Welding wire for ASTM A 621 Welding wire for ASTM A 621 Ratheesh_n (Mechanical) (OP) 24 Jan 17 11:11 Dear All, What is the filler wire to be used for MIG welding for welding of sheet metal ASTM A 621 ? RE: Welding wire for ASTM A 621 Ron (Structural) 24 Jan 17 12:55 A general purpose, mild steel wire should be sufficient. One example is Lincoln ER70S-6. I don't practice much in this area anymore, so there might be something better out there. A bit more information on your application would be helpful. RE: Welding wire for ASTM A 621 metengr (Materials) 24 Jan 17 13:12 Agreed, SFA 5.18 ER70S-6. See excerpt below from the referenced SFA specification; A7.4 ER70S-6 [ER48S-6]. Electrodes and rods of the ER70S-6 [ER48S-6] classification are intended for both single- and multiple-pass welding. They are especially suited for sheet metal applications, where smooth weld beads are desired, and structural and plate steels that have moderate amounts of rust or mill scale. These electrodes permit the use of higher current ranges with either CO2 (AWS A5.32 Class SG-C) shielding gas or with mixtures of argon and oxygen (AWS A5.32 Class SG-AO-X) or argon and carbon dioxide (AWS A5.32 Class SG-AC-Y). However, these electrodes do require a higher level of oxidation than the previously described electrodes when using either binary or ternary argon shielding gas mixtures per the AWS A5.32 specification. Typical base metal specifications are often the same as those for the ER70S-2 [ER48S-2] classification.