MIG welding wire that is 1 mm in diameter is a thicker wire that is commonly used for welding thicker materials or for welding in high current applications. It is made of stainless steel, which makes it corrosion resistant and strong. It is commonly used in the food processing, chemical, and pharmaceutical industries due to its resistance to corrosion and ability to be easily sterilized. The specific type of stainless steel used in the MIG wire may vary depending on the specific application, with common types including 304L, 308L, 309L, and 316L.

It is important to use the correct wire diameter for your MIG welding application. Using a wire that is too thin can result in weak or porous welds, while using a wire that is too thick can make it difficult to control the weld pool and can result in excess spatter. It is generally recommended to use the thinnest wire possible that is still able to provide sufficient strength for the intended application.