Effect of unit cell size and geometry on localized corrosion of laser powder bed fusion 316L lattice structures

An open dataset for the paper with the same title: "The Effect of Unit Cell Size and Geometry on Localized Corrosion of Laser Powder Bed Fusion 316L Lattice Structures".

The dataset contains, for example, 3D models, original and analyzed microCT data, video visualizations, tensile testing .csv files, microscopy images, and code resources. Selected works are presented as part of the paper.

Abstract:

Laser powder bed fusion (L-PBF) has become an established method in the manufacture of end-use metal components. Exploiting the geometrical freedom of additive manufacturing (AM) with lattice structures offers broad possibilities for part optimization and enables performance increases across industry sectors. However, part shape and feature size have been found to locally affect residual stresses, melt pool cooling rates, microstructure, and thus the mechanical properties of components. There are no prior studies on the influence of feature size and shape on corrosion. Using AM parts in critical applications necessitates a better understanding of how optimized parts perform long-term in demanding environments. The paper studies the lattice unit cell size- and shape-dependence on corrosion susceptibility and its spatial localization.

The susceptibility of submillimeter L-PBF 316L stainless steel lattice structures to localized corrosion is investigated with a 21-day immersion corrosion test (aqueous 3.5wt% NaCl solution). Schoen Gyroid and Schwarz Diamond triply periodic minimal surface (TPMS) lattices are manufactured in three unit cell sizes and wall thicknesses (0.867 mm, 0.515 mm, and 0.323 mm). The nominal surface and cross-sectional areas are kept equivalent between the two geometries. Before and after computed tomography scans are analyzed for volumetric losses, and the mechanical properties of samples are evaluated in contrast to references found in the literature. The digital workflow of the study with open-source software is fully disclosed.

Three out of five of the 0.322 mm wall thickness lattices displayed visually aggressive pitting. Based on microcomputed tomography data, the mass losses were localized either in entrapped powder particles or partially melted surface globules. Corrosion was not found to proceed to the dense base material. Total mass losses ranged from 8 to 19 milligrams. Despite visual indications to support higher susceptibility for smallest lattice sizes, the mass loss values did not confirm the conclusion. The tensile testing results provided weak indications of latent corrosion effects on the mechanical properties of samples.