Laser Welding Characteristics Of Aluminum And Nickel-base Alloys Under Vacuum Environment

Under the atmospheric environment, Aluminum alloy will produces larger plasma during the laser welding process and is prone to cause the instable of the keyhole and fading of the laser power, which makes further effects on reducing penetration and produces porosity. As for the nickel base super alloy, it is difficult to form well during the laser welding process because of its poor liquidly and the instable plasmas. While the vacuum environment can effectively inhibit the generation of plasma and gains greater penetration, and then improve the welding quality. The paper mainly studies on vacuum laser welding characteristics of metal materials based on Aluminum alloy and Nickel base super alloy.Make A5083 being 6mm and 10 mm thick and 10 mm thick Nickel base super alloy as research objects. This paper compares laser welding characters under high vacuum and atmospheric environment. This study includes weld formation and physical properties, and discussing how 10 mm thick high-temperature Nickel-based alloy performance under the atmosphere at the same time. The results show that weld formation in a vacuum environment improved significantly, and at the same time, laser welding under the vacuum environment can get light welds without oxidation and plasmas, concomitant with low gas hole ratio and high stability.Subsequently, based on Aluminum alloy, the paper studies the effects of vacuum degree on welding properties, researches weld penetration and the shapes of plasma and discusses the porosity. The results show that with the improvement of vacuum degree, the weld penetration becomes bigger, the size of the plasma becomes smaller, the porosity is less and so on. For different metiaral, there always exists a threshold of vacuum degree on 101 Pa which is independent of the types of materials and the power of laser. This was taken as proof thatlaser welding in low vacuum environment can significantly improve the welding quality.At last, the paper set forth the reasons why vacuum environment changes the welding quality. Distinguish describe how vacuum degree affect laser welding from the collisions of particle under vacuum, and the relationship between the heat dissipation with vacuum, and how the boiling point of metal change with the vacuum improvement. Finally, analysis the threshold of vacuum degree from the volatilization rate of metal material and the changes of electron density in plasma.