Lincoln Excalibur 7028 is a high-deposition low-hydrogen E7028 welding rod designed for maximum productivity flat and horizontal fillet welds on mild carbon steel. The E7028 classification features a heavy iron-powder, low-hydrogen flux covering that delivers the highest deposition efficiency of any AWS A5.1 electrode — up to 145 % deposition efficiency — making Excalibur 7028 the preferred E7028 welding rod for high-volume flat and horizontal welding production on structural steel fabrication lines, offshore platform construction, and pressure vessel shops where fillet weld volume is critical.
Excalibur 7028 is Lincoln Electric's high-productivity E7028 low-hydrogen iron-powder SMAW electrode. The AWS classification E7028 decodes as: "E" = electrode; "70" = 72,000 psi minimum tensile strength; "2" = flat and horizontal fillet positions only (not all-position); "8" = low-hydrogen iron-powder flux covering, DCEP or AC. The position limitation to flat (F) and horizontal (H) fillet is deliberate: E7028 carries significantly more iron powder in its flux coating than E7018 — this thick covering with high iron-powder loading produces extremely fast deposition rates and a very wide, flat bead profile, but the thick slag must freeze flat. Running E7028 in vertical or overhead positions is not possible — the flux geometry and slag fluidity prevent it. This is the fundamental trade-off: you exchange positional flexibility for maximum deposition rate in flat and horizontal work. For production shops where 80–90 % of welding is flat or horizontal fillet welds, this trade-off is highly favorable. Excalibur 7028 carries Lincoln's H4R hydrogen designation — diffusible hydrogen ≤ 4 mL/100g — providing the same hydrogen control as E7018-H4R in a dramatically more productive flat/horizontal electrode.
| Property | Value |
|---|---|
| AWS Classification | E7028 |
| Standard | AWS A5.1/A5.1M |
| H-Designation | H4R (≤ 4 mL/100g diffusible H2) |
| Tensile Strength (min.) | 72,000 psi (496 MPa) |
| Yield Strength (min.) | 60,000 psi (414 MPa) |
| Elongation (min.) | 22% |
| Deposition Efficiency | ~145% (highest in AWS A5.1) |
| Flux Type | Low-hydrogen iron-powder (heavy coating) |
| Current | AC, DCEP |
| Positions | Flat (1F) and Horizontal Fillet (2F) only |
| Diameters | 3/16, 7/32, 1/4 in (large diameters typical) |
E7028 is rated at 22 % elongation — higher than E7018 at 22 % but both reflect good ductility from the low-hydrogen iron-powder chemistry. The H4R designation is critical: unlike non-low-hydrogen rods (E6013, E7014), E7028 must be stored in a 250–300 °F holding oven after the container is opened to maintain ≤ 4 mL/100g diffusible hydrogen. This storage requirement is identical to E7018 and E8018 low-hydrogen rods.
- High-volume flat fillet welds on structural steel fabrication lines — connecting beam flanges, gussets, base plates, and stiffeners where F and H positions dominate.
- Offshore oil and gas platform jackets and topsides — massive fillet weld volumes on tubular and plate structures welded in flat position.
- Pressure vessel and heat exchanger shell welds — circumferential seam welds in the flat position on vessel rotating positioners.
- Bridge fabrication shop welds — high-volume fillet welds on girder flanges and web-to-flange connections in positioner-assisted flat position.
- Heavy machinery and crane fabrication — fillet welds on structural frames and booms where flat-position fixturing is practical.
- Production shops that use weld positioners — E7028 is most productive when work is rotated to flat or horizontal using jigs and positioners.
| Diameter | Amperage Range (DCEP) | Typical Deposition Rate |
|---|---|---|
| 3/16 in (4.8 mm) | 225–310 A | ~10 lb/hr |
| 7/32 in (5.6 mm) | 280–375 A | ~13 lb/hr |
| 1/4 in (6.4 mm) | 350–450 A | ~16 lb/hr |
Flat fillet technique: Hold electrode at 45° bisecting angle to the joint, 0–15° drag angle. Use straight travel with no weave — the wide iron-powder arc fills the joint without weaving. Keep arc length short (1× core or less) to maintain maximum deposition and minimum spatter. The self-releasing slag lifts clean on flat surfaces for fast production pace.
Horizontal fillet: Angle slightly toward the vertical plate (50–55° from horizontal) to prevent sagging of the weld metal. Travel speed controls leg size — faster travel for smaller legs, slower for larger.
Low-hydrogen oven protocol: E7028 is a low-hydrogen electrode. Opened containers must be kept in a 250–300 °F holding oven. Do not leave E7028 electrodes on the shop floor or in the electrode holder between passes for extended periods in humid environments.
E7028 requires the same storage protocol as E7018 low-hydrogen electrodes:
- Sealed containers: Lincoln's hermetically sealed canisters maintain H4R condition in storage. Use from sealed can within 4–9 hours of opening in ambient conditions per AWS D1.1 Table 4.7 holding limits.
- Holding oven required: Once opened, keep E7028 in a 250–300 °F holding oven between uses. This is mandatory for H4R compliance.
- Re-drying if needed: If exposed to moisture, dry at 700–800 °F for 1 hour (same as E7018 redrying per AWS D1.1). This is a high temperature dry — do not confuse with the 250 °F reconditioning used for non-low-hydrogen rods.
- Tracking exposure time: For code-required H4R welds, track the cumulative time electrodes have been outside the oven. AWS D1.1 limits exposure time per classification and environment humidity before mandatory redrying.
E7028 is suitable for mild steel and low-alloy carbon steel:
- ASTM A36, A572 Grades 42–65
- ASTM A516 Grades 55–70 (pressure vessel)
- ASTM A709 Grade 50 (bridge plate)
- API 2W Grade 50 offshore plate
E7028 is used exclusively for flat and horizontal fillet and lap joints, horizontal groove welds, and flat position butt joints. It is not used for any vertical, overhead, or pipe welding position.
Q: Why is E7028 limited to flat and horizontal positions only?
E7028 uses a very heavy iron-powder flux coating that produces a thick, fluid slag. This slag must freeze flat to prevent rundown. In vertical or overhead positions, the fluid slag would run out of the joint before the weld metal freezes, causing severe defects. E7018, with a thinner iron-powder coating and faster-freezing slag, is the appropriate choice for all-position low-hydrogen welding.
Q: What is deposition efficiency and why does it matter?
Deposition efficiency is the percentage of electrode weight (excluding stub loss) that is deposited as weld metal. E7018 achieves ~115 % (with iron powder adding weight); E7028 achieves ~145 %. On a shop welding 1,000 lb of weld metal per week, E7028 reduces electrode consumption by roughly 20 % compared to E7018 for the same weld volume — significant cost savings in production.
Q: How do I store E7028 to maintain the H4R rating?
Keep in a 250–300 °F holding oven once the sealed container is opened. Never leave E7028 on the shop floor overnight. AWS D1.1 Table 4.7 permits limited exposure time outside the oven (2–4 hours depending on environment humidity) before mandatory redrying at 700–800 °F for 1 hour.
Q: Can I use E7028 for structural welding per AWS D1.1?
Yes. E7028 H4R is listed in AWS D1.1 Table 4.5 as an approved filler for prequalified WPS and meets the Low Hydrogen requirement for Category F and H weld positions. It is fully approved for structural welding in flat and horizontal positions. For all-position structural work, use E7018.
Q: What is the largest single-pass fillet weld I can make with E7028?
With 7/32 in or 1/4 in E7028, a single flat pass can make a 3/8 in to 1/2 in leg fillet weld. For legs over 1/2 in, multiple passes are required. E7028's high deposition rate means each pass deposits maximum weld metal per arc-on time.
Q: Is E7028 better than SAW (submerged arc) for flat fillet welds?
SAW (submerged arc welding) achieves higher deposition rates (30–60 lb/hr vs. 10–16 lb/hr for E7028) but requires fixed setups, flux handling equipment, and is impractical for complex joint configurations. E7028 provides the highest manual SMAW deposition rate without the fixturing requirement of SAW, making it the best choice for shops that can't justify SAW equipment or need flexibility to move the electrode around the joint.
Q: How does E7028 compare to E7018 in the flat position?
In flat and horizontal fillet positions, E7028 outperforms E7018 in deposition rate (~145 % vs. ~115 %) and operator-perceived ease — the wide, self-leveling bead requires less operator technique to produce a consistent flat fillet. E7018 is used when you also need vertical and overhead positions; E7028 is strictly more productive in flat/horizontal production environments.
The E7028 welding rod's high deposition efficiency (approximately 145%) results from the large iron-powder loading in the flux coating — iron powder is melted and deposited as weld metal along with the core wire, dramatically increasing the amount of weld metal deposited per unit of core wire consumed. For structural fabrication shops tracking electrode costs, E7028 provides approximately 25% more weld metal per pound of electrode purchased compared to E7018, and up to 40% more compared to bare E7016 or E7015 electrodes. This cost advantage is most pronounced in high-volume flat and horizontal fillet weld applications — beam-to-column connections, gusset plates, base plate fillet welds, and vessel seam welds where every weld can be made in the flat (1F, 1G) or horizontal fillet (2F) position using positioners or purpose-built fixtures. E7028 is specified in AWS D1.1 Table 4.5 as an approved filler metal for flat and horizontal positions on Group I and II steels. Its H4R hydrogen designation matches the low-hydrogen requirement for high-restraint, thick-section structural joints. When planning production welding operations with E7028, calculate the electrode burn-off rate at the specific amperage and duty cycle to determine electrode quantities for the production run — Lincoln's published technical data provides burn-off rate curves for all available E7028 diameters at certified amperage settings.