The classification stamped on a welding rod, spool, or carton is not random. It is a compact code defined by the American Welding Society that tells you the process, the strength, the position you can run it in, and how it behaves. Once you can read it, you can pick the right filler with confidence and spot a wrong substitution before it costs you a weld. This guide walks through the carbon steel stick code first, because it teaches the pattern, then covers solid wire, flux cored, and stainless.
The Anatomy of a Stick Electrode Number
Take E7018. Reading left to right:
- E means electrode.
- 70 is the minimum tensile strength of the deposited weld metal in ksi, so 70,000 psi.
- 1 is the welding position.
- 18 (the last two digits taken together) sets the coating type and the welding current.
A five-digit number like E11018 works the same way, the strength is just three digits (110 ksi). The trap is reading the last two digits separately. They are a pair. The first of the pair is the position and both together name the coating and current.
AWS Welding Electrode Decoder
Decode any AWS filler-metal classification: stick electrodes (E6010, E7018, E8018-B2), flux cored wire (E71T-1, E70T-4), solid wire (ER70S-6), and stainless (E308L-16, ER316L). Reads each digit and letter for tensile strength, welding position, current and polarity, coating type, and low-hydrogen status, with the storage and base-metal field notes the chart leaves out. Source-cited to AWS A5.1, A5.4, A5.5, A5.9, A5.18, and A5.20.
The Position Digit
The next-to-last digit is the position the electrode is qualified to run:
- 1 all positions: flat, horizontal, vertical, and overhead.
- 2 flat and horizontal fillet only.
- 4 flat, horizontal, overhead, and vertical-down (downhill).
That is why E7018 (all positions) and E7028 (flat and horizontal) are different rods even though both are 70 ksi low-hydrogen iron-powder electrodes. The 7028 lays down more metal fast in the flat, but it will not run a vertical-up bead.
The Last Two Digits: Coating and Current
The last two digits, read together, identify the flux coating and the current it needs:
- 10 high-cellulose sodium, DCEP, deep penetration. The classic 6010 root-pass and pipe rod.
- 11 high-cellulose potassium, AC or DCEP. The AC-capable cousin of 6010.
- 12 / 13 rutile (titania), softer arc, light penetration, good on sheet and poor fitup.
- 14 / 24 rutile plus iron powder, higher deposition.
- 15 / 16 / 18 low-hydrogen, for crack-sensitive and higher-strength steel. 7018 is the 18.
- 20 / 24 / 27 / 28 high-deposition rods for flat and horizontal production.
Low-Hydrogen and Why It Must Stay Dry
The low-hydrogen stick coatings (15, 16, 18, 28, 48) produce a deposit with very little diffusible hydrogen, which is what you want on higher-strength steel and restrained joints, because hydrogen is what drives delayed cracking. But the coating only delivers low hydrogen if it is dry. A 7018 left out in a humid shop pulls moisture into the flux, and that moisture becomes hydrogen in the arc. Keep low-hydrogen rod in a heated rod oven, limit how long it sits in open air, and rebake or discard per the manufacturer if it has been exposed.
Solid Wire and Flux Cored
Wire codes read a little differently. ER70S-6 is a solid wire: ER means it can feed as a MIG electrode or be cut into TIG rods, 70 is the tensile strength, S means solid, and the dash number (6) is the deoxidizer class. A -6 has the most manganese and silicon, so it wets out well and tolerates mill scale, which is why it is the default shop wire.
E71T-1 is flux cored: 7 is the tensile, 1 is the position (all positions), T means tubular, and the dash number is the usability class. A -1 is rutile, gas-shielded, runs on DCEP, and is smooth with low spatter. Self-shielded flux cored wires like E71T-8 and E71T-11 make their own shielding and need no gas bottle, which is why they show up on outdoor field structural work where wind would blow shielding gas away.
Stainless Filler
Stainless classifications name the deposited alloy, not a strength. E308L-16 is a covered electrode: 308 is the deposit type (matches 304 base metal), L is low carbon, and 16 is a rutile coating that runs on AC or DCEP. ER316L is a bare wire or rod: 316 deposit (adds molybdenum for pitting resistance), low carbon. Use 309 to join stainless to carbon steel or for the first overlay layer. The L matters anywhere the weld will see corrosion, because low carbon resists sensitization in the heat-affected zone.