Effect of Interlayer Delay on the Microstructure and Mechanical Properties of Wire Arc Additive Manufactured Wall Structures

Abstract

Wire arc additive manufacturing is a metal additive manufacturing technique that allows the fabrication of large size components at a high deposition rate. During wire arc additive manufacturing, multi-layer deposition results in heat accumulation, which raises the preheat temperature of the previously built layer. This causes process instabilities, resulting in deviations from the desired dimensions and variations in material properties. In the present study, a systematic investigation is carried out by varying the interlayer delay from 20 to 80 s during wire arc additive manufacturing deposition of the wall structure. The effect of the interlayer delay on the density, geometry, microstructure and mechanical properties is investigated. An improvement in density, reduction in wall width and wall height and grain refinement are observed with an increase in the interlayer delay. The grain refinement results in an improvement in the micro-hardness and compression strength of the wall structure. In order to understand the effect of interlayer delay on the temperature distribution, numerical simulation is carried out and it is observed that the preheat temperature reduced with an increase in interlayer delay resulting in variation in geometry, microstructure and mechanical properties. The study paves the direction for tailoring the properties of wire arc additive manufacturing-built wall structures by controlling the interlayer delay period.

Metallic Coatings through Additive Manufacturing: A Review

“…Thus, the over-aging in precipitate-hardened materials can be avoided [ 181 ]. However, inert shielding is required in the case of WAAM to avoid contamination, whereas electron beam direct energy deposition does not require this [ 182 , 183 , 184 ]. The laser beam methods induce a high-power electrical arc as a source of fusion which is beneficial for reflective metal alloys (Mg, Cu, Al, etc.)…”

Differences between Tensile Properties of WAAM SS304 Components in Different Directions

“…The microstructure of the sample presents a typical layer-by-layer microstructure. [31,32] The microstructures within and between layers are periodically distributed, and the fusion line distinguishes them clearly. This is due to the layer-by-layer AM process parameter inherent in WAAM.…”

Forming accuracy improvement in wire arc additive manufacturing (WAAM): a review

“…For example, changing the surface energy of the molten pool makes it difficult for droplets to spread. The droplet has a large wetting angle owing to the laser effect (Singh et al , 2022; Näsström et al , 2019; Singh et al , 2021; Chi et al , 2020), as shown in Figure 7. The outcome of using oscillating laser-assisted WAAM is the opposite; herein, the temperature distribution inside the molten pool is altered, which triggers an increase in the width of the deposited layer owing to the impact of the liquid metal from the bottom to the walls of the molten pool (Gong et al , 2020).…”

“…This is due to the small wetting angle at the interface between the deposited layer and droplets caused by the high-level interlayer heat accumulation, which causes the droplets to spread easily (Wang et al , 2021; Dong et al , 2021; Knezović et al , 2020). According to Singh et al (Singh et al , 2021), surface tension can suppress the spreading of droplets owing to the Marangoni or thermal capillary effect. In addition to unsatisfactory forming, interlayer heat accumulation causes thermal stresses and ultimately results in macrocracks or distortion (Li and Xiong, 2019; Wächter et al , 2020).…”