Due to the difference in physical and chemical properties between the oxide layer and the aluminum base metal (usually the melting point and resistivity of the oxide layer are higher than that of the aluminum base metal), it is necessary to adopt the technological means of "first electrify to destroy the oxide layer and then weld the base metal", that is, first break through the oxide layer with high peak current (I1, T1) in a short time, and then connect with the normal base metal Current required for welding (I2, T2).