Welding reference
AWS Filler Metal Designation Decoder (E7018, ER70S-6, E71T-1)
Every AWS filler metal designation answers four questions in order: how strong the deposited metal must be, which positions the consumable is classified for, what the coating or wire chemistry is, and therefore what current it wants. Type a designation such as E7018, ER70S-6, E71T-1 or E308L-16 and each position is spelled out, with the minimum tensile strength given in both ksi and MPa.
Enter a designation, e.g. E7018, ER70S-6 or E71T-1
| Position | Code | Meaning |
|---|
How it works
Stick electrodes under A5.1 carry the strength directly. In E7018 the 70 is 70 ksi minimum tensile, the 1 says all positions, and the 8 is a low hydrogen potassium coating with iron powder that runs on AC or DC electrode positive. Change the third digit to 2 and the electrode is classified for flat and horizontal fillets only, which is why E7024 lays down so much metal and cannot be run vertically. Add a suffix and the electrode moves to A5.5, where -A1 means carbon molybdenum and -B2 means a 1.25 chromium 0.5 molybdenum alloy for hot service.
Flux cored wire is where readers get caught. A5.20 states the strength as a SINGLE digit in tens of ksi, so the 7 in E71T-1 is 70 ksi, exactly the same strength as E7018 written a different way. The T marks it tubular, the digit before the T is the position, and the number after the dash is the usability designator that decides whether it needs shielding gas at all. Solid wire under A5.18 uses the plain ksi number followed by S for solid, then a composition classifier: the 6 in ER70S-6 is the highest silicon and manganese of the common set, which is why it wets over mill scale. Stainless drops strength from the designation entirely and names the alloy type instead.
Worked example
E7018 reads as 70 ksi (483 mpa) minimum tensile strength, classified for all positions, on a low hydrogen potassium covering with iron powder that runs on AC or DC electrode positive. The same 70 ksi written in the flux cored A5.20 form is E71T-1, where the single 7 means tens of ksi. Two designations, one strength, two different places to read it.
Frequently asked questions
What does the 18 in E7018 mean?
The 1 and the 8 are two separate facts. The 1 is the position digit and means the electrode is classified for all positions including vertical and overhead. The 8 is the coating designator and means a low hydrogen potassium covering with iron powder added, which runs on alternating current or on direct current electrode positive.
Is E71T-1 the same strength as E7018?
Yes, both deposit weld metal with a 70 ksi minimum tensile strength, but the classifications write it differently. A5.1 stick electrodes state the full number, so E7018 shows 70. A5.20 flux cored wires state tens of ksi in a single digit, so the 7 in E71T-1 also means 70. Reading that 7 as 7 ksi is the most common misreading of the whole system.
What does the S in ER70S-6 stand for?
S means the wire is solid rather than tubular or cored. The number after the dash is a composition classifier, not a strength: 6 carries the highest silicon and manganese of the common carbon steel wires, which is what lets it wet out over mill scale and light rust where a lower silicon wire such as ER70S-3 would sit up on the surface.
Why does a stainless designation have no strength number?
Austenitic stainless classifications name the alloy type instead, because the strength follows the chemistry. E308L-16 is a 308 composition with low carbon and a titania coating; the mechanical properties come from that alloy rather than from a number in the designation. The trailing 16 is the coating and current designator, not a strength.
What does the L mean on 308L or 316L?
L means low carbon, at most 0.03 percent. Keeping carbon low limits chromium carbide precipitation at the grain boundaries when the weld cools through the sensitisation range, which is what causes intergranular corrosion in service. It is the default choice for welded stainless unless elevated temperature strength is specifically wanted.
Does this decode every AWS classification?
It decodes the common carbon steel, low alloy, flux cored and austenitic stainless families that a general fabrication shop buys. Aluminium, nickel, hardfacing and the full low alloy suffix matrix are not covered, and the exact composition limits behind a suffix live in the AWS standard itself rather than here.
Related calculators
Coverage
Implements AWS A5.1, A5.4, A5.5, A5.9, A5.18 and A5.20 (carbon, low alloy, stainless and flux cored): Specification and process identified from the designation form, Minimum tensile strength in ksi and MPa, including the tens-of-ksi flux cored form, Position digit, coating or chemistry classifier, and the resulting current, Common A5.5 alloy and hydrogen suffixes named by chemistry family. Deliberately not offered yet:
- Composition limits and impact toughness values behind each classification - these are tabulated in the AWS A5 standards, which are sold by AWS; the numbering system is documented freely by makers but the tables are not ours to reproduce
- Aluminium (A5.10), nickel (A5.11 and A5.14) and hardfacing consumables - different numbering conventions; not attempted rather than half decoded
- The full A5.5 suffix matrix beyond the common A, B, C, D, G, M and hydrogen designators - single-sourced in the free literature; not asserted as certified without the standard
Sources
- Basics of AWS filler metal and stick electrode classification (Hobart Brothers)
- Understanding the SMAW electrode symbols, position and flux digits (Welding and NDT)
- AWS classifications of filler metals across the A5 series (Material Welding)
- Stick welding polarity by electrode class (Material Welding)
Every formula on this page is shown and sourced. See how we verify.
These calculators are for planning and as a starting point. Recommended speeds and feeds are published starting values that vary with your specific tool, coating, machine rigidity, workholding and coolant. Always start conservative, listen to the cut, and follow your tool maker data sheet.