Lincoln Electric Innershield® NR-311 is a self-shielded, flux-cored arc welding (FCAW-S) wire designed for the highest possible deposition rates in flat and horizontal positions without requiring external shielding gas. Classified per AWS A5.20 / A5.36: E70T-7 / E70T7-AZ-CS3, NR-311 runs on DC electrode negative (DCEN) — the opposite polarity from solid MIG wire — and delivers an open-arc, high-current process capable of melt-off rates exceeding 13 lb/hr. Its self-contained flux chemistry shields the arc from atmosphere and produces an easily removed slag with excellent bead shape in fillet, lap, and butt joints. NR-311 is the productivity choice for shops and field crews that cannot use gas cylinders outdoors or in windy conditions.
| Parameter | Value |
|---|---|
| AWS Classification | E70T-7 / E70T7-AZ-CS3 (AWS A5.20 / A5.36) |
| Available Diameters | 5/64 in (2.0 mm), 3/32 in (2.4 mm), 7/64 in (2.8 mm) |
| Shielding Gas | None — self-shielded (FCAW-S) |
| Polarity | DCEN (DC electrode negative) |
| Welding Position | Flat (1G / 1F) and Horizontal (2G / 2F) |
| Tensile Strength (required) | 480 MPa (70 ksi) minimum per AWS A5.20 |
| Tensile Strength (typical) | 590 MPa (86 ksi) as-welded |
| Yield Strength (typical) | 430 MPa (62 ksi) as-welded |
| Elongation (typical) | 25 % in 2 in |
| Electrode Stick-Out (ESO) | 1–1/2 in (38 mm) typical |
| Deposition Rate (5/64 at 200 in/min) | ~4.5 kg/hr (9.9 lb/hr) |
| Deposition Rate (5/64 at 240 in/min) | ~5.5 kg/hr (12.1 lb/hr) |
| Minimum Plate Thickness | 3.2 mm (1/8 in) |
NR-311's E70T-7 classification per AWS A5.20 places it in the high-deposition, flat/horizontal category without required impact toughness — making it the right choice when deposition rate and productivity matter more than low-temperature CVN performance.
- Structural steel fabrication — fillet welds on columns, beams, base plates, and bracket connections on 1/8 in and heavier steel
- Field construction and bridge work — outdoor welding where wind would blow away shielding gas; no cylinder handling required
- General fabrication and assembly — high-speed lap welds, T-joints, and butt welds on mild and some low-alloy steels in production environments
- Heavy equipment repair — bucket teeth attachments, lifting lugs, and structural repairs where fast deposition on thick sections is required
- Shipbuilding and barge construction — flat and horizontal stiffener welds where gas shielding is impractical
Innershield NR-311 uses a self-shielding flux system: as the electrode melts, the flux core decomposes to generate protective shielding gases and forms a slag blanket that protects the solidifying weld metal. This makes NR-311 uniquely suited for outdoor and field applications where wind, drafts, or limited accessibility make gas-shielded processes impractical. The open-arc characteristic and DCEN polarity allow very high wire feed speeds — the 5/64 in diameter supports wire feed speeds from 100 to 240 in/min, corresponding to currents from 170 to 295 amps.
Because NR-311 is rated for flat and horizontal positions only, it should not be used for vertical or overhead welding. For out-of-position self-shielded work, see Innershield NR-211-MP (E71T-11, all-position). NR-311 does not have specified CVN impact toughness requirements — for structural seismic applications requiring notch toughness, see the NR-311 Ni variant.
| Diameter | Polarity | ESO | WFS (in/min) | Voltage (V) | Current (A) | Deposition (lb/hr) |
|---|---|---|---|---|---|---|
| 5/64 in (2.0 mm) | DCEN | 1-1/2 in (38 mm) | 100 | 21–23 | 170 | 5.5 |
| 5/64 in (2.0 mm) | DCEN | 1-1/2 in (38 mm) | 160 | 25–27 | 235 | 8.8 |
| 5/64 in (2.0 mm) | DCEN | 1-1/2 in (38 mm) | 200 | 26–28 | 270 | 11.0 |
| 5/64 in (2.0 mm) | DCEN | 1-1/2 in (38 mm) | 240 | 27–29 | 295 | 13.3 |
| 3/32 in (2.4 mm) | DCEN | 1-3/4 in (44 mm) | 80 | 26–28 | 275 | ~12 |
| 3/32 in (2.4 mm) | DCEN | 1-3/4 in (44 mm) | 100 | 28–30 | 330 | ~15 |
Innershield NR-311 is classified as E70T-7 per AWS A5.20 and E70T7-AZ-CS3 per AWS A5.36. The "T-7" classification indicates a self-shielded, flat/horizontal electrode intended for high deposition rates without specified CVN impact toughness requirements. Lincoln Electric also lists it as compliant with AWS D1.8 seismic supplement requirements.
No. Innershield NR-311 is a self-shielded (FCAW-S) wire. The flux inside the tubular electrode generates its own shielding atmosphere when the arc melts the wire. No external gas cylinder, regulator, or hose is required — making it ideal for outdoor, field, and remote welding situations where wind or lack of infrastructure makes gas shielding impractical.
NR-311 runs on DCEN (DC Electrode Negative) — also called straight polarity. This is the opposite of solid MIG wire (which uses DCEP). Ensure your wire feeder and power source are set to DC−. Running an Innershield wire on DCEP will result in an erratic arc, excessive spatter, and poor penetration.
NR-311 is rated for flat (1G/1F) and horizontal (2G/2F) positions only. Its high-deposition, fast-freeze slag system is optimized for these positions and should not be used in vertical or overhead orientations. For all-position self-shielded FCAW, choose Innershield NR-211-MP (E71T-11) or NR-232 (E71T-8).
The recommended electrode stick-out for the 5/64 in diameter NR-311 is 1-1/2 in (38 mm), and for 3/32 in it is 1-3/4 in (44 mm). This is significantly longer than solid MIG wire stick-out (which is typically 1/2–3/4 in). The extended stick-out is critical to achieving stable arc performance with Innershield electrodes — too short a stick-out will result in a cold, erratic arc.
Browse the complete welding wire collection or compare with Innershield NS-3M (E70T-4) for even higher deposition rates, or Innershield NR-211-MP for all-position self-shielded work.