ER309/309L  is very similar to type 309 except for the carbon content being lower than .03%.  The extra low carbon content provides good resistance to carbide precipitation and intergranular corrosion.

AWS Specification
AWS A5.9/A5.9M:2006

AWS Classification

ER309
309L

Welding Current

MIG-DCEP

TIG-DCEN

Typical Wire Chemistry
C 0.03
Cr 23.0-25.0
Ni 12.0-14.0
Mo 0.75
Mn 1.0-2.5
Si 0.30-0.65
P 0.03
S 0.03
Cu 0.75

Typical Mechanical Properties
(As Welded)
Yield Strength, kpsi 58*
Tensile Strength, kpsi 86*
Elongation%, min 40*

*AWS Requirement, Not Specified

Welding Positions

F,V,OH,H