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The number of studies on the process parameter development for commercial pure titanium (Cp-Ti) with the L-PBF process is also quite limited in the literature. Laser powder bed fusion (L-PBF) process parameters can be changeable depending on the part geometry due to thermal conductivity differences. This paper summarizes the causes of powder adhesion from the perspective of the process involved in additive manufacturing, expounds the influence of different processes on the powder adhesion of titanium alloy forming parts, introduces the mainstream methods of powder sticking removal and summarizes the application of the additive manufacturing of titanium alloy in the medical field, which provides a theoretical basis for further development of the application of titanium alloy additive manufacturing technology in the medical industry. However, in the process of additive manufacturing and printing titanium alloys, there are often cases where the powder is not completely melted or the powder adheres to the product structure after printing, which introduces new biological risks. Therefore, it is widely used in the medical industry. It has excellent biocompatibility and can promote the growth and regeneration of bones in its interior. Titanium alloy is non-toxic and harmless in the human body. With the development of technology, custom orthopedic implants could be produced for different patients. Originally, it was only used as an innovative resource for prototypes.

Metal additive manufacturing (metal-AM) technology has made significant progress in the field of biomedicine in recent years. The results show that the optimized geometrical features of the track, together with the best microstructural and hardness properties, were obtained with the highest values of the laser energy input. Four sets of process parameters, considering different values of laser power, scanning speed, and powder feed rate, were selected in the manufacturing strategy, and specimens drawn from each single-track deposition were analyzed by stereomicroscopy, optical microscopy (OM), scanning electron microscopy (SEM-EDS), and X-ray diffraction (XRD). In the present investigation, the effect of different process parameters on geometrical features, quality, microstructure, and microhardness of 17-4 PH stainless steel single tracks deposited onto an AISI 316L stainless steel substrate was investigated. DED enables the manufacture of complex parts without using costly and time-consuming conventional processes, even though building parameters need to be accurately determined. Besides improving the understanding of the keyhole phenomenon, the proposed model may provide a novel, effective and simple tool for fast process parameter optimization in industry.ĭirect energy deposition (DED) is a widely accepted additive manufacturing process and a possible alternative to the subtractive manufacturing processes due to its high flexibility in fabricating new 3D parts. The comparison between experimental data and model predictions confirmed the higher accuracy of the new model with respect to state of the art models. Produced samples were cross-sectioned and analyzed to evaluate keyhole porosity formation.

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The proposed model was validated by performing single tracks experiments on Ti6Al4V according to a full factorial DoE on laser power and scanning speed. Here an innovative physics-based semi-analytical model for predicting the formation of keyhole-related porosities was conceived, in which both thermodynamic and geometrical factors are taken into account. In this work, state-of-the-art analytical models for predicting keyhole porosity were summarized and proved to be rather inaccurate because they are only based on thermodynamic principles, whereas they neglect the geometry and both the kinetics and kinematics of the keyhole cavity, which do also influence cavity collapse and porosity formation. To date, keyhole-free process parameters can be identified either using demanding empirical methods or complex numerical simulations, while only a few analytical models can be found in literature for this purpose.

When performing Laser Powder-Bed Fusion, undesired physical phenomena, such as balling, preballing and keyhole, must be avoided in order to achieve high-quality products.

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