I. Introduction
The LB-PBF process is a powder bed-based metal 3D printing technology. During the printing process, a laser beam is irradiated onto a bed of metal powder, causing the powder to melt and fuse into a pre-designed part shape. Compared with other 3D printing technologies, the LB-PBF process has the advantages of high material utilization and high printing speed, but it also faces challenges such as melt pool behavior control, thermal stress distribution and microstructure evolution. As a commonly used cast aluminum alloy, AlSi10Mg has excellent physical and mechanical properties, which is suitable for manufacturing parts with thin walls and complex geometric designs. The LB-PBF process is used to 3D print the AlSi10Mg thin-walled structure, which can give full play to the advantages of this material and improve the performance and manufacturing efficiency of the part.
2. Numerical simulation methods
In this paper, numerical simulation method is used to study the performance of 3D printing of AlSi10Mg thin-walled structures by LB-PBF process. A mathematical model was established to numerically simulate the process of molten pool formation, molten metal flow, and heat conduction involved in the printing process. The finite element method was used to solve the model, and the physical parameters, thermophysical parameters and laser irradiation parameters of the materials were considered. Through numerical simulation, the shape of the melt pool, the temperature field distribution, and the geometry and dimensional accuracy of the thin-walled structure at each moment in the printing process can be obtained.
3. Numerical simulation results and analysis
Through numerical simulation, the following results are obtained:
(1)Melt pool formation: Under laser irradiation, the metal powder melts rapidly, forming a molten pool. As the laser scanning speed increases, the size and temperature of the melt pool decrease. This is mainly due to the decrease in the amount of laser energy irradiated to the powder per unit time as the scanning speed increases, resulting in a decrease in the melt pool temperature.
(2)Molten metal flow: Under the action of a laser, the molten metal creates a flow that causes the liquid metal in the molten pool to move in the direction of the laser scan. The faster the scan, the more intense the metal flows. This is mainly due to the increased inertial force on the liquid metal in the molten pool as the scanning speed increases, resulting in increased metal flow.
(3)Heat conduction: Heat conduction is an important physical process during the printing process. Through heat conduction, heat spreads from the molten pool to the surroundings, resulting in an increase in the temperature of the surrounding area. The numerical simulation results show that the effect of heat conduction weakens with the increase of scanning speed. This is mainly due to the fact that as the scanning speed increases, the heat loss in the melt pool accelerates, resulting in a weakened heat conduction.
(4)Thin-walled structure performance: The geometry and dimensional accuracy of thin-walled structures at different scanning speeds are obtained through numerical simulation. The results show that with the increase of scanning speed, the dimensional error of the thin-walled structure increases, while the shape error decreases. This is mainly due to the increased flow of liquid metal in the molten pool as the scanning speed increases, resulting in the shape of the thin-walled structure being closer to the preset shape.
4. Conclusions
In this paper, the numerical simulation of 3D printing of AlSi10Mg thin-walled structures by LB-PBF process was studied. By establishing a mathematical model, numerically simulating the molten pool formation, molten metal flow, heat conduction and other processes involved in the printing process, and analyzing the influence of printing parameters on the performance of thin-walled structures, the results show that the scanning speed has an impact on the formation of molten pools, molten metal flow, molten metal flow, Thermal conduction and thin-walled structure performance have an important impact, in practical applications, the printing process can be optimized and the performance of thin-walled structures can be improved by adjusting the scanning speed and other parameters, and this research provides a theoretical basis and technical guidance for further optimizing the 3D printing of AlSi10Mg thin-walled structures by LB-PBF process
