MIG wire by material specifications
MIG (Metal Inert Gas) welding wire comes in the form of a continuous consumable electrode and constitutes the filler material that, upon melting by an electric arc protected by inert or active gas, joins the workpieces. Wire specifications — chemical composition, diameter, and mechanical properties — determine its suitability for each base material and application. Among the most widely used wires in the industry are ER70S-6 for carbon steels, ER308L for austenitic stainless steels, and ER4043 for aluminum alloys. This technical guide brings together the essential data for these three MIG wires and provides verified operating parameters for their correct selection and application.
Purpose and applications
Section titled “Purpose and applications”ER70S-6 wire is a solid electrode for welding carbon steels with tensile strength requirements up to 70 ksi (483 MPa). It contains elevated levels of manganese and silicon that improve deoxidation and allow welding on surfaces with light rust or mill scale. It is the preferred choice in general fabrication, metal structures, automotive bodies, pressure vessels, and pipelines up to API 5L X52 grade.
ER308L wire is designed for welding 18Cr-8Ni type stainless steels, such as grades 304, 304L, 308, and 308L. Its low carbon content (max 0.03%) reduces the risk of chromium carbide precipitation and provides resistance to intergranular corrosion in the as-welded condition. It is used in equipment for the chemical, food, and pharmaceutical industries, and in the manufacture of cryogenic piping and tanks.
ER4043 wire is an aluminum alloy with 5% silicon that lowers the melting temperature, improves weld pool fluidity, and minimizes hot cracking. It is used to weld aluminum alloys of series 3003, 6061, 6063, and 5052, as well as for dissimilar joints between aluminum and some coated steels. It is common in the automotive, marine, heat exchanger, and lightweight structure industries.
Chemical composition
Section titled “Chemical composition”| Element | ER70S‑6 (% weight) | ER308L (% weight) | ER4043 (% weight) |
|---|---|---|---|
| Carbon (C) | 0,06 – 0,15 | 0,03 max. | — |
| Manganese (Mn) | 1,40 – 1,85 | 1,0 – 2,5 | 0,05 max. |
| Silicon (Si) | 0,80 – 1,15 | 0,30 – 0,65 | 4,5 – 6,0 |
| Phosphorus (P) | 0,025 max. | 0,03 max. | — |
| Sulfur (S) | 0,035 max. | 0,03 max. | — |
| Chromium (Cr) | 0,15 max. | 19,5 – 22,0 | — |
| Nickel (Ni) | 0,15 max. | 9,0 – 11,0 | — |
| Iron (Fe) | Balance | Balance | 0,8 max. |
| Copper (Cu) | 0,50 max. | 0,75 max. | 0,30 max. |
| Aluminum (Al) | — | — | Balance |
| Others | Mo 0,15 max. | Mo 0,75 max. | Zn 0,10 max.; Ti 0,20 max. |
Mechanical properties
Section titled “Mechanical properties”The values below are typical for MIG welding with suitable shielding gas (Ar/CO₂ or Ar/He depending on material) and without post-weld heat treatment, unless otherwise indicated.
| Property | ER70S‑6 | ER308L | ER4043 |
|---|---|---|---|
| Tensile strength | 483 MPa min. / 70 ksi min. | 550 MPa typical / 80 ksi typical | 165 MPa typical / 24 ksi typical |
| Yield strength (0,2 %) | 400 MPa typical / 58 ksi typical | 380 MPa typical / 55 ksi typical | 70 MPa typical / 10 ksi typical |
| Elongation (Lo=50 mm) | 22 % min. | 35 % typical | 12 % typical |
| Charpy V-notch impact energy | 27 J at –30 °C / 20 ft·lbf at –22 °F | 50 J at –196 °C / 37 ft·lbf at –321 °F | — |
Welding parameters
Section titled “Welding parameters”The following table presents parameter ranges for common wire diameters of ER70S-6, ER308L, and ER4043 in the flat position, using short circuit or pulsed spray transfer as applicable. The wire feed speed (WFS) values are indicative and depend on the average working amperage.
| Wire | Diameter metric / imperial | Voltage (V) | Amperage (A) | Feed speed (m/min / in/min) | Shielding gas |
|---|---|---|---|---|---|
| ER70S‑6 | 0,8 mm / 0.030 in | 16 – 22 | 60 – 180 | 2,5 – 8,5 / 98 – 335 | 75 % Ar – 25 % CO₂ |
| ER70S‑6 | 1,0 mm / 0.040 in | 18 – 26 | 100 – 250 | 2,0 – 7,0 / 79 – 276 | 75 % Ar – 25 % CO₂ |
| ER70S‑6 | 1,2 mm / 0.045 in | 20 – 30 | 150 – 350 | 2,5 – 9,0 / 98 – 354 | 75 % Ar – 25 % CO₂ |
| ER308L | 0,8 mm / 0.030 in | 15 – 20 | 50 – 150 | 2,0 – 7,0 / 79 – 276 | 98 % Ar – 2 % CO₂ |
| ER308L | 1,0 mm / 0.040 in | 16 – 22 | 80 – 220 | 2,5 – 8,0 / 98 – 315 | 98 % Ar – 2 % CO₂ |
| ER308L | 1,2 mm / 0.045 in | 18 – 26 | 120 – 300 | 3,0 – 9,0 / 118 – 354 | 98 % Ar – 2 % CO₂ |
| ER4043 | 1,0 mm / 0.040 in | 18 – 24 | 90 – 200 | 3,5 – 9,0 / 138 – 354 | 100 % Ar |
| ER4043 | 1,2 mm / 0.045 in | 20 – 27 | 120 – 280 | 4,0 – 11,0 / 157 – 433 | 100 % Ar |
| ER4043 | 1,6 mm / 1/16 in | 22 – 30 | 160 – 350 | 3,5 – 9,5 / 138 – 374 | 100 % Ar |
Advantages and limitations
Section titled “Advantages and limitations”ER70S‑6
- Advantages: excellent wetting and smooth bead profile; tolerant to light surface contamination; supports all positions with suitable parameters; wide availability and relatively low cost.
- Limitations: not suitable for steels with high sulfur or phosphorus content without additional preparation; requires CO₂ gas mixture for optimum penetration; not resistant to atmospheric corrosion without coating.
ER308L
- Advantages: very good resistance to intergranular corrosion in as-welded condition; excellent low-temperature toughness; clean surface finish with minimal spatter when using argon-rich gas.
- Limitations: higher cost than carbon steel wires; sensitive to joint cleanliness (grease, oxides); short circuit transfer can generate excessive spatter if inductance is not adjusted.
ER4043
- Advantages: high resistance to hot cracking; good weld pool fluidity and bright bead; lower melting point than base metal reduces distortion; suitable for dissimilar aluminum joints.
- Limitations: mechanical properties inferior to magnesium-bearing fillers (e.g., ER5356) in strength and ductility; not suitable for subsequent decorative anodizing due to color change; not recommended for continuous service above 150 °C / 302 °F.
Selection guide
Section titled “Selection guide”For carbon and low-alloy steels with strength requirements up to 483 MPa / 70 ksi and ease of shop use, select ER70S‑6. Use diameters of 0.8–1.0–1.2 mm according to part thickness and position. The 75Ar/25CO₂ mixture provides a balance between penetration and arc stability.
For austenitic stainless steels type 304/304L, the direct choice is ER308L. If the part will operate at cryogenic temperatures or in corrosive environments, confirm that the delta ferrite content in the deposit is between 4% and 10% to avoid cracking. 98Ar/2CO₂ gas minimizes surface oxidation.
For wrought and cast aluminum alloys compatible with silicon (3xxx, 6xxx series), choose ER4043. Ensure a pure argon (100%) flow rate of 14–20 L/min / 30–42 ft³/h and use a push-pull system or spool gun for stable feeding. If maximum mechanical strength is required or welding 5xxx series parts, consider switching to ER5356.
Parameter table by material
Section titled “Parameter table by material”The following table compiles the reference parameters for the welder based on the most common base materials for each of the described MIG wires.
| Base material | Recommended wire | Typical diameter (mm / in) | Voltage (V) | Amperage (A) | Feed speed (m/min / in/min) | Gas |
|---|---|---|---|---|---|---|
| Structural steel S235‑S355 | ER70S‑6 | 1,0 mm / 0.040 in | 18 – 24 | 120 – 250 | 2,5 – 7,0 / 98 – 276 | 75Ar/25CO₂ |
| Carbon steel A36 | ER70S‑6 | 1,2 mm / 0.045 in | 20 – 28 | 180 – 320 | 3,0 – 8,5 / 118 – 335 | 75Ar/25CO₂ |
| Stainless steel 304 | ER308L | 1,0 mm / 0.040 in | 16 – 20 | 90 – 200 | 2,5 – 7,5 / 98 – 295 | 98Ar/2CO₂ |
| Stainless steel 304L | ER308L | 1,2 mm / 0.045 in | 18 – 24 | 130 – 280 | 3,0 – 9,0 / 118 – 354 | 98Ar/2CO₂ |
| Aluminum 6061‑T6 | ER4043 | 1,2 mm / 0.045 in | 20 – 26 | 130 – 260 | 4,5 – 11,0 / 177 – 433 | 100 % Ar |
| Aluminum 5052‑H32 | ER4043 (or ER5356) | 1,6 mm / 1/16 in | 22 – 28 | 180 – 320 | 4,0 – 9,0 / 157 – 354 | 100 % Ar |
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the main difference between ER70S-6 and ER70S-3?
Section titled “What is the main difference between ER70S-6 and ER70S-3?”ER70S‑6 contains higher manganese and silicon levels (Mn 1,40‑1,85%, Si 0,80‑1,15%) compared to ER70S‑3 (Mn 0,90‑1,40%, Si 0,45‑0,70%), which gives it better deoxidation and tolerance to surface oxides, but produces a slightly wider bead with greater presence of glassy silicates on the surface.
Can I weld stainless steel 316 with ER308L wire?
Section titled “Can I weld stainless steel 316 with ER308L wire?”It is not recommended as a general practice. Stainless steel 316 contains molybdenum (2‑3%) for pitting corrosion and chloride resistance, and ER308L lacks that element. To weld 316 or 316L, a ER316L wire that does add molybdenum must be used.
Why does aluminum wire tangle or bird-nest in the feeder?
Section titled “Why does aluminum wire tangle or bird-nest in the feeder?”Aluminum is a soft material and deforms easily. To avoid bird-nesting, use U-groove drive rolls, a spool gun or push-pull system, a Teflon liner, and adjust drive roll pressure to the minimum that ensures firm feed.
Which shielding gas is most suitable for ER308L?
Section titled “Which shielding gas is most suitable for ER308L?”The most common mixture is 98% argon + 2% CO₂ (or 98% Ar + 2% O₂). The small percentage of active gas stabilizes the arc and improves pool fluidity, maintaining low surface oxidation and good corrosion resistance.
Is ER4043 suitable for welding aluminum castings?
Section titled “Is ER4043 suitable for welding aluminum castings?”Yes, ER4043 is one of the preferred choices for repairing cast aluminum parts (die casting or sand casting) because its high silicon content lowers the melting temperature, improves fluidity, and minimizes hot cracking typical of castings.
What wire diameter should I choose for thin steel sheet?
Section titled “What wire diameter should I choose for thin steel sheet?”For thicknesses below 3 mm / 0.12 in, a diameter of 0,8 mm / 0.030 in is recommended. It provides a more stable arc at low amperage, lower penetration, and better pool control to avoid burn-through.
Sources Consulted
Section titled “Sources Consulted”- engineeringtoolbox.com: https://www.engineeringtoolbox.com/awg-wire-gauge-d_731.html
- efunda.com: https://www.efunda.com/
- manufacturingguide.com: https://www.manufacturingguide.com/en/svetsning?page=1