ER70S-6 welding wire is one of the most popular and widely used solid wires in MIG and TIG welding, especially for carbon and mild steel.
Known for its reliability and high-quality welds, ER70S-6 offers excellent versatility on slightly rusty or dirty steel surfaces due to its increased deoxidizers, such as manganese and silicon.
Whether you’re a hobbyist or professional, understanding the ER70S-6 welding wire specification is key to getting optimal weld strength, smooth bead appearance, and trouble-free performance.
This guide breaks down the ER70S-6 wire's meaning, chemical and mechanical specs, applications, and welding parameters in an easy-to-understand way.
ER70S-6 Welding Wire Quick Facts:
- ER70S-6 stands for: Electric Rod (ER), minimum tensile strength 70 ksi, Solid wire (S), variant 6 indicating higher manganese and silicon deoxidizers.
- Complies with AWS A5.18 / ASME SFA A5.18 specifications.
- Typical chemical composition: C 0.06-0.15%, Mn 1.40-1.85%, Si 0.80-1.15%, plus trace Cu, Cr, Ni.
- Minimum tensile strength: about 70,000 psi (480 MPa).
- Known for excellent weld bead fluidity and suitability on slightly dirty/rusty steel.
- Used widely in general fabrication, automotive, construction, pressure vessels, and farm equipment.
- Compatible with CO₂ or Ar+CO₂ shielding gases.
- Sizes commonly range from .023" to 1/16" diameter wire.
You May Want to Shop 🛒
What Does ER70S-6 Mean?
Understanding the code helps you know exactly what type of wire you’re using:
- ER: "Electric Rod" - a solid wire filler metal used in welding.
- 70: Minimum tensile strength of 70 ksi (70,000 psi).
- S: Solid wire (not flux-cored).
- 6: The designation that indicates the wire composition has higher amounts of manganese and silicon deoxidizers compared to other variants.
This naming convention follows specifications by the American Welding Society (AWS), specifically for carbon and mild steel wires.
Chemical Composition of ER70S-6 Wire
|
Element |
Typical Range (%) |
|
Carbon (C) |
0.06 – 0.15 |
|
Manganese (Mn) |
1.40 – 1.85 |
|
Silicon (Si) |
0.80 – 1.15 |
|
Phosphorus (P) |
≤ 0.025 |
|
Sulfur (S) |
≤ 0.035 |
|
Copper (Cu) |
≤ 0.50 |
|
Trace elements (Ni, Cr) |
Minimal |
The higher manganese and silicon help clean the weld pool by deoxidizing impurities. This allows ER70S-6 to perform well on steel with slight rust or dirt, where other wires might struggle.
Mechanical Properties
|
Property |
Typical Value |
|
Tensile Strength |
70,000 psi (480 MPa) |
|
Yield Strength |
~58,000 psi (400 MPa) |
|
Elongation |
22% (measured over 2") |
These properties ensure welded joints have strength suitable for most engineering and structural applications, delivering durability and safety.
Common Applications of ER70S-6 Welding Wire
- Structural steel fabrication (beams, channels, frames)
- Automotive body and repair work
- Construction equipment and scaffolding
- Pressure vessels and pipe welding
- Farming and agricultural equipment
- General-purpose sheet metal welding
Thanks to its ease of use and tolerance for less-than-clean metal surfaces, ER70S-6 is a go-to wire for many professional environments.
Welding Parameters and Shielding Gases
|
Wire Diameter |
Amperage Range |
Wire Feed Speed (in/min) |
Typical Shielding Gas |
|
0.023" |
30-85 |
150-300 |
100% CO₂ or Argon/CO₂ mix |
|
0.030" |
40-130 |
200-450 |
80% Ar / 20% CO₂ |
|
0.035" |
60-235 |
300-600 |
95-98% Ar / 2-5% CO₂ |
|
0.045" |
90-290 |
600-850 |
80% Ar / 20% CO₂ |
|
1/16" |
150-400 |
800-1200 |
80% Ar / 20% CO₂ |
Shielding gas tips:
- Argon-CO₂ mixes provide a stable arc and cleaner welds.
- 100% CO₂ increases penetration but can cause more spatter.
- Selecting the proper gas type depends on your welding requirements and surface cleanliness.
Selecting Wire Size and Welding Settings
- For thinner materials (<1/8"), use smaller wires like 0.023" or 0.030" to control heat input and prevent burn-through.
- Thicker metals (>1/4") allow larger diameter wires (0.045" to 1/16") for higher deposition rates.
- Consider your welding position; smaller wires are easier for out-of-position work.
- Adjust the amperage and voltage according to the wire size and material thickness for optimal arc stability.
Differences Between ER70S-6 and Other ER70S Wires
|
Wire Type |
Deoxidizer Content |
Best For |
|
ER70S-2 |
Low |
Clean, prepared steel surface |
|
ER70S-3 |
Moderate |
Slightly rusted or dirty metals |
|
ER70S-6 |
High |
Rusty, oxidized steel; more forgiving |
ER70S-6 is the most forgiving in terms of surface cleanliness, making it versatile on construction sites or repairs.
👉 Read Related Article: MIG Welding Wire Speed & Voltage Chart: Settings & Guidelines
Final Thoughts
Understanding the ER70S-6 welding wire specification empowers welders to choose the right wire and settings for their projects, resulting in strong, clean, and reliable welds.
With its higher manganese and silicon content, ER70S-6 adapts well to less-than-perfect steel surfaces and offers excellent bead formation.
If you want consistent performance, whether welding thin sheet metal or heavy structural steel, ER70S-6 remains an excellent choice.
For high-quality ER70S-6 welding wire and other welding supplies, explore the trusted collections at Arccaptain:
FAQs about ER70S-6 Welding Wire Specification
What does ER70S-6 mean in AWS A5.18?
ER means the wire can be used as an electrode or rod, 70 is the 70,000 psi minimum tensile strength of the deposited weld metal, S is solid wire, and 6 identifies the chemistry group with higher silicon and manganese. This chemistry helps clean the puddle during welding.
What is ER70S welding wire used for?
ER70S wires, such as ER70S-6, are used to weld mild and low-alloy carbon steel. You will see them in general fabrication, automotive repair, frames, pipes, and sheet to medium-thickness plate. They are chosen for clean appearance and strong, ductile welds. The added deoxidizers help when the steel is not perfectly clean.
What positions can ER70S-6 weld in?
ER70S-6 can weld in all positions when the settings and technique are correct. Flat and horizontal are easiest for new welders, while vertical and overhead need tighter control of heat and travel speed. Use shorter stick-out and proper gun angle to keep a stable arc. Follow the WPS or maker’s data for volts, wire feed, and gas flow.
Does the ER70S-6 wire need gas?
Yes. ER70S-6 is a solid MIG wire for GMAW, and it needs shielding gas. Common mixes are 100% CO₂ or 75/25 Ar/CO₂ for a cleaner bead and less spatter. It is not a flux-cored, self-shielded wire.
What happens if I use MIG wire without gas?
If you run ER70S-6 without shielding gas, the arc pulls in air and the weld becomes porous and weak. You will see pinholes, soot, and brittle beads. Lack of gas also hurts fusion and can cause cracking. If you need “gasless” welding, switch to a self-shielded flux-cored wire designed for that.