with significantly lower spatter and better out-of-position performance. The M variant is generally preferred for applications requiring superior bead appearance, tighter dimensional control, or frequent positional changes on pipe and structural work.
How does ISO 2560 differ from AWS A5.1 for SMAW electrode classification?
ISO 2560 and AWS A5.1 both classify covered SMAW electrodes for carbon and carbon-manganese steel welding but use different code formats and unit systems. AWS A5.1 uses the E-XXXX format where the digits encode tensile strength in ksi, welding position, and the coating/current type in a fixed sequence. ISO 2560 uses a more detailed alphanumeric sequence that separately encodes strength class, minimum elongation, Charpy impact temperature, coating type, current suitability, and diffusible hydrogen in distinct code fields. ISO 2560 expresses strength in MPa, not ksi. An electrode broadly equivalent to AWS E7018-H4R would carry an ISO 2560 designation of approximately E 46 4 B 42 H5. When substituting between AWS and ISO electrodes on code-controlled work, always verify against the specific SFA specification requirements in ASME Section II Part C.
Which ASME standard governs welding consumable specifications?
ASME Section II Part C (Materials — Welding Rods, Electrodes, and Filler Metals) governs welding consumable specifications for ASME-coded pressure vessel and piping fabrication. The SFA designations in ASME Section II Part C directly adopt the AWS A5.X series specifications with minor ASME-specific supplements. For example, ASME SFA-5.1 corresponds to AWS A5.1, SFA-5.18 to AWS A5.18, and SFA-5.20 to AWS A5.20. When qualifying welding procedures under ASME Section IX, only consumables that conform to the applicable SFA specification may be used without additional qualification testing. Consumables with supplemental requirements are identified in the SFA specification appendices.