AlSi7Mg (4043) alloy is a special aluminum-silicon alloy for MIG and TIG welding. The presence of Mg allows it to respond effectively to heat treatment. It is used for welding and repairing heat-treatable foundry alloys such as AlSi7Mg and 357.0. After heat treatment, the weld bead acquires the same mechanical properties as the base metal. The alloy, like all 4xxx alloys, has excellent flow characteristics and low sensitivity to hot cracks.