Electrode and wire designations explained

Type the designation off the box — E7018, ER70S-6, E 42 5 B 42 H5 — and it gets pulled apart field by field, with each one explained. Below are the full code tables to EN ISO and AWS.

Works for covered electrodes and for wires, in both the European and the American notation. EN ISO designations are written with spaces, American ones run together.

Covered electrodes to EN ISO 2560

Read it left to right: the type letter, strength, impact toughness, chemistry, covering, deposition yield with the current, positions and hydrogen at the end. The first two figures are the ones that matter — they say which steel the electrode belongs to.

E 42 5 B 42 H5

Covered electrodes to AWS A5.1

Four digits after the letter E: the first two are the tensile strength in thousands of pounds per square inch, the third is the positions, the fourth is the covering together with the current. That is why E7018 and E6013 differ in more than strength.

E 70 1 8

Solid wire: EN ISO 14341 and AWS A5.18

In the European notation the letter G is followed by strength, toughness, shielding gas and wire chemistry. The American ER70S-6 says the same thing more briefly: 70 ksi, solid wire, chemistry number six.

G 42 3 M21 3Si1   ER 70 S -6

Flux-cored wire and stainless electrodes

On flux-cored wire the letter T is followed by the core type — that decides whether the bead comes out smooth and how little hydrogen stays in the weld. On stainless electrodes the two digits after the dash are the covering and the current.

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Wall sheet

E 42 3 B 32 H5 — an EN ISO 2560 designation taken apart

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A covered-electrode designation to EN ISO 2560-A is read left to right, and every field points to one of the tables above. Take E 42 3 B 32 H5:

1. E — covered electrode for manual metal arc welding (111).
2. 42 — weld metal yield strength at least 420 MPa, tensile strength 500–640 MPa.
3. 3 — 47 J impact energy reached at −30 °C.
4. no chemistry symbol — unalloyed carbon-manganese weld metal; an alloyed electrode would carry a symbol such as 1Ni or Mo here.
5. B — basic covering: low hydrogen, good toughness, needs dry storage.
6. 3 — recovery 105–125 %, AC and DC.
7. 2 — all positions except vertical down.
8. H5 — diffusible hydrogen up to 5 ml/100 g of weld metal.

Compare it with the decoder's example, E 42 5 B 42 H5: same strength and covering, but toughness at −50 °C, and the 4 in the recovery place means DC only. Anyone with an AC transformer set cannot run it, although on the box the difference is a single digit.

The A after the standard number (EN ISO 2560-A) means classification by yield strength and 47 J impact. System B of the same standard classifies by tensile strength and 27 J, and its designations look American: E4918 is the counterpart of AWS E7018.

E7018, E6013, E7018-1 H4R: reading AWS A5.1 designations

In AWS the letter E is followed by four digits. The first two are the tensile strength in thousands of psi: 60 is about 430 MPa, 70 about 490 MPa. The third is the positions, the fourth the covering together with the current:

• E7018 — 490 MPa, all positions, basic covering with iron powder, AC or DC electrode positive. The standard choice for structural work.
• E6013 — 430 MPa, all positions, rutile potassium covering, AC and DC of either polarity. Easy to strike and forgiving of an uneven gap, but lower in toughness.
• E7016 — the same strength as E7018, basic potassium covering without iron powder, so it deposits more slowly.

Suffixes may follow: -1 on E7018 means improved toughness; H4, H8 or H16 give the maximum diffusible hydrogen in ml/100 g; R marks a moisture-resistant covering. So E7018-1 H4R is a basic electrode with improved toughness, no more than 4 ml of hydrogen, and resistant to moisture pick-up.

G 42 3 M21 3Si1 and ER70S-6: MIG/MAG wires

A solid wire to EN ISO 14341-A starts with G, followed by strength, toughness, gas and composition:

• G — solid wire for gas-shielded welding.
• 42 — weld metal yield strength at least 420 MPa.
• 3 — 47 J impact at −30 °C.
• M21 — the gas used for the classification tests: Ar + 15–25 % CO₂. The same wire in pure CO₂ (C1) may give different properties.
• 3Si1 — composition: silicon and manganese, the commonest variant.

The American ER70S-6 says the same more briefly: ER — electrode or rod, 70 ksi, S — solid, 6 — the composition with the highest silicon and manganese. In the shop it is usually paired with G3Si1, but for acceptance what counts is the wire's certificate. The shielding gas selector helps match the gas to the wire.

What else to check on the box

The designation describes the weld metal, not everything you need at the bench. Read these off the packaging too:

• diameter and length — e.g. 3.2 × 350 mm; the diameter sets the current, which the current calculator works out;
• the maker's current range and polarity — often narrower than the current digit in the designation alone suggests;
• re-drying conditions — temperature and time from the manufacturer for basic electrodes; without them the H5 on the box means nothing;
• the batch number — needed for acceptance documents (such as an EN 10204 3.1 certificate) and for complaints.

Covering types and how they behave are covered in the article on electrode coverings, and real brands with their designations in the electrode catalogue.

Common mistakes when reading designations

1. ISO 42 read like AWS 70. In EN ISO 2560-A the number is yield strength in MPa/10; in AWS it is tensile strength in ksi. E 42 and E70 measure different things.
2. Position digits mixed up. In ISO 1 is all positions and 3 is flat and horizontal fillet; in AWS 1 is also all positions, but 2 is flat and horizontal. Read each system with its own table.
3. The current digit ignored. Even recovery digits (2, 4, 6, 8) in ISO mean DC only.
4. E6013 on a load-bearing structure. A rutile electrode is pleasant to run, but critical joints get a basic one such as E7018.
5. H5 without re-drying. The hydrogen figure applies to a dry electrode; after a night in a damp shop it is a different electrode.

What the designation will not tell you

The code describes the deposited metal, not your joint. It holds no plate thickness, no preheat, and no record of whether the electrode was baked — the current range, re-drying conditions and batch are read off the box, as listed above.

Author: Dmitry Frolov, welder and metal fabricator Updated: 28 September 2026