Study on Porosity Formation Mechanism in Laser Welding 1420 Al-Li Alloy

摘要

Comparing with the traditional 2000, 7000 series aluminum alloys, the addition of Lithium in 1420 Al-Li alloyrndecreases density by 12% and increases Young's modulus(E) by 8%, furthermore, it has excellent corrosionrnresistance and elevated temperature properties. Laser welding， as a fast and efficient welding method, however,rnhas a serious porosity formation tendency in laser welding 1420 Al-Li alloy. In this paper, we have systematicrnanalysis of possible porosity formation mechanism in laser welding 1420 Al–Li alloy. It was indicated that thernsurface substances is main Hydrogen source, and must be cleaned up thoroughly. Moreover, alloy elements, suchrnas Mg and Li, not only increase the hydrogen solution capacity of weld pool, but also increase the instability ofrnkeyhole tip. Thus, in order to minimize this instability and improve weld pool's motion, appropriate penetrationrnmode should be employed.