# ER70S-2 filler metal

Triple-deoxidized carbon-steel solid filler: classification, TIG/MIG applicability, product test conditions and handling.

Reviewed: 2026-11-01

Tags: consumables, welding, carbon-steel

Lincoln's **SuperArc L-52 ER70S-2** typical as-welded GMAW results are **520 MPa tensile and 30% elongation with 100% CO₂**, and **586 MPa and 28% with 90% argon/10% CO₂**. The CO₂ requirement row lists **480 MPa minimum**. Compare gas, procedure and all-weld-metal test basis before using the figures. [Lincoln Electric, *SuperArc L-52*, issue July 2019](https://ch-delivery.lincolnelectric.com/api/public/content/cdb3c4e7267a4441823fbc3dc06c9569?v=4d9cbb60)

## Identity and scope

AWS A5.18 and ASME SFA-5.18 cover ER70S-2 bare carbon-steel filler. Midalloy supplies it for GMAW or GTAW. Specify the product and form for the chosen shielding and feed. [Midalloy, *Mild and Low-Alloy Products*](https://www.midalloy.com/products/mild-low-alloy/)

Specify the manufacturer/product, process, diameter, package and required standard edition. A TIG cut length and a continuously fed spool have different handling and feeding requirements even when both carry ER70S-2. CIGWELD's **WeldSkill 70S** sheet, for example, identifies its copper-coated rods for TIG and gas-fusion welding, while Lincoln's **SuperArc L-52** is explicitly a GMAW wire. A process recommendation must follow the particular product, not just the alloy label. [CIGWELD, *WeldSkill 70S Series*, V1-2025](https://www.cigweld.com.au/wp-content/uploads/elementor/forms/CIG-7071-WS-70S-TIG-Rods-data-sheet-V2_WEB-1.pdf), [Lincoln Electric, *SuperArc L-52*, C4.10.24, July 2019](https://ch-delivery.lincolnelectric.com/api/public/content/cdb3c4e7267a4441823fbc3dc06c9569?v=4d9cbb60).

## What triple deoxidation means

The name refers to additions of **aluminum, titanium and zirconium**, alongside the wire's manganese and silicon. Midalloy identifies Ti, Zr and Al as the deoxidizers that support use on mild steels with rust or dirt. This is a consumable capability claim, not permission to leave oil, coatings, heavy scale or unknown contamination in a joint. Its typical chemistry lists titanium 0.10%, zirconium 0.07% and aluminum 0.10%; these are product values rather than universal delivered analyses. [Midalloy, *ER70S-2 Technical Bulletin*](https://www.midalloy.com/wp-content/uploads/2016/08/Midalloy-ER70S-2.pdf).

CIGWELD likewise describes tolerance to surface rust and mill scale but still instructs users to thoroughly clean areas before TIG welding. Preserve both parts of that guidance. Deoxidizers can help manage oxygen-related weld behavior; they do not establish the identity, weldability or safety of an unknown surface coating. [CIGWELD, *WeldSkill 70S Series*, V1-2025](https://www.cigweld.com.au/wp-content/uploads/elementor/forms/CIG-7071-WS-70S-TIG-Rods-data-sheet-V2_WEB-1.pdf).

## Classification versus measured properties

The “70” class should not be read as a guaranteed finished-joint strength. Lincoln's L-52 sheet cites **AWS A5.18/A5.18M:2017 ER70S-2** and separates requirements from typical all-weld-metal results. Its as-welded data illustrate shielding-gas dependence:

| L-52 test condition | Typical tensile strength | Typical elongation |
|---|---:|---:|
| 100% CO₂ shielding | 520 MPa [76 ksi] | 30% |
| 90% argon / 10% CO₂ shielding | 586 MPa [85 ksi] | 28% |

The sheet's requirement row for the CO₂ condition lists 480 MPa [70 ksi] minimum tensile strength. Its disclaimer warns that actual weldments vary with procedure, plate chemistry, temperature and design. These test results are not a strength prediction for a different wire, gas or diluted joint. [Lincoln Electric, *SuperArc L-52*, issue July 2019](https://ch-delivery.lincolnelectric.com/api/public/content/cdb3c4e7267a4441823fbc3dc06c9569?v=4d9cbb60).

For material selection, establish the actual base steel, thickness, joint design and required service properties. Midalloy lists carbon-steel plate, pipe, fittings, castings and forgings among applications, but that list does not qualify every grade or repair. Its published sheet is dated 13 November 2013; do not treat a later website upload date as a new technical revision. [Midalloy, *ER70S-2 Technical Bulletin*](https://www.midalloy.com/wp-content/uploads/2016/08/Midalloy-ER70S-2.pdf).

## Difference from ER70S-6

The suffix is meaningful. Midalloy's separate ER70S-6 sheet lists a typical manganese content of 1.45% and silicon of 0.98%, compared with its ER70S-2 values of 1.15% Mn and 0.55% Si. ER70S-6 is also available for GMAW and GTAW, so the distinction is not simply “MIG wire versus TIG rod.” These are manufacturer examples of different chemistries; retain the specified classification when comparing puddle behavior, procedure qualification and required properties. [Midalloy, *ER70S-6 Technical Bulletin*](https://www.midalloy.com/wp-content/uploads/2016/08/TB-Midalloy-ER70S-6-Bare-Wire.pdf), [Midalloy, *ER70S-2 Technical Bulletin*](https://www.midalloy.com/wp-content/uploads/2016/08/Midalloy-ER70S-2.pdf).

Miller's filler-selection guidance recommends matching filler to the base material and explains that diameter has an operating window. It discusses ER70S-6 for mild-steel MIG and ER70S-2 among steel TIG options; those examples do not establish that either can replace every carbon-steel or low-alloy filler. No single filler serves aluminum, stainless steel, cast iron and mild steel alike. [Miller, *Choosing What Filler Metal to Use for DIY Welding Projects*](https://www.millerwelds.com/en-US/resources/knowledge-hub/welding-basics/choosing-what-filler-metal-to-use-for-diy-welding-projects).

## Process controls

In GTAW the tungsten maintains the arc while a separate rod supplies filler. CIGWELD's rod sheet specifies DC electrode-negative operation and welding-grade argon shielding for its TIG procedure. Those instructions do not determine the polarity or gas for a GMAW spool. Use the machine, torch and filler instructions together and set rod size, current, joint preparation and shielding through the applicable welding procedure. [CIGWELD, *WeldSkill 70S Series*, V1-2025](https://www.cigweld.com.au/wp-content/uploads/elementor/forms/CIG-7071-WS-70S-TIG-Rods-data-sheet-V2_WEB-1.pdf).

For thin steel, Miller identifies heat control, fit-up and material preparation as central to avoiding distortion and burn-through. It discusses ER70S-2 as a common steel TIG filler while distinguishing silicon-bronze joining as a brazing process. A lower-heat alternative is therefore not automatically an equivalent weld-metal substitution. [Miller, *Successfully Welding Sheet Metal with MIG and TIG*](https://www.millerwelds.com/en-us/resources/knowledge-hub/automotive-welding/successfully-welding-sheet-metal-with-mig-and-tig).

Record gas composition, polarity, filler diameter, current/voltage or waveform, feed arrangement, material and thickness when evaluating a setup. This is a practical selection checklist synthesized from the cited guidance, not an amperage, flow or preheat recipe. “Triple deoxidized” does not eliminate the need to control shielding or maintain clean filler and joint surfaces.

## Storage and handling

Protect bare wire and rods from humidity, oil, dirt and condensation. Lincoln's storage instructions for MIG wire and TIG rods call for protective packaging and say oxidized or seriously moisture-contaminated material cannot be restored to original condition and should be discarded. Do not apply a covered-electrode rebaking schedule to bare filler. Retain product and lot identification with opened packages so the consumable remains traceable to its actual specification. [Lincoln Electric, *Storage and Handling Instructions for MIG Wires and TIG Rods*, consumables catalogue p. 37](https://ch-delivery.lincolnelectric.com/api/public/content/8f62b7daa7104f118facf6c320f497f0?v=2fd828e3).

Aufhauser's **Mild Steel Bare MIG/TIG Wire/Rods SDS**, document **MSBER 202304**, prepared **April 2023**, explicitly includes its ER70S-2 alongside other products. It calls for avoiding welding fumes and gases, adequate ventilation, eye/skin protection for arc radiation and appropriate electrical precautions. Its supplied-ingredient information does not define every welding fume: the process and base material also matter. Use the SDS for the delivered product and an exposure assessment appropriate to the actual operation; the classification supplies no universal ventilation rate or respirator choice. [Aufhauser, *Mild Steel Bare MIG/TIG Wire/Rods Safety Data Sheet*](https://www.brazing.com/Pdf/MSDS/New-SDS-MildSteelBareER.pdf).