Weld Mold 4325 description: Weld Mold 4325 is a silicon bronze alloy recommended for fabrication and repair of silicon bronzes and iron-based materials. Used for welding galvanized, cast and malleable iron, copper based alloys, steel and silicon bronze. Excellent for welding cast iron to steel and when welding dirty, oily or burned cast or malleable iron, also for galvanized iron and for joining cast iron to steel.