OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 3 2024 Research methods The research was carried out on a 3D printer VARISKAF-100MVS manufactured in Yurga Institute of Technology of Tomsk Polytechnic University. The unit is equipped with a 100 W ytterbium fiber laser with a wavelength of 1,070 nm. The process of formation and study of the AlSiMg powder from single-component powders of aluminum, silicon and magnesium was described previously in [21]. To analyze the influence of the scanning strategy on the microstructure, elemental composition, porosity and density of the specimens the conditions were determined by search experiments and described in the paper [22]. Specimens with a size of 10×10×3 mm were produced under the following mode parameters: scanning speed V = 225 mm/s, scanning step S = 0.08 mm, laser power P = 90 W, powder layer thickness h = 0.025 mm. The temperature of the working table at the beginning of the SLM cycle was +25 °C; the powder was melted in the protective argon environment. An energy density of 200 J/mm3 provided sufficient heat to melt the powder and promoted the remelting of the part of the previous layer and melt path to smoothly connect the adjacent layers [22]. After formation the specimens were ground and polished using diamond pastes, removing 400 µm of the top layer. Porosity was determined as the average value from nine optical images of the polished section surface. The shooting pattern is shown in Figure 1. Fig. 1. Shooting pattern Studies of the structural-phase state of the specimen were completed using a transmission electron microscope JEOL JEM-2100. Shooting conditions were as follows: accelerating voltage of 200 kV, magnification of 6,000– 1,500,000 times, “column length” under the microdiffraction mode of 100 cm. The phase identification was carried out using the international card database ICDDPDF4+ (International Center for Diffraction Data). To study the effect of scanning strategy on the microstructure and porosity of the specimens, four strategies were implemented. Scanning strategy I (∠ 90), in which the direction of laser movement changes by an angle of 90° from layer to layer, is shown in Figure 2. (See the marks below) Fig. 2. Scanning strategy I (∠ 90) With scanning strategy II (∠ 45) the direction of laser movement changes by an angle of 45° from layer to layer, see Figure 3.
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