Comparison of Additively Manufactured vs. Conventional Maraging Steel in Corrosion-Fatigue Performance after various surface treatments
E. Bouzakis, Apostolos Arvanitidis, Fotis Kazelis, G. Maliaris, Nikolaos Michailidis
Abstract
Additive manufacturing (AM) exhibits some inherent processing characteristics that affect the grain structure, phase formation, microstructure, roughness and porosity, compared to conventionally manufactured components. Consequently, the surface originating functional life, especially corrosion, can be severely affected.The present study highlights and compares the fatigue life of maraging steel 18Ni-C300 (1.2709, X3NiCoMoTi18-9-5) obtained by the SLM-fabricated specimens with the corresponding ones machined to the same geometry from a rolled bar. Metallography, microscopy, surface scanning, FEM and hardness measurements were employed to help understand the results obtained. To make a more realistic estimation of the life expectancy, fatigue was performed both in a corrosion-free environment and in a typical 3.5% wt. NaCl aqueous solution. Additionally, the effect of glass- blasting (GB) performed as a post-treatment in the SLM specimens was investigated both. There is a clear superiority of the wrought material both in pure fatigue and in corrosion-fatigue, because of its dense and homogeneous microstructure as well as its lower resulting surface roughness. The AM material, due to multiple melt pools created from the consecutive laser passes, the cellular-dendritic structure and the inherent higher roughness they possess, has an inferior fatigue and corrosion-fatigue performance. Glass-blasting improves surface integrity by imposing residual stresses and reducing the roughness, both offering a positive impact on the corrosion and fatigue performance.