Lincoln Electric Innershield® NS-3M is a self-shielded, flux-cored arc welding wire engineered for the highest available deposition rates among all Innershield electrodes. Classified per AWS A5.20 / A5.36: E70T-4 / E70T4-AZ-CS3, NS-3M is designed specifically for single or multiple-pass welding on carbon steel in applications without impact strength requirements. Its E70T-4 chemistry delivers melt-off rates up to 14.8 lb/hr at 240 in/min on 5/64 in diameter, making it the productivity leader for high-speed flat and horizontal production welding. NS-3M also provides exceptional resistance to hydrogen cracking and porosity on steel containing sulfur or other surface contaminants — a significant advantage when welding structural steel that has not been ideally prepared.
| Parameter | Value |
|---|---|
| AWS Classification | E70T-4 / E70T4-AZ-CS3 (AWS A5.20 / A5.36) |
| CWB Classification | CSA W48 E490T4-AZ-CS3-H16 |
| ISO Classification | ISO 17632-A: T 38 Z V N 3 |
| Available Diameters | 5/64 in (2.0 mm), 0.120 in (3.0 mm) |
| Shielding Gas | None — self-shielded (FCAW-S) |
| Polarity | DCEP (DC electrode positive) |
| Welding Position | Flat (1G / 1F) and Horizontal (2G / 2F) |
| Tensile Strength (required AWS E70T-4) | 480–660 MPa (70–95 ksi) |
| Yield Strength (typical) | 410 MPa (59 ksi) as-welded |
| Tensile Strength (typical) | 570–640 MPa (82–93 ksi) as-welded |
| Elongation (typical) | 23 % in 2 in |
| Electrode Stick-Out (CTWD) | 54 mm (2-1/4 in) typical |
| Deposition Rate (5/64 at 200 in/min) | 4.6 kg/hr (10.1 lb/hr) |
| Deposition Rate (5/64 at 240 in/min) | 5.5 kg/hr (12.1 lb/hr) |
NS-3M's E70T-4 rating per AWS A5.20 designates a self-shielded electrode with no specified impact toughness requirements, intended for maximum deposition productivity. Its unique tolerance for sulfur-contaminated steel makes it especially valuable in:
- Steel service center processing lines — automated welding of hot-rolled structural shapes where mill scale and sulfur content vary
- High-production fabrication shops — continuous fillet welds on beams, girders, and built-up sections where throughput is the primary driver
- Construction site welding — no gas cylinder logistics; tolerates field conditions including light contamination on joint surfaces
- Shipbuilding and barge fabrication — flat and horizontal fillet welds on large structural panels in open environments
- Railroad car and heavy transport manufacturing — floor pans, cross-members, and bracket attachments on thick-section carbon steel
NS-3M uses DCEP polarity — unlike NR-311 which uses DCEN — and achieves its extraordinary deposition rates through a highly efficient open-arc flux system. The aluminum-bearing flux chemistry (typical Al content 1.3–1.5 %) provides robust deaeration of the weld pool, preventing the porosity and cracking that would occur when welding steel containing elevated sulfur (S > 0.05 %) or other contaminants. This makes NS-3M the preferred choice in applications where steel quality or surface preparation is variable.
At 5/64 in diameter with a 2-1/4 in CTWD, NS-3M supports wire feed speeds from 200 to 240 in/min at 280–315 amps. These currents produce deposition rates of 10–12 lb/hr at 82–83 % efficiency — matching or exceeding many gas-shielded FCAW-G wires while requiring no shielding gas infrastructure. Per Lincoln Electric product data, NS-3M is recommended for single or multiple-pass welding on carbon and some low-alloy steels in applications without impact strength requirements.
| Diameter | Polarity | CTWD | WFS (in/min) | Voltage (V) | Current (A) | Deposition (lb/hr) | Efficiency (%) |
|---|---|---|---|---|---|---|---|
| 5/64 in (2.0 mm) | DCEP | 2-1/4 in (54 mm) | 200 | 29–31 | 280 | 10.1 | 83 |
| 5/64 in (2.0 mm) | DCEP | 2-1/4 in (54 mm) | 240 | 30–32 | 315 | 12.1 | 82 |
NS-3M is classified as E70T-4 per AWS A5.20 and E70T4-AZ-CS3 per AWS A5.36. The T-4 designation is a self-shielded electrode engineered for maximum deposition in flat and horizontal positions, with no specified Charpy V-Notch impact toughness requirement.
NS-3M uses DCEP (DC Electrode Positive) — also called reverse polarity. This is notably different from NR-311 (which uses DCEN). Connect the gun lead to the positive terminal and work clamp to the negative terminal. Verify polarity before running any Innershield electrode, as incorrect polarity causes an unstable arc and defective welds.
Both are high-deposition, flat/horizontal, self-shielded FCAW-S wires, but they differ in polarity and chemistry. NR-311 uses DCEN and carries an E70T-7 classification. NS-3M uses DCEP and carries an E70T-4 classification. NS-3M delivers slightly higher deposition rates and superior resistance to porosity on sulfur-contaminated steel due to its higher aluminum content. Neither wire has specified CVN impact toughness. Always verify polarity on your machine before switching between these two products.
Yes — NS-3M is suitable for both single and multiple-pass welding on carbon steel. It is recommended for welding 1/8 in (3.2 mm) and thicker material. Inter-pass temperature should be managed according to the applicable code (typically 450–500 °F maximum for carbon steel without special requirements). Do not use NS-3M where CVN impact toughness properties are specified.
NS-3M's flux core contains elevated aluminum (1.3–1.5 % typical in the weld deposit), which acts as a powerful deoxidizer and desulfurizer. Aluminum reacts preferentially with oxygen and sulfur in the weld pool, preventing the formation of gas pockets (porosity) that would otherwise occur when welding steels with high S content or surface contamination. This is why Lincoln Electric recommends NS-3M specifically for steel containing sulfur or contaminants.
Browse the full welding wire collection or compare to Innershield NR-311 (E70T-7, DCEN) for standard high-deposition flat/horizontal work, or Outershield 71 Elite when a gas-shielded FCAW-G option is preferred.