Evolution of the Phase Composition of High-Strength Laser Welded Joints of Aluminum-Lithium Alloys. 1. Features of the Structural and Phase Composition

The phase composition of laser welded joints of heat-hardenable aluminum–lithium alloys of the 3rd generation of grades V-1461 and V-1469 is studied. The phase composition of the alloys in the initial state and in laser welded condition is determined using synchrotron radiation and high-resolution transmission electron microscopy. It is shown that the weld structure is significantly affected by the thermal mode of the laser welding and by the variation of the temperature of the metal during the welding. The formation of the dendritic structure is shown to depend on the relation between the crystallization parameter G/R and the cooling rate dT/dt = GR. The energy parameters of the fiber laser welding are optimized, i.e., the welding speed, the radiation power, the location of the focal spot.