The microstructure and mechanical properties of metallic parts produced by additive manufacturing are significantly influenced by processing parameters. For laser-based technologies, the laser beam shape introduces an additional variable, which can profoundly affect the crystallography orientation, microstructure, and phase composition of the final part. This study investigates the effects of a Gaussian laser beam profile on the microstructure and phase distribution in thin-walled 316L stainless steel samples fabricated by directed energy deposition (DED). Hollow cylinders fabricated with a single-bead deposition were cut in one position along the growth direction (YZ sample). Furthermore, additional cuts were performed in positions perpendicular to the building direction in order to extract two XY samples, one comprising the first deposited layers and the second one the final layers of the build job. Detailed characterization revealed that the Gaussian beam shape profile drives localized variations in phase composition, with a marked disparity in δ-ferrite content between the outer regions and the core of the walls. Furthermore, microhardness measurements along the printing direction indicate that lattice microstrain, rather than primary cellular arm spacing (PCAS), predominantly governs hardness levels.

The dislocation density in additive-manufactured components significantly influences the local mechanical behavior of crystalline metals. Nanoindentation, renowned for its sensitivity to local mechanical responses and hardness, facilitates the assessment of local dislocation density. This study aimed to analyze the evolution of local dislocation densities in bulk, graded lattice structures (GLSs), and reduced-size GLSs of LPBF SS316L via nanoindentation. Components were fabricated using laser powder bed fusion with 316L stainless steel. The microstructural analysis revealed that the distribution of mechanical deformation across the bodies of the parts was higher in the reduced-size GLS compared to that obtained for the GLS. The simulation of plastic deformation allowed for recognizing that this difference is attributed to the different thermal stresses resulting from the higher rate of thermal excursions to which the scaffold structure was subjected whenever there was a reduction in the reciprocal distance of the struts. Mechanical deformation, identified as the primary factor contributing to dislocation density in additive manufacturing, was significant in both the GLS and reduced-size GLS, for which the dislocation density was incremented by one order of magnitude compared to the bulk material.

This study explores the application of lattice structures as internal support architectures in the fabrication of Inconel 718 components via Laser Powder Bed Fusion (L-PBF), building upon previous research on beam-based FCCZ supports. Two representative lattice typologies were investigated: the node and beam-based FCCZ (face centered cubic with Z direction reinforcement struts) structure and the triply periodic minimal surface (TPMS) Schoen Gyroid cell. The aim was to assess how the transition from a discrete beam-node architecture to a continuous surface topology influences manufacturability, thermal stability, and mechanical performance. Finite Element Method (FEM) simulations in Ansys accurately predicted distortions and residual stresses during the L-PBF process, showing strong agreement with stereomicroscope measurements. Specifically, the maximum directional deformation reached 0.32 mm for the FCCZ sample versus 0.17 mm for the Gyroid, with corresponding peak residual stresses of 1328 MPa and 940 MPa, respectively. After fabrication, the samples underwent solution treatment and double aging according to AMS 2774 and AMS 5662 standards. Vickers microhardness increased from about 320 HV0.3 in the as-built condition to 500 HV0.3 after heat treatment (+55%), with overall porosity remaining below 1%. Microstructural analysis using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) revealed that heat treatment partially homogenized the microstructure but did not achieve complete recrystallization, leaving localized dendritic regions and undissolved Laves phases, particularly near the lattice. The precipitation of γ′ and δ phases enhanced hardness and mechanical uniformity, as confirmed by Vickers microhardness testing. Quantitatively, the Gyroid topology exhibited approximately 40% lower deformation and defect density than the FCCZ structure, confirming its superior manufacturability and thermal stability. These findings provide practical guidance for selecting lattice topologies for support architectures in L-PBF Inconel 718 components where thermal stability and shape preservation during build are critical.

Metallic mechanical metamaterials have attracted the attention of many industrial sectors due to their unique properties which enable them to outperform natural materials in unconventional ways. Metal metamaterials encompass multiple fields, including materials science, mechanics, and industrial technology, and they have become particularly popular following the implementation of reliable, high-resolution, efficient metal additive manufacturing processes. This review takes a joint approach, providing an in-depth analysis of the base materials and geometries that characterize metamaterials in order to understand their behavior in response to impacts at different load regimes and to offer readers a critical overview of the most suitable design choices for energy absorption systems. Furthermore, this review highlights advanced metamaterial optimization methods that are useful for increasing the mechanical energy absorbed avoiding peak impulse transfer to the people, instrumentation, or generic loads that mechanical metamaterials are designed to protect.

This study explores the application of lattice structures as internal support architectures in the fabrication of Inconel 718 components via Laser Powder Bed Fusion (L-PBF), building upon previous research on beam-based FCCZ supports. Two representative lattice typologies were investigated: the node and beam-based FCCZ structure and the triply periodic minimal surface (TPMS) Schoen Gyroid cell. The aim was to assess how the transition from a discrete beam-node architecture to a continuous surface topology influences manufacturability, thermal stability, and mechanical performance. Finite Element Method (FEM) simulations in Ansys accurately predicted distortions and residual stresses during the L-PBF process, showing strong agreement with stereomicroscope measurements. After fabrication, the samples underwent solution treatment and double aging according to AMS 2774 and AMS 5662 standards. Microstructural analysis using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) revealed that heat treatment partially homogenized the microstructure but did not achieve complete recrystallization, leaving localized dendritic regions and undissolved Laves phases, particularly near the lattice. The precipitation of γ′ and δ phases enhanced hardness and mechanical uniformity, as confirmed by Vickers microhardness testing. Overall, the Gyroid topology demonstrated superior manufacturability and thermal stability, exhibiting reduced defects and deformation compared to the FCCZ structure. These findings confirm its potential as an efficient and reliable self-supporting architecture for L-PBF Inconel 718 components intended for high-performance and thermally demanding applications.

• Fe-Mn thin structures (75–85 µm thick) were successfully electroformed using ethylene glycol-based DES. • Glycine addition enhanced Mn co-deposition and increased current efficiency (from 73 % to 88 %). • Higher glycine concentrations improved crystallinity and increased hardness up to 600 HV. • Addition of glycine to the electrolyte increased the corrosion rate from 0.4 up to 1.3 mm/yr.