Lincoln Electric SuperArc® LA-90 is a high-strength low-alloy (HSLA) solid MIG wire classified AWS A5.28 ER90S-G, engineered for welding high-strength steels where standard ER70S-6 wire undermatches base metal tensile requirements. This listing is the 0.045" (1.14 mm) diameter, 44 lb steel spool (EDS30776) — the production format for structural and heavy-equipment fabrication on HSLA and quenched-and-tempered (Q&T) steels requiring minimum 90 ksi weld metal tensile strength.
SuperArc LA-90 deposits weld metal with minimum 90 ksi tensile and 78 ksi yield strength. It bridges the gap between standard ER70S-6 (70 ksi class) and ultra-high-strength ER100S-G or ER110S-G wires. WeldingMart is an authorized Lincoln Electric distributor. Browse all welding wire.
| Part Number | EDS30776 |
|---|---|
| AWS Classification | AWS A5.28 ER90S-G |
| Wire Type | Solid, High-Strength Low-Alloy (HSLA) MIG Wire |
| Wire Diameter | 0.045 in (1.14 mm) |
| Spool Weight | 44 lb steel spool |
| Base Metal | HSLA and Q&T steels: ASTM A514, A572 Gr. 65, A709 Gr. 70W, A852, HY-80, HY-100 |
| Min. Tensile Strength | 620 MPa (90 ksi) as-welded |
| Min. Yield Strength | 537 MPa (78 ksi) as-welded |
| Shielding Gas | 75% Ar / 25% CO₂ (C25) or 90% Ar / 10% CO₂ (C10); flow 30–50 CFH |
| Polarity | DCEP (DC Electrode Positive / DC+) |
| Transfer Modes | Short-circuit, spray, pulsed spray |
| Welding Positions | All positions |
| Typical Applications | ASTM A514, A709, A852, HY-80/100 steel; heavy construction equipment; military/defense; pressure vessels requiring 90 ksi class filler metal |
Source: Lincoln Electric SuperArc LA-90 product page
- High-strength structural steel (A572 Gr. 65, A852): LA-90 is appropriate for base metals with minimum yield strength above 65 ksi where ER70S-6 would be undermatched per code requirements. Applicable to ASTM A709 Gr. 70W and 100W weathering bridge steel where weld metal strength must equal or exceed base metal yield.
- Heavy construction and mining equipment: Boom arms, lift structures, excavator buckets, crane booms, and chassis components fabricated from T-1 (A514) and other Q&T steels. The 44 lb spool minimizes spool changes during long production runs on high-strength fabrication.
- Military and defense fabrication: HY-80 and HY-100 steel applications in armored vehicle hulls, defense marine vessel construction, and naval ship fabrication where matching wire strength and certified mechanical properties are mandatory.
- Pressure vessel fabrication: ASME Section IX-qualified applications where a higher-strength deposit than ER70S-class can provide is required by design specification or code.
- Pipeline and heavy industry: High-strength pipe joints and fittings where design or code specifies minimum 80 or 90 ksi class filler metal.
- Structural repair on HSLA equipment: Replacement and repair of worn or damaged HSLA components where undermatching with ER70S-6 is not permitted by engineering.
SuperArc LA-90 requires DCEP (DC+) polarity.
Gas selection: LA-90 performs best with argon-rich shielding gases that minimize heat input and maintain the alloy chemistry in the deposit:
- 75% Ar / 25% CO₂ (C25): Standard shop choice. Stable arc, acceptable spatter level. Well-suited for short-circuit and spray transfer on .045".
- 90% Ar / 10% CO₂ (C10): Preferred for spray and pulsed spray transfer. Lower spatter, slightly higher deposition efficiency. Preferred for robotic cells running LA-90 on HSLA structural components.
Preheat requirements: Always follow the preheat requirements per the applicable code (AWS D1.1 Table 3.2 or equivalent) for the base metal grade and thickness. High-strength Q&T steels typically require 150–250°F (65–121°C) minimum preheat. Interpass temperature control is also critical — check the steel manufacturer's data sheet for maximum interpass temperature limits (typically 400–600°F for HY-80/100).
| SuperArc L-56 (ER70S-6) | A36, A572 Gr. 50 mild and low-alloy steel. Minimum 70 ksi tensile. Standard choice for the vast majority of structural mild steel work. |
|---|---|
| SuperArc LA-90 (ER90S-G) — this listing | HSLA steel where yield > 65 ksi. A514, A572 Gr. 65, A852, HY-80, A709 Gr. 70W. Min 90 ksi tensile deposit. Use when ER70S-6 undermatches. |
| SuperArc LA-100 (ER100S-G) — ED031417 | A514, HY-100, and higher-strength Q&T steels requiring 100 ksi class deposit. Narrow application window; consult metallurgist for base metal / filler selection. |
- When do I need ER90S-G instead of ER70S-6?
- When your base metal's min yield exceeds ~65 ksi (A514, A572 Gr. 65, A852, HY-80, A709 Gr. 70W), or when your WPS requires matching/overmatching filler metal. Standard A36 / A572 Gr. 50 does NOT require LA-90.
- What shielding gas is required?
- 75% Ar / 25% CO₂ (C25) or 90% Ar / 10% CO₂ (C10). Argon-rich mixes are specified — 100% CO₂ is not recommended because it can degrade the deposited alloy chemistry and reduce strength.
- Does LA-90 require preheat?
- Yes — high-strength Q&T steels are susceptible to hydrogen cracking without preheat. Typical 150–250°F (65–121°C) minimum per AWS D1.1 Table 3.2 or steel manufacturer data. Never skip preheat on A514, HY-80, or similar base metals.
- Can I use LA-90 on A36 steel?
- Technically yes, but it is overmatched and more expensive than needed. Use SuperArc L-56 (ER70S-6) for A36 and standard A572 Gr. 50 structural steel.
- What is the difference between LA-90 and LA-100?
- LA-90 = 90 ksi class for A572 Gr. 65, HY-80, A514. LA-100 = 100 ksi class for HY-100 and higher-strength requirements. See SuperArc LA-100 .045" 33 lb.
Browse sibling wire PDPs: SuperArc L-56 ER70S-6 (standard mild steel) | SuperArc LA-100 .045" 33 lb (100 ksi class) | All Welding Wire
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