E7018 vs E6013: When to Use Each Electrode
E7018 is a low-hydrogen electrode with 70 ksi tensile strength, classified under AWS A5.1. E6013 is a rutile electrode with 60 ksi tensile strength. Under D1.1:2025 Table 5.11, switching from E6013 to E7018 on A36 steel drops your preheat from 150°F to 50°F above 3/4 inch thickness.
Side-by-Side Comparison
| Property | E7018 | E6013 |
|---|---|---|
| AWS Specification | A5.1 | A5.1 |
| Process | SMAW | SMAW |
| Minimum Tensile Strength | 70 ksi | 60 ksi |
| Coating Type | Iron-powder low-hydrogen | Rutile (high titania) |
| D1.1 Preheat Category (A36) | Category B | Category A |
| Preheat at 1 inch A36 | 50°F | 150°F |
| Oven Storage Required | Yes — 250°F minimum | No |
| Atmospheric Exposure Limit | 4 hours (Table 7.1) | No D1.1 limit |
| Typical Amperage (1/8 in.) | 90–160 A | 80–150 A |
| Table 5.7 Matching Group | Groups I and II | Group I only |
What the Classification Numbers Mean
Both electrodes follow the AWS A5.1 naming system. The E stands for electrode. The next two digits are the minimum tensile strength in ksi: 70 for E7018 and 60 for E6013. The last two digits identify the coating chemistry and usability.
The 18 in E7018 designates an iron-powder low-hydrogen coating. Low-hydrogen means the coating is formulated to deposit minimal diffusible hydrogen into the weld metal. The 13 in E6013 designates a rutile (high titania) coating, which produces a smooth arc and easy slag removal but deposits more hydrogen.
That hydrogen difference is the reason D1.1 assigns them to different preheat categories.
How Electrode Choice Changes Your Preheat
D1.1:2025 Table 5.11 groups welding processes and electrodes by hydrogen risk. E7018 falls under Category B (SMAW with low-hydrogen electrodes, alongside GMAW, FCAW, and SAW). E6013 falls under Category A (SMAW with other than low-hydrogen electrodes).
For A36 steel, the preheat difference between these categories is significant:
| Thickness (A36) | Cat A (E6013) °F | Cat B (E7018) °F | Difference |
|---|---|---|---|
| 1/8 to 3/4 in. incl. | 32* | 32* | 0°F |
| Over 3/4 thru 1-1/2 in. | 150 | 50 | 100°F |
| Over 1-1/2 thru 2-1/2 in. | 225 | 150 | 75°F |
| Over 2-1/2 in. | 300 | 225 | 75°F |
*Footnote a (Table 5.11): When the base metal temperature is below 32°F, the base metal shall be preheated to a minimum of 70°F and the minimum interpass temperature shall be maintained during welding.
Below 3/4 inch, the choice does not affect your preheat. Above 3/4 inch, E7018 saves you 75°F to 100°F of preheat on every joint.
Storage and Handling: The Real Shop Difference
E7018 requires infrastructure that E6013 does not. Per Clause 7.3.2.1, all low-hydrogen electrodes must be purchased in hermetically sealed containers or baked before use. After opening, they must be stored in ovens held at a minimum of 250°F. Table 7.1 limits atmospheric exposure to 4 hours for E70XX electrodes (Column A). Electrodes exposed longer than 4 hours must be baked at 500°F to 800°F for at least two hours per Clause 7.3.2.4. Electrodes that have been wet shall not be used. Rebaking is permitted only once.
E6013 has no D1.1 oven storage requirement. You can leave the box open on the bench and use them the next day. For small shops without rod ovens, this is a real operational consideration.
A structural steel shop running 1-inch A36 plate switches from E6013 to E7018. The electrode costs a few cents more per pound. The oven costs a few hundred dollars. But the preheat drops from 150°F to 50°F on every joint—less propane, less waiting, faster throughput. On a 50-joint job, the preheat savings alone pay for the oven in the first week.
Strength and Matching Requirements
Table 5.7 in D1.1:2025 defines which electrodes provide matching filler metal strength for each base metal group. E7018 matches both Group I and Group II steels. Group I includes A36, A53 Grade B, A500, A501, A516, and other common structural steels. Group II includes A572 Grades 42 through 65, A588, and A709.
E6013 matches Group I steels only (E60XX classification). For Group II steels, the 60 ksi tensile strength of E6013 does not meet the matching strength requirement. If your joint connects A36 to A572 Grade 50, E7018 is the correct choice for matching filler metal per Table 5.7.
Per Clause 5.6.1, see Table 4.3 or Table 10.2 to determine the filler metal strength requirements for matching or undermatching base metal strength. Overmatching up to 10 ksi above the Table 5.7 requirement is permitted per Clause 5.6.3.
When E6013 Is the Right Call
E6013 is not a second-rate electrode. It has specific advantages that make it the better choice in certain situations:
Thin material and sheet metal: E6013 runs smoothly at lower amperages with less penetration, making it easier to control on material under 3/16 inch where burn-through is a risk. At these thicknesses, both electrodes require identical preheat (32°F).
Appearance-critical welds: The rutile coating produces a fine-rippled bead with minimal spatter and easy slag removal. For welds that will be visible and not painted, E6013 gives a cleaner surface finish.
Non-structural connections on 3/4-inch-and-under material: If your application does not require matching strength to Group II steels and the material is 3/4 inch or under, E6013 is code-compliant for D1.1 prequalified joints on Group I steels, with no preheat penalty and no oven requirement.
Shops without rod ovens: E6013 requires no oven storage. For maintenance welding, field repairs on light structures, or small fabrication shops welding thin A36, this removes an equipment requirement entirely.
Welding Position and Arc Behavior
Both electrodes are classified for all positions per their A5.1 designations. In practice, they behave differently. E7018 produces a smooth, quiet arc with heavier slag. It runs well in flat and horizontal positions but can be more challenging out of position for newer welders because the slag is fluid. The iron-powder coating provides higher deposition rates in flat position.
E6013 has a softer, more stable arc at lower amperages. It is often recommended as a learning electrode because it is more forgiving of arc length variation. The slag peels easily, even on tack welds. This makes it practical for short welds, tack welds, and situations where slag removal between passes is critical.
Frequently Asked Questions
E6013 is prequalified under D1.1 for Group I steels like A36, but it falls under Category A in Table 5.11. That means higher preheat requirements above 3/4 inch thickness. For structural connections on thicker material, most fabricators use E7018 because it provides both higher strength (70 ksi vs 60 ksi) and lower preheat requirements through Category B classification.
E7018 has a low-hydrogen coating that absorbs moisture from the air. Clause 7.3.2.1 requires low-hydrogen electrodes to be stored in ovens at a minimum of 250°F after opening the hermetically sealed container. Table 7.1 limits atmospheric exposure to 4 hours for E70XX electrodes. If exposed longer, they must be baked at 500°F to 800°F per Clause 7.3.2.4. E6013 has no oven storage requirement because its rutile coating is not moisture-sensitive in the same way.
In the AWS A5.1 classification system, the last two digits indicate the coating type and welding position. The 18 in E7018 designates an iron-powder low-hydrogen coating suitable for all positions. The 13 in E6013 designates a rutile (high titania) coating suitable for all positions. The first two digits after E indicate minimum tensile strength in ksi: 70 for E7018 and 60 for E6013.
For A36 steel over 3/4 through 1-1/2 inch, Table 5.11 requires 150°F preheat with E6013 (Category A) but only 50°F with E7018 (Category B). That is a 100°F difference from electrode choice alone. At 1-1/2 through 2-1/2 inch, the gap narrows to 75°F: 225°F for Category A versus 150°F for Category B. Above 2-1/2 inch, it is 300°F versus 225°F.
E7018 is the standard choice for structural work because of its higher tensile strength, lower hydrogen deposit, and lower preheat requirements. But E6013 has legitimate uses: it produces a smooth arc with less spatter, works well on thin sheet metal and light fabrication, runs on smaller machines, and requires no oven storage. For non-structural work on material 3/4 inch and under, where both categories require only 32°F preheat, E6013 is a practical and code-compliant option.