SMAW electrode selection: E6010, E7016, E7018 for structural fab

Shielded metal arc welding (SMAW) may be the oldest arc welding process in commercial use, but electrode selection still trips up experienced fabricators when they move to new base metals, new joint configurations, or new code editions. AWS D1.1:2025 has specific requirements about which SMAW electrodes are preapproved and for what applications — getting this right before writing the WPS saves requalification costs.

This article focuses on the four electrodes that account for the large majority of structural SMAW work: E6010, E6013, E7016, and E7018. Understanding the differences — chemically, mechanically, and code-wise — is a prerequisite for building a WPS that survives audit.

The cellulosic vs. low-hydrogen divide

SMAW electrode coatings fall into two broad families based on their chemistry and moisture content:

Cellulosic coatings (E6010, E6011, E6013) contain high amounts of cellulose in the flux, which produces a deep-penetrating, forceful arc with high hydrogen levels in the weld deposit. The high hydrogen is a feature, not a bug — it improves arc penetration through mill scale and rust, making these electrodes excellent for root passes in open-root joints and field repair on less-than-ideal surfaces. But that same hydrogen creates cracking risk in susceptible base metals.

Low-hydrogen coatings (E7016, E7018, E8018, E9018) use a lime-fluoride (basic) flux with minimal moisture-bearing compounds. The result: much lower diffusible hydrogen levels in the deposit. These electrodes require dry storage and, for some alloys, pre-baking before use — but they are the required choice for most structural steel above A36 grade.

The dividing line in AWS D1.1:2025 is not the electrode type alone — it is the combination of electrode type and base metal properties. The code's preheat requirements in Clause 7 (or the applicable table) reference base metal category and carbon equivalent, which then reference process hydrogen level. Low-hydrogen process is typically required when carbon equivalent rises above a threshold and base metal thickness or restraint is significant.

E6010: the root pass workhorse

E6010 is a cellulosic electrode classified for use on DC+ (DCEP) only. Its characteristics:

• Penetration: The cellulosic arc drives deep into the joint root, bridging gaps and fusing root faces even in less-than-perfect fit-up.
• Positional capability: All-position (1G, 2G, 3G, 4G, 1F through 4F), making it useful for field work and out-of-position joints.
• Surface tolerance: Performs better than low-hydrogen electrodes on surface contamination — rust, mill scale, zinc primer — because the aggressive arc burns through surface films.
• Slag characteristics: Thin slag that is easy to remove; the weld face is somewhat coarse but adequate for root pass quality.

Where E6010 fits in AWS D1.1:2025: E6010 is preapproved in AWS D1.1:2025 for SMAW root passes in CJP groove welds, particularly where open-root technique is used with back-side access for back gouging or where steel backing will be left in place. Verify the specific filler metal preapproval table in the 2025 edition for your joint type.

Where E6010 does not fit: On higher-strength steels (A514, A709 HPS 70W, A913 Grade 65+), the cellulosic hydrogen level is incompatible with the base metal's HAZ sensitivity. E6010 root passes on these materials require preheat levels that negate the fit-up forgiveness advantage, and low-hydrogen fill and cap passes create a procedure complication. For high-strength structural steel, the better practice is to use low-hydrogen electrodes throughout — an E7018 or E8018 root on a cleaner joint with tighter tolerances.

E6011: Similar to E6010 but AC-compatible. Sees limited use in structural fab where DC machines are standard. Same hydrogen concerns apply.

E6013: Often labeled "general purpose" and marketed as easy-starting. The coating produces low penetration and a smooth, cosmetic bead — useful for thin sheet metal and light fitment, not appropriate for structural groove welds. AWS D1.1:2025 does not list E6013 as a preapproved filler for prequalified structural WPS. Avoid E6013 in structural applications.

E7016 and E7018: the low-hydrogen pair

Both E7016 and E7018 are low-hydrogen electrodes delivering 70 ksi (480 MPa) minimum tensile strength in the deposit. The critical difference is the coating:

E7016 (low-hydrogen potassium): The potassium-bearing flux allows operation on both AC and DC+. Deposition efficiency is moderate. Common in situations where only AC power is available — older field machines, remote generators. Less common in production shops with DC equipment.

E7018 (low-hydrogen potassium, iron powder): The iron powder addition increases deposition efficiency and makes E7018 the production favorite. The smooth arc and fast deposition rate reduce labor cost per foot of weld. Requires DC+ in most applications, though some E7018 classifications are AC-rated.

For structural SMAW WPS development on A36, A572, and A992, E7018 is the default electrode choice in nearly every shop. The WPS should specify the classification (E7018 or E7018-1 for improved notch toughness), the applicable AWS A5.1 or A5.5 specification, and the hydrogen designator (H4, H8, or H16) when a low-hydrogen requirement applies.

E7018-1 is a variant with improved Charpy V-Notch impact requirements — specified where CVN testing is required per AWS D1.1:2025 Table 6.8 supplementary essential variables. If your project invokes CVN supplementary essentials under Table 6.8, verify that your electrode classification meets the CVN requirements for the test temperature.

E8018 and above: high-strength applications

When base metal strength exceeds what E7018 filler metal can match, higher-strength electrodes enter:

E8018 (80 ksi minimum tensile): Required for WPS development on A572 Grade 65, A913 Grade 65, some A709 HPS grades, and A514 used in higher-stress applications where undermatching is not acceptable to the designer. E8018-C3 is a common variant with nickel alloying for notch toughness.

E9018, E10018, E11018: Used for high-strength quenched-and-tempered steels including A514, A709 HPS 100W, and A517. These require PQR-supported WPS qualification — they are not prequalified under AWS D1.1. The welding parameters, preheat, and interpass temperature controls are tighter, and the hydrogen control requirements are more demanding.

A change from E7018 to E8018 is an essential variable under AWS D1.1:2025 Table 6.6, row covering filler metal classification. A PQR-supported WPS needs a new PQR test to cover the change. A prequalified WPS must be re-reviewed; E8018 may or may not be in the preapproved filler table for your specific joint, base metal, and process combination.

Hydrogen designators on structural SMAW WPS

When the WPS specifies a hydrogen-controlled process, the electrode's H-designator must be specified and maintained in storage. For SMAW, the low-hydrogen electrode conditioning requirements under AWS A5.1 and A5.5 apply:

• Electrodes arrive sealed in hermetic containers or moisture-resistant packaging
• Once opened, electrodes must be used within a specified time or returned to a holding oven at 250–300°F (120–150°C)
• If the exposure time is exceeded, electrodes must be baked at 700–800°F (370–425°C) per the applicable standard before use — not all electrodes can be baked repeatedly
• H4-designated electrodes have stricter limits than H8 or H16

This is different from FCAW wire handling — SMAW electrodes have established baking schedules; FCAW wire reconditioning depends on manufacturer authorization and is often not permitted.

Prequalification implications

AWS D1.1:2025 Clause 5 defines the conditions under which a WPS may be used without PQR testing (prequalified). Filler metal selection is one of the conditions:

• Only electrodes from the preapproved filler table may be used on prequalified WPS
• The electrode must match the base metal grouping — a prequalified WPS on A572 Grade 50 cannot arbitrarily use an electrode from a different strength group
• The heat input and position restrictions in Clause 5 still apply regardless of electrode choice

For prequalified WPS development under AWS D1.1:2025, the filler metal table is one of the first places to check when building a new procedure. Selecting an electrode outside the preapproved list forces the WPS to be PQR-supported — which means test plates, mechanical tests, and qualification costs.

Practical summary: which electrode for what

Electrode selection is not just a process decision — it drives WPS category (prequalified vs. PQR-supported), storage and handling requirements, and the preheat requirements that follow from the base metal's hydrogen sensitivity. Getting this right at WPS development time costs far less than requalifying procedures after an audit or, worse, after a weld failure.

For shops managing SMAW WPS libraries across multiple base metals and strength levels, a software platform that tracks electrode classification, H-designator, and prequalification status alongside the WPS and PQR records reduces the risk of using the wrong electrode on the wrong procedure. See our pricing page for how the WPS tool handles filler metal documentation.

Rule library based on AWS D1.1:2025; verify against your governing edition.