Effect of the additional water-cooling on the microstructure and mechanical properties of wire arc additive manufacturing of 4047 aluminum alloy

In order to solve the problem of deposited metal collapse caused by heat accumulation effect during the continuous process of wire arc additive manufacturing, a water-cooling aluminum plate was applied to the bottom of the substrate, and 4047 aluminum alloy straight wall components were prepared under two processes: intermittent forming with water-cooling, and continuous forming with water-cooling. A component was also additived without water-cooling for benchmark specimen. By comparing the thermal cycle curve, grain morphology, tensile strength, hardness and elongation, the effect of water-cooling conditions on the macroscopic morphology, microstructure and mechanical properties of the additive components were analyzed. The results showed that heat accumulation was effctively reduced by water-cooling, and flatter component side walls were obtained. The straight wall additive component exhibited the best performance under the continuous forming with water-cooling, showing no collapses at either end, and the forming efficiency was also high. The grains at the bottom of the components are mainly equiaxed crystals, and columnar and dendritic crystals at other sites. The grain size of the component is the largest under continuous forming with water-cooling and the smallest under intermittent forming with water-cooling. The mechanical properties of all components are similiar to that of ZL102 casting aluminium alloy. The component prepared by the intermittent forming with water-cooling exhibited the best mechanical properties.