Aluminum welding current several major difficulties:
① alloy welded joints soften serious, strength, low coefficient, which is the biggest obstacle to hinder the application of aluminum;
② aluminum oxide film on the surface is easy to produce relatively refractory (Al2O3 melting point of 2060 ℃), which requires the use of high-power welding process;
③ prone to porosity aluminum welding;
④ easy to produce aluminum hot cracking during welding;
⑤ linear expansion coefficient, easy to produce welding deformation;
⑥ large thermal conductivity of aluminum (about 4 times stronger than steel), at the same welding speed, heat input welding steel than 2 ~ 4 times.
Thus, aluminum welding requires a high energy density, small heat input welding, high welding speed and efficient welding methods.