Abstract
The resulting properties of parts fabricated by wire and arc additive manufacturing (WAAW) processes are determined by their microstructure, local composition, and porosity. The objective of this work is to compare the difference of the solidification behaviors by means of numerical simulation when it precisely deposits material upon the single- and multiple-layer. Here, a three-dimensional (3D) heat transfer and fluid flow model of arc-based additive manufacturing to calculate thermal-flow fields, deposit shape and size, cooling rates and solidification parameters was developed. The calculated fusion zone geometries for the single- and multiple-layer deposition processes considering convective flow of melts agreed well with the corresponding experimental data for AA2319 deposits. It was found that under the same process parameters, the cooling rate and the solidification rate of the molten pool for the single-layer deposition process are always greater than that for the multiplelayer deposition process. Specifically, the refined equiaxed grains are more easily obtained at a cooling rate greater than 50 K ps−1 when the polarity is designated as direct current electrode positive
(DCEP). Width of the deposited bead of multi-layer structures is significantly greater than that of single-layer structures due to the lack of material at the lateral sides and the ambient conditions for the heat loss.
