On the Anisotropic Mechanical Properties of Selective Laser-Melted Stainless Steel

TLDR

Additive manufacturing, particularly selective laser melting, enables rapid, tool‑free fabrication and design flexibility, yet demands precise knowledge of anisotropic, inhomogeneous material properties that depend on process parameters. This study measures the anisotropic tensile properties of SLM 316L stainless steel, reporting Young’s modulus (148–227 GPa), ultimate tensile strength (512–699 MPa), and elongation (12–43 %). The authors compare their results with related work to evaluate the influence of fabrication settings and raw material, examining directional dependencies arising from microstructural variations during build. The material shows maximum strength at a 45° layer‑to‑loading orientation, opposite to AlSi10Mg, which is weakest at that angle.

Abstract

The thorough description of the peculiarities of additively manufactured (AM) structures represents a current challenge for aspiring freeform fabrication methods, such as selective laser melting (SLM). These methods have an immense advantage in the fast fabrication (no special tooling or moulds required) of components, geometrical flexibility in their design, and efficiency when only small quantities are required. However, designs demand precise knowledge of the material properties, which in the case of additively manufactured structures are anisotropic and, under certain circumstances, inhomogeneous in nature. Furthermore, these characteristics are highly dependent on the fabrication settings. In this study, the anisotropic tensile properties of selective laser-melted stainless steel (1.4404, 316L) are investigated: the Young's modulus ranged from 148 to 227 GPa, the ultimate tensile strength from 512 to 699 MPa, and the breaking elongation ranged, respectively, from 12% to 43%. The results were compared to related studies in order to classify the influence of the fabrication settings. Furthermore, the influence of the chosen raw material was addressed by comparing deviations on the directional dependencies reasoned from differing microstructural developments during manufacture. Stainless steel was found to possess its maximum strength at a 45° layer versus loading offset, which is precisely where AlSi10Mg was previously reported to be at its weakest.