Additive manufacturing (AM) has recently become an increasingly popular form of production due to its advantages over traditional manufacturing methods, such as accessibility, the potential to produce parts with complex geometry, and reduced waste. For the widespread industry adoption of AM components, metal AM has the most potential. The most popular methods of metal AM are powder-based manufacturing techniques. Due to the layer-by-layer nature of AM, the mechanical and tribological properties of an additive manufactured part differs from those of traditionally manufactured components. For the technology to develop and grow further, the tribological properties of AM components must be fully explored and characterized. The choice of material, surface textures, and post-processing methods are shown to have significant impact on friction and wear. Therefore, this paper focuses on reviewing the existing literature with an emphasis on the development of advanced materials for AM applications as well as the optimization of the resulting surface quality via post-processing and presents areas of interest for further examination in this prospective technology.

https://www.mdpi.com/2504-4494/6/6/138/pdf?version=1668159997

Tribological Behavior of Additively Manufactured Metal Components

Utilization of L-PBF process for manufacturing an in-situ Fe-TiC metal matrix composite

Utilization of L-Pbf Process for Manufacturing an In-Situ Fe-Tic Metal Matrix Composite

In this work, three-dimensional stainless steel 316L re-entrant lattice structures were fabricated by two mainstream powder bed fusion (PBF) techniques, namely electron beam PBF (EB-PBF) and laser PBF (L-PBF). Different grain morphology and crystallographic textures were found in the EB-PBF and L-PBF samples, which significantly influenced their mechanical properties through microscopic deformation. The EB-PBF and L-PBF samples achieved energy absorption capacities of 627.4 mJ/mm3 and 834.8 mJ/mm3, respectively, at a lattice relative density of ∼24%. The EB-PBF sample exhibited equiaxed and elongated grains, while elongated grains were primarily observed in the L-PBF sample. The dominant deformation mechanism of the EB-PBF sample was obtained through dislocation. In contrast, the dislocations trapped inside the solidification cellular walls and deformation-induced twinning were the dominant deformation mechanisms for the L-PBF sample, which contributed to its superior compressive strength and energy absorption capacities. This work provides insights into the enhancement of the mechanical properties of the additively manufactured metallic lattice structures through microstructural control. 

Influence of microstructure on stainless steel 316L lattice structures fabricated by electron beam and laser powder bed fusion

The aim of this study is to investigate and benchmark the physical and elastic properties of strut-based lattice structures produced by selective laser melting from 316L stainless steel material, which has many uses in various sectors. Within the scope of the presented study, the relative density and relative elastic modulus for 27 types of strut-based lattice structures of different sizes with simple cubic (SC), body-centered cubic (BCC) and face-centered cubic (FCC) geometry were evaluated and compared. Numerical analyzes were utilized due to the evaluated design and dimensional configuration diversity, and consistent results were obtained with the studies published in the previous literature. The findings of the study showed that for all lattice structure types, volume fraction increases with the increasing diameter and decreases with the increasing cell size. With the utilization of same strut diameter and cell size FCC type lattice structures exhibit the highest volumetric fill while SC type lattice structures exhibit the lowest. The increase in the volume fraction increases the relative elastic modulus. For the same volume fraction, SC lattices represent the highest relative elastic modulus while FCC lattices indicate the lowest. 

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Numerical Investigations and Benchmarking of The Physical and Elastic Properties of 316L Cubic Lattice Structures Fabricated by Selective Laser Melting

Combining the geometrical freedom provided by laser powder bed fusion (L-PBF), a powder bed fusion additive manufacturing (AM) process, and tailoring the mechanical properties by the use of lattice structures, many applications benefit from lightweight lattice structures such as aerospace and biomedical. Many different aspects of the lattice structures produced by L-PBF have been addressed in the literature including weight reduction, energy damping, compression behavior, manufacturability, and surface characteristics. Although lattices are seen as a promising design tool, the influence of using lattices inside the part surface on the wear behavior of L-PBF specimens has not yet been addressed in the literature. In this study, the effect of different lattice structures varying in unit cell geometry and size, built along different directions on the wear behavior, is addressed using AISI 316L powder processed with L-PBF. Moreover, to understand the wear behavior in detail, microhardness and compression testing of the samples were accomplished. As a result, it is found that the microhardness measurements change by only 5% on different build directions, whereas the lattice type is a significant factor regarding the modulus of elasticity and absorbed energy per unit volume. Moreover, it is concluded that although the coefficient of friction has an average value of 0.7, it does not vary depending on the tested factors, whereas the specific wear rate is influenced by the build direction and part geometry. Thus, for applications where tribological properties are important, the effect of heat dissipation and cooling rate leading to microstructural changes needs to be considered when utilizing L-PBF.

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Papers

Tribological and mechanical behavior of AISI 316L lattice-supported structures produced by laser powder bed fusion