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Understanding the Influence of Surface Condition on the Fatigue and Corrosion Fatigue Behavior of SLM718

Selective laser melting (SLM) is a widely used additive manufacturing (AM) process, also for producing components using precipitation-hardenable nickel alloy 718 (UNS N07718). SLM has been largely accepted into many industries including oil and gas (O&G) with current research efforts focused on demonstrating materials performance in demanding applications including directional drilling and reservoir characterization tools. A broader applicability of additively manufactured UNS N07718 in such applications is currently conditioned by characterization efforts limited to corrosion testing on machined surfaces, which are not representative of the surface resulting from SLM process. The lack of understanding regarding the influence of as-printed surface conditions for UNS N07718 produced via SLM on fatigue and corrosion fatigue limits its applicability to the machined surface condition, thus negating benefits gained during the manufacturing process. In this research work, the fatigue and corrosion fatigue behavior of additively manufactured UNS N07718 in as-printed conditions was investigated. Besides fatigue in air at ambient temperature, corrosion fatigue of SLM718 was tested in alkaline 5 M chloride-containing brines at 125 °C to simulate a typical drilling environment. Experimental results have shown that as-printed surfaces of SLM718 are significantly more prone to fatigue and corrosion fatigue compared to machined surfaces. Besides increased surface roughness the presence of near-surface defects typical of AM can be seen as the reason for the observed fatigue behavior.
Product Number: 51324-21234-SG
Author: Helmuth Sarmiento Klapper; Nils Holzapfel; Wei Chen; Juan Carlos Flores
Publication Date: 2024
$40.00
$40.00
$40.00