Guide
What Welding Electrode Numbers Mean
In a stick electrode number like E7018, E means electrode, 70 means 70,000 psi tensile strength, 1 means all positions, and 8 means a low-hydrogen coating usable on AC or DCEP.
AWS filler metal classifications look cryptic but they are systematic. Each position in the number carries one piece of information, and once you know the pattern you can read the properties of a rod you have never used from the box alone.
Carbon steel stick electrodes: AWS A5.1
A four or five digit number after the E, as in E7018.
| Digit | Meaning | Example |
|---|---|---|
| E | Electrode for shielded metal arc welding | E7018 |
| First two (or three) digits | Minimum tensile strength in thousands of psi | 70 = 70,000 psi |
| Third digit | Welding positions | 1 = all positions, 2 = flat and horizontal fillets, 4 = all positions including vertical-down |
| Fourth digit | Coating type and usable current | 8 = low-hydrogen potassium with iron powder, AC or DCEP |
The last digit in full
| Digit | Coating | Current |
|---|---|---|
| 0 | High-cellulose sodium | DCEP only |
| 1 | High-cellulose potassium | AC or DCEP |
| 2 | High-titania sodium | AC or DCEN |
| 3 | High-titania potassium | AC, DCEP or DCEN |
| 4 | Iron-powder titania | AC, DCEP or DCEN |
| 5 | Low-hydrogen sodium | DCEP only |
| 6 | Low-hydrogen potassium | AC or DCEP |
| 7 | High iron oxide, iron powder | AC, DCEP or DCEN |
| 8 | Low-hydrogen potassium, iron powder | AC or DCEP |
The last two digits work together. In E6010 the 1 means all positions and the 0 means cellulosic sodium on DCEP. In E7024 the 2 means flat and horizontal fillets only, which is why that rod cannot be run vertical no matter how good you are.
Optional suffixes
A suffix after the main number adds a requirement. E7018-1 meets a lower impact test temperature, 20 ft·lb at -50 °F instead of -20 °F. An H4 or H8 designator caps diffusible hydrogen at 4 or 8 millilitres per 100 grams of deposited metal. An R indicates a moisture-resistant coating with a longer permitted atmospheric exposure.
Stainless covered electrodes: AWS A5.4
Stainless classifications use the alloy designation rather than a strength code, as in E308L-16.
- E — covered electrode.
- 308, 309, 316, 347, 410 — the nominal alloy, matching the AISI base metal grade of the same number.
- L — low carbon, 0.04% maximum, to resist carbide precipitation. An H suffix means higher carbon for elevated-temperature strength.
- -15 — lime coating, DCEP only. -16 — lime-titania coating, AC or DCEP. -17 — silica-bearing coating with a more fluid puddle.
Solid wire: AWS A5.18 and A5.9
Carbon steel solid wire follows the pattern ER70S-6.
- ER — usable as both a continuously fed electrode and a hand-fed rod, so it covers MIG and TIG.
- 70 — 70,000 psi minimum tensile strength of the deposited weld metal.
- S — solid wire.
- 6 — a chemistry designation. In the ER70S family, higher numbers generally carry more deoxidisers; ER70S-6 has the highest silicon and manganese and therefore the best tolerance for mill scale.
Stainless bare wire drops the strength code and uses the alloy directly: ER308L, ER316L, ER309L. Aluminium bare wire uses the Aluminum Association alloy number: ER4043, ER5356.
Flux-cored wire: AWS A5.20
Flux-cored classifications follow the pattern E71T-1.
| Part | Meaning |
|---|---|
| E | Electrode |
| 7 | 70,000 psi minimum tensile strength |
| 1 | All positions (0 means flat and horizontal only) |
| T | Tubular — flux-cored wire |
| -1 | Usability designator: rutile slag, gas shielded, DCEP, 20 ft·lb at 0 °F |
| -11 | Usability designator: self-shielded, DCEN, no impact requirement |
The usability designator after the T is the part that matters most in practice. It sets the shielding requirement and the polarity, which is why E71T-1 and E71T-11 need opposite polarity settings despite looking almost identical on the label.
Frequently asked questions
What does the 18 in E7018 mean?
The 1 means the electrode can be used in all welding positions. The 8 means a low-hydrogen potassium coating with iron powder, usable on AC or DCEP.
What does the 60 in E6010 mean?
60,000 psi minimum tensile strength of the deposited weld metal. E7018's 70 means 70,000 psi.
What does the L mean in E308L?
Low carbon, 0.04% maximum for covered electrodes and 0.03% for bare wire. Less carbon means less chromium carbide forms at the grain boundaries, which preserves corrosion resistance.
What does ER stand for in ER70S-6?
Electrode or Rod — the filler qualifies both as a continuously fed electrode for MIG and as a hand-fed rod for TIG.
Why do E71T-1 and E71T-11 use different polarity?
The usability designator after the T defines the shielding and polarity. The -1 wire is gas shielded and runs DCEP; the -11 wire is self-shielded and runs DCEN.