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Laser powder bed fusion (LPBF) process allows to manufacture customized metal porous 3D parts known to have many interesting combinations of physical and mechanical properties. Therefore, the minimum resolution obtainable by this process is of high importance in the design of porous functional parts e.g. thin walls. Knowledge of the relationship between process parameters and material employed is fundamental to obtain these kinds of structures with LPBF. A series of experiments were carried out with a laser-melting system with laser power up to 200 W and a spot of 100 μm to analyze the influence of the manufacturing strategy in the construction of thin walls in AlSi10Mg alloy. The results showed that it is possible to have well defined dense thin walls using appropriate building strategies, providing also useful information for the design rules definition of the LPBF process. The results also showed that the energy density is not able to provide information on the complexity that involves the melt pools formation and propagation. A mathematical model was also developed to build well defined thin walls directly through the process parameters and to reduce the mismatch between as-designed and as-manufactured thin wall structures. The verification of such model was made building thin walls in AlSi10Mg and then comparing them to the as-designed structures. [ABSTRACT FROM AUTHOR]

Abstract Laser powder bed fusion (LPBF) is one of the most widespread additive manufacturing (AM) technologies for metals, in which the components are built additively layer upon layer along the z-axis (the building direction) perpendicular to the building platform (xy-plane). Here, we evaluated the effect of post-processing heat treatments at 200, 300, and 400 °C on the corrosion resistance of AlSi10Mg alloy manufactured by LPBF for two orientations in the building chamber (XY – parallel to the building plane or XZ – perpendicular to the building plane). Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests were conducted at the constant chloride ion concentration of 0.02 M and 23 °C for the as-built and heat-treated specimens. All specimens were polished on the surface and displayed similar behaviors in the EIS tests. The pitting potential results were widely scattered and therefore analyzed using a statistical approach. Statistical data analysis based on analysis of variance technique (ANOVA) was performed. The results confirmed that the population significantly differs only by considering the heat treatments and the building direction plays only minor role. The cumulative distribution curves of pitting potentials showed a decrease in pitting resistance as the temperature of heat treatment increases. Graphical abstract Effect of heat treatment temperature on the pitting potentials of AlSi10Mg obtained by means of laser powder bed fusion. Image 1 Highlights • Pitting potentials of AlSi10Mg present a wide experimental variability. • Cumulative frequency of pitting potentials shows a deleterious effect of the temperature of post-processing heat treatment. • Corrosion attack take place at the edge of melt pool up to 300 °C of heat treatment temperature. [ABSTRACT FROM AUTHOR]

Additive manufacturing has emerged as a promising method for developing new Ti-based alloys. However, very few works have been dedicated to the in-situ synthesis of Ti-Cu alloys using Laser powder bed fusion (LPBF) method. The current work investigates the correlations between the volumetric energy density (VED) and some structural features of the in-situ Ti-5 wt.% Cu alloys produced by LPBF of the elemental powders. The results highlighted the importance of selecting the size of constituents in accordance with their thermophysical properties. It was also shown that crystallite size and lattice distortion of the α phase increased with increasing the VED. These were attributed to the higher temperature and lower cooling rate of the melt pools as well as improved particles melting and copper dissolution in the titanium lattice at higher VEDs. Isotropy of the microstructure was also improved at higher VEDs. Image 1 • In-situ Ti-5%Cu alloy was produced by Laser Powder Bed Fusion of elemental powders. • Correlations between Volumetric Energy Density and microstructures were investigated. • Crystallite size and lattice distortion of α phase increased with increasing VED. • Isotropy of the microstructure was improved at higher VEDs. • Constituents size must be chosen in accordance with their thermophysical properties. [ABSTRACT FROM AUTHOR]