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Original Title: Types, Causes and Adverse Effects of Defects in SLM Process Defects in SLM process can be divided into defects in powder spreading process and defects in printing process. Defects in powder spreading process include irregular powder layer, and defects in printing process include splash, spheroidization, pores, poor surface quality, cracks, geometric deformation, etc. Dr. Cao Longchao from Huazhong University of Science and Technology summarized the common defects and their formation mechanism in SLM manufacturing reported in the literature. The different defects and their formation process are introduced below, and the impact of different defects on the application of printing components is summarized. Defect is one of the biggest bottlenecks for the wide application of SLM technology in industry. 1. Splash Splash is one of the most common defects in SLM process, which can directly affect the interaction between laser and material and lead to other defects. The study shows that the spatter is mainly caused by the lateral shielding gas flow, the fluctuation of the molten pool and the recoil pressure. The splashing on the powder will form large metal particles, and then produce underfusion and porosity defects, which are harmful to the tensile strength and fatigue performance of the component. In addition, the splashing on the surface of the solidified layer will affect the next layer of powder, resulting in the next layer of powder being uneven and uneven, and even damaging the scraper. Physical process of interaction between laser molten pool and laser beam In order to keep the metal powder bed from being contaminated by spatter, a high-speed protective gas flow can be used to remove the spatter. However,6al4v titanium bar, excessive airflow will affect the surface quality of the powder layer, and how to optimize the airflow technology has become the direction of manufacturers'continuous efforts. 2. Spheroidization Expand the full text Spheroidization is a unique metallurgical defect in the manufacturing process of metal-based powder bed. Spheroidization occurs when the liquid metal solidifies into a spherical shape under the action of surface tension. If the laser beam energy density is too high or too low, it will lead to this phenomenon. If the energy is too low, the metal powder will not be completely melted, which will lead to spheroidization. If the energy is too high, the liquid metal will splash on the unmelted metal powder, which will also lead to spheroidization. Spheroidization will affect the quality of the next layer of powder,titanium filler rod, affect the surface quality of components, and also lead to defects such as poor fusion and slag inclusion. Further, ical paterials are more and more abundant, ti6al4v ,nickel titanium wire, and the mechanical properties of components have been greatlys to be manufactured through multiple layers, so each layer of powder is very important to the quality of the component. Powder spreading is the key step of SLM manufacturing, the quality of the powder layer is directly related to the absorption of the material to the laser, the thickness of the powder layer will affect the stability of the molten pool, too thick powder layer will cause defects such as lack of fusion, pores and so on,3d titanium wire, too thin powder layer will reduce the manufacturing efficiency, therefore, strictly controlling the quality of powder spreading is of great significance to improve the quality of SLM components. Return to Sohu to see more Responsible Editor:. yunchtitanium.com