Laser Welding Of High Strength Aluminum With Powder

High strength aluminum alloys are used in a wide range of engineeringapplications, which include aerospace, automobile, light railway etc. Since thesealloys are not easy to weld, they must be joined by bolts and rivets when assembled asstructures. Such mechanical joints are disadvantageous for reduce weight andconstruction cost. Laser beam has very high power intensity, there is an increasinginterest in applying laser beam welding to aluminum alloys since it offers advantagessuch as high welding speeds and low distortion. However, porosity and hot crack areoften encountered in laser welding as well as in conventional processes. To minimizethis problem, filler wire are used in laser welding. Just like filler wire ,powder metalhave the same effect, otherwise, it is more flexible than wire in the weld. In this paper,we do some theoretical and experimental studying on aluminum powder welding. To meet the specialty of laser powder welding, we designed a three-plyself-bundling coaxial powder injecting head which can both feed the powder metaland provide shielding gas. Its function has been approved in experiments is good. High speed camera shoot show the moving of the welding pool is steady anduniform. By metallographic analyzing of the welded seam, the conclusion can bemade that it can well eliminate the hot crack and porosity when the weld adopt AlSi12powder alloy metal. Adopting optimized processing parameters we have welded 7075 aluminumsuccessfully by injecting powder filler metal to the welding pool with high powerYAG laser. Both sides of the welded seam is full filled and without defect such asundercut, excessive penetration, discontinuous etc on the surface of seam .the porosityis low and the hot crack is eliminated also. The tension experiment shows that thetensile strength of the 7075(T73)Al alloy can reach 370MPa.