Aluminum is widely used, divided into cold hardening and heat treatment to strengthen two broad categories. Spot welding of aluminum is poor, especially the heat treatment to strengthen aluminum alloys. Its causes and the process should take the following measures:

(1) high electrical conductivity and thermal conductivity must be higher current and shorter time to achieve sufficient heat to form both the nugget; can reduce the surface overheating, to avoid

copper electrode and welding electrode adhesion to the aluminum package stratified diffusion, reducing the corrosion resistance of joints.

(2) Plastic narrow temperature range, linear expansion coefficient must be greater pressure on the electrode, the electrode is good with the move to avoid nugget solidification, because the content is too large cracks caused by tensile stress. Tendency of large aluminum alloy on the crack, such as LF6, LY12, LC4, but also in forging force must be used to increase the ways in which a sufficient nugget solidification of the plastic deformation and reduce the tensile stress in order to avoid cracks. Bending the electrode in the set bear a large forging force, they can add in the slow cooling after welding pulse pulse method avoids cracks. For large thickness of the aluminum electrode and can be used two ways.

(3) surface oxide film is easily produced to strict clean-up before welding, otherwise easily lead to undesirable splash and nugget shaped (tear checks, irregular nugget shape, convex sets and the hole is not rounded), so that joint strength reduced. Clean-up will lead to uneven solder joint strength stable.