ER309L Welding wire specification & properties

ER309L welding wire

ER309L welding wire is a versatile TIG and MIG welding wire rod available in straight wire and wire spools. This wire contains 24% Cr and 13% Ni as primary alloying elements. 

ER309L is used for welding similar alloys, welding of stainless steel to mild steel, carbon steel and low alloy steel. ER309L is also used to weld 304 stainless steels when corrosion resistance for weld is required.

ER309L is the low carbon variant of ER309 filler wire giving high intergranular corrosion resistance and sensitization without any addition of titanium or niobium.

ER309L Welding wire rod Specification

ER309L welding wire rod specification is AWS A5.9. ER309L is the classification number for this wire. AWS A5.9 specifies the chemical composition requirements and test required for this classification.

ER309L welding wire

ER309L TIG MIG Wire Chemical Composition

ER309L welding wire is primary composed of 23- 25% Cr, 12-14% Ni, 0.75% moly and 0.75% copper. The full chemical composition required as per AWS A5.9 for ER309L classification is given in the below table:

C%Cr%Ni%Mo%Mn%Si%P%S%N%Cu%
0.0323.0-25.012.0- 14.00.751.0- 2.50.0- 0.650.030.030.75
Single values are maximum permitted.

ER309L wire mechanical properties

ER309L Mechanical properties are not specified in AWS A5.9 specification. The typical as welded ER309L tensile strength is 590 MPa (85 Ksi) and ER309L yield strength is 440 MPa (63 Ksi). ER309L filler rod being an austenitic stainless-steel filler has around 35% elongation.

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A summary of typical ER309L mechanical properties are:

  • Tensile Strength: ≈ 590 MPa (85 Ksi).
  • Yield strength: ≈ 440 MPa (63 Ksi).
  • Elongation: ≈ 35%.

ER309L A Number and F Number

AWS A5.9: ER309L Welding wire A-Number is “8” (Same for TIG and MIG welding) and F Number is “9”.

ER309L vsER309LSi

Both ER309L and ER309Lsi are having similar metallurgy and applications. The main difference between ER309L and ER309LSi is the amount of silicon alloying. ER309L contains 0.30- 0.65% silicon while the ER309LSi contains 0.65- 1.00% silicon.

Read more: ER308LSi vs ER309LSi vs 316LSi

The higher silicon present in ER309LSi gives superior molten weld pool fluidity which is beneficial for MIG welding. In MIG welding, we have a higher molten weld pool compared to TIG. Adding higher silicon gives good usability characteristics to this wire for GMAW applications.

Although, being an austenitic stabilizer Silicon gives rise to high austenite in weld metal. This may be a concern for low ferrite weld deposit that are more prone to hot cracking. You can overcome this issue if you notice low ferrite by using higher welding heat input.

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ER309 vs ER309L

ER309L is the low carbon variant of ER309 welding wire. Both ER309 and ER309L has same chemical compositions except the carbon content. ER309L contain a maximum carbon of 0.03% while ER309 carbon content is up to 0.12%.

Due to high carbon, the tensile strength of ER309 is higher than ER309L. Although, on other side, the intergranular corrosion resistance of ER309L is higher than ER309.

ER309L Shielding Gas

ER309L shielding gas for TIG welding is pure argon. For MIG welding applications using ER309L, Argon98% + Oxygen 2% is commonly used. Oxygen is added to provide fluidity to the molten weld pool.

Read more: TIG & MIG Welding Gases for Stainless Steel Welding

ER309L TIG Rod

ER309L tig wire rod are manufactured as per AWS A5.9 specification. The wire is available in different diameters of 1/16” (1.6mm), 3/32” (2.4 mm), 1/8” (3.2 mm) and 5/32” (4.0 mm).

TIG welding using ER309L requires argon gas weld shielding and can be used to 304 or other stainless steel grades to carbon steel, low alloy steel, ferritic, martensitic, duplex stainless steel.

ER309L MIG Rod

ER309L Mig welding wire is manufacturered as per AWS A5.9 specification. MIG welding wires with ER308L classification are generally welded using argon + 2% oxygen welding shielding gas.

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ER309L mig wires are available in different diameters ranging from 0.25”, 0.035”, 0.45″ and 1/16”.

What is er309l used for?

ER309L is an austenitic stainless steel alloy that is widely used in the welding industry. It is a low-carbon version of ER309, which has a slightly higher carbon content. The “L” stands for low-carbon, and it allows welders to use this alloy without fear of cracking or embrittlement during welding processes.

ER309L is a versatile welding wire and mainly famous for dissimilar welding applications. It has excellent weldability characteristics and is often chosen for its good corrosion resistance properties, making it an ideal choice for many welding applications.

Er309L also provides good mechanical strength at high temperatures allowing for greater flexibility when welding different steels together. This makes it ideal for joining components made from different grades of stainless steel such as 304 to 309 or 316 to 317.


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