OBRABOTKAMETALLOV technology Vol. 26 No. 2 2024 At the moment, there are a huge number of techniques for layer-by-layer building of products, but one of the main methods of additive manufacturing is laser surfacing. The reason for this is the versatility, simplicity, and widespread use of the technology [6]. This technique allows obtaining parts with low surface roughness due to smaller laser beam size, smaller layer thickness and short step compared to other additive technologies. Also, this preparation method allows applying additional material on the finished product for the purpose of repair and restoration of the part [5–8]. Laser technology ensures the production of dense parts without oxidizing the surface during the building process due to the use of a protective gas environment and allows the use of several materials in one assembly (Functionally Gradient Material or FGM specimens) [9–13]. Nowadays there is a huge amount of research on various aspects of laser additive technologies and one of the most common topics is optimization of processing parameters. Precisely because of the correctly selected modes of layer-by-layer build-up it is possible to assess the presence of physical defects, which indicates the quality of the obtained products [5, 8], and allows to increase the efficiency of production [7]. The topic of parameter optimization has been dealt with by scientists using various research techniques. In [5], the authors selected modes of single-track formation for a fiber laser by enumerating the most used modes in the planning matrix. In study [14], the authors used regression analysis technique to determine the effect of coaxial nozzle fiber laser power, surfacing speed, and powder distribution in the feed jet on the generated tracks. They found that at constant laser power, the height and cross-sectional area decreased with increasing surfacing speed, while the height and cross-sectional area increased with increasing powder feed rate. At constant speeds and varying power, the cross-sectional area increases, and the powder distribution has no effect on the track geometry. Similar results were obtained by the authors of the paper [7] using the ANOVA (analysis of variance) technique. They concluded that different parameters affect the geometric dimensions of the track in different ways. The track height is mainly influenced by the surfacing speed and powder feed rate. The influence of power is about 1 %. However, in the track width study, power and scanning speed were the main influencing factors. In [15], the effect of different fiber laser modes on single track formation was also studied. The authors confirmed that increasing the powder feed rate negatively affects the bond quality between the surfaced track and the substrate, the laser travel speed negatively affects the cross-sectional area and positively affects the surfaced track width. The laser power has a significant effect on the height and width of the formed track, compared to the scanning speed and powder feed rate. Since different studies use different equipment and different materials, despite the identical technology of layer-by-layer surfacing, the results obtained may differ significantly. Thus, this topic is still relevant. Therefore, the purpose of this work is to determine the most important laser radiation parameters affecting the surfacing process and the optimal mode for obtaining high-quality single tracks from AISI 316L steel with the use of a fiber laser. Methods and materials Investigated material AISI 316L steel powder was used to investigate the influence of build-up modes on obtaining highquality single tracks. The average particle size was 15–45 μm. Surfacing of steel powder was carried out on a plate made of 0.12 C-18 Cr-10 Ni-Ti steel with dimensions of 50×50×5 mm. The chemical composition of the alloys used is presented in Table 1. Ta b l e 1 Chemical composition of the materials under study Material Chemical element, wt. % C Mn Si S P Ti Cr Ni Fe AISI 316L 0.025 0.84 0.68 0.015 0.01 0.71 18.69 8.84 Bal. 0.12 C-18 Cr-10 Ni-Ti 0.11 1.082 0.447 0.002 0.027 0.002 17.15 7.85 Bal.
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