Precipitation behaviors and the related strengthening mechanism in 2219 Al alloy fabricated by wire arc additive manufacturing

Normally, a large number of dislocations could be introduced into the metallic component in the additive manufacturing process. The effects of these thermal stress-induced dislocations on the precipitation of 2219 Al alloy have thus far not been comprehensively studied. In the present study, the precipitation behaviors of 2219 Al alloys fabricated by wire arc additive manufacturing are investigated in detail by multi-scale experimental methods, including transmission electron microscopy, scanning electron microscopy, and X-ray diffraction analyses. Our study suggests that the stress-induced dislocations could act as the heterogenous nucleation sites, facilitating the precipitation of 0 ' and 0 '' phases in the deposition process. During the subsequent artificial aging, 0 ' and 0 '' phases are present in the 160 degrees C peak-aged sample. Raising the aging temperature from 160 degrees C to 180 degrees C could facilitate the transformation of 0 '' to 0 ' phases. Moreover, for the 200 degrees C peak-aged sample, the number density of 0 ' phases appears to decrease with accompanied coarsening. An evident improvement occurs in the comprehensive mechanical properties of the as-deposited sample by appropriate heat treatment (540 degrees C/3 h180 degrees C/14 h). The ultimate tensile strength significantly increases from 238 MPa to 408 MPa, exhibiting an enhancement of approximately 70 %, while the elongation increases from 14 % to 15 %. Additionally, a quantitative correlation is established between the precipitate characteristics and mechanical properties.