Silicon bronze welding wire Size: S 201 composition: Sn1 Si0.3Mn0.3Cu Rem. Description: Good mechanical properties and crack resistance. Gas welding and argon arc welding of red copper. Equivalent to AWS : ERCu Size: S 211 Composition £º Si3 Mn1 Cu Rem. Description: Good mechanical properties. Argon arc welding of copper alloys and MIG brazing of steel. Equivalent to AWS: ERCuSi-A