ER70S-6 welding wire MTC, specification, chemical-mechanical properties

What does ER70S-6 TIG/ MIG Welding wire mean?

ER70S-6 is a solid low carbon steel filler wire rod used for TIG Welding & MIG/MAG (GMAW) Welding applications.

ER70S-6 is used widely for welding of mild steel, plain carbon steel, and carbon steel. It is also used for dissimilar welding between carbon steel to Low alloy steel.

The wire can be used for thin sheet metal (Small diameters) and thick parts welding as well. The shielding gas when using the wire with Gas Tungsten Arc Welding (TIG) is pure argon.

Pure CO2 (C1 classification as per AWS A5.32) or a mixture of Argon+CO2 are used when using ER70S-6 (ER49S-6) with Gas Metal Arc Welding (MAG).

Each digit in the ER70S-6 classification has its own meaning. For example, ‘ER’ means electrode rod (filler wire) intended for TIG/MIG welding, ’70’ means the minimum tensile strength in KSi, ‘S’ refers to Solid wire and the last digit defines the chemical properties, gas shielding, and polarity of the wire as specified in ASME Section IIC, SFA 5.18.


ER70S-6 Filler wire AWS specification, F-Number, A Number

ER70S-6 specification is AWS A5.18. The CSA Specification for ER49S-6 is WB/CSA W48-06. The EN Equivalent of ER70S-6 is G 49A 3 C S6 as per EN ISO 14341-B.

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F-Number of ER70S-6 as per ASME Section IX is ‘6’. The A-Number of ER70S-6 as per ASME Section IX is ‘1’. Detailed chemical properties of ER70S-6 and other equivalent filler wires specified in AWS A5.18 are given below.

ER70S-6 Chemical composition & mechanical properties

ER70S-6 is mainly a carbon steel filler wire having Carbon, Manganese, and Silicon as the main alloying elements.

The main alloying element percentage in ER70S-6 is – Carbon is 0.06 to 0.15, manganese is from 0.40 to 1.85 and Silicon is 0.80 to 1.15.

What is the difference between ER70S-2 (ER49S-2) and ER70S-3 (ER49S-3)?

The minimum tensile strength of ER70S-6 (ER49S-6) is 70 KSi (480 MPa) and the Yield strength is 58 KSi (400 MPa) with a minimum percentage elongation of 22%.

Full chemical and mechanical properties as per AWS A5.18 (or CSA W48-06) of ER70S-6 or ER49S-6 are given in the table below for reference.

ER70S-6 welding wire parameters & MIG Setting

TIG welding & MIG welding parameters used for ER70S-6 depends on the wire diameters and welding position.

Below table gives recommended welding parameters for TIG/ MIG welding with 0.035”, 0.045′,’ 1/16”, 3/32”, 1/8”. The welding amperage (wire feed rate- WFS) increases with the increase in the wire diameters.

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High ampere will give higher weld deposition but it will be restricted to the flat welding position.

Performing the welding in overhead or vertical positions usually requires lower welding ampere and smaller wire diameters.

ER70S-6 Equivalent welding wire

The equivalent stick welding (SMAW) rod for ER70S-6 is the E7018 electrode. TIG/MIG equivalent wires of ER70S-6 is ER70S-2, ER70S-3, etc.

ER70S-2 is used widely due to good weld fluidity and higher deoxidizer elements present in the wire.

E7018-1 rod is also equivalent to ER70S-6 or ER70S-2. This rod gives higher weld toughness compared to the E7018 type rod.

What is the difference between ER70S-6 (ER49S-6) and ER70S-3 (ER49S-3)?

Does ER70S-6 Need gas?

Straight answer- Yes. ER70S-6 requires gas shielding as this filler wire is intended to be used with TIG welding or MIG/MAG welding.

Both TIG & MIG/MAG are gas-shielded arc welding processes that require external gas shielding to protect the weld pool oxidation from atmospheric gases.

Pure argon is used for TIG while pure CO2 or a mixture of argon+Co2 is used in MIG/MAG welding. Click here to learn about the shielding gases, their types, and their properties in welding.

ER70S-6 polarity

The welding polarity used for ER70S-6 is DCEP (Direct Current Electrode Positive). ER70S-6 is used mainly in TIG (GTAW) welding of carbon steel.

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So, DCEN polarity is used in TIG welding with ER70S-6 (ER49S-6). MIG/ MAG welding polarity for ER70S-6 is DCEP. Click here to learn about the types of polarity in welding.

ER70S-6 MTC & Datasheet

ER70S-6 MTC contains information about the chemical and mechanical properties of the filler wire. There are different types of welding electrode/ filler wire MTC. The main types are:

  1. CMTR- Certified material test certificate
  2. COC- Certificate of conformity
  3. TC- Test Certificate- Generally 3.1 for chemical and 2.2 for mechanical properties.

The choice of MTC is based on the purchaser’s requirements. Click here to download ER70S-6 MTC for reference.

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9 thoughts on “ER70S-6 welding wire MTC, specification, chemical-mechanical properties”

  1. Fantastic post however I was wondering if you could write a little more on this
    topic. I’d be very grateful if you could elaborate a little bit more on the weld deposit properties of ER70S-6 welding wire.

    • The minimum tensile strength of ER70S-6 (ER49S-6) is 70 KSi (480 MPa) and the Yield strength is 58 KSi (400 MPa) with a minimum percentage elongation of 22%.
      Refer above post for detailed weld deposit properties.

    • Hi, the AWS Specification for ER70S-6 welding wire is AWS A5.18. The A-Number as per ASME Section IX for ER70S-6 is 1.

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