When should I use ER308L, ER309L, ER316L or ER347 filler metal?
ER308L (including ER308LSi) is predominately used on austenitic stainless steels, such as types 301, 302, 304, 305 and cast alloys CF-8 and CF-3. For high temperature applications such as in the electrical power industry, the high carbon 308H electrode provides better creep resistance than does 308L.
ER316L (including ER316LSi) filler metal should be used with ER316L and ER316 base metals. CF-8M and CF-3M are the cast equivalents of 316 and 316L, respectively.
Use ER309L (including ER309LSi) when joining mild steel or low alloy steel to stainless steels, for joining dissimilar stainless steels such as 409 to itself or to ER304L stainless, as well as for joining 309 base metal. CG-12 is the cast equivalent of 309. Some ER308L applications may be substituted with ER309L filler metal, but ER316L or ER316 applications generally require molybdenum and 309L contains no molybdenum.
Type ER347 stainless steel filler metal is ideal for ER347 and ER321 base materials because it matches these stabilized grades. CF-8C is the cast equivalent of ER347. Type ER347 filler metal is also suitable most ER308L filler metal applications.