4047 aluminum sheet belongs to one of the 4-series alloys. The 4-series aluminum alloy is an aluminum alloy with silicon as the main alloy element. Most of the alloys are heat-treated non-strengthened aluminum alloys, which refer to alloys containing some Mg and Ni, etc., and Strengthening by heat treatment is only possible when certain elements are absorbed after the alloy is strengthened by welding heat treatment.