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The Influence of Post-Build Microstructure on the Electrochemical Behavior of Additively Manufactured 17-4 PH Stainless Steel

Published

Author(s)

Mark R. Stoudt, Richard E. Ricker, Eric Lass, Lyle E. Levine

Abstract

The repetitive rapid solidification that occurs during additive manufacturing (AM) results in microstructures that deviate significantly from those observed in wrought materials with the same nominal composition. The result is a segregated microstructure with significant localized variations in composition, as well as phases that are improbable in traditional wrought materials. AM studies typically concentrate on refining the build process and the role of the post-build heat treatments, which are generally designed to relieve residual stresses generated during the build and do little to homogenize the microstructure. However, consideration of the full life-cycle performance of AM parts is a critical element for part qualification and the influence of the microstructural inhomogeneities is of particular concern. In addition, variability in the corrosion resistance of any stainless steel can be a performance-limiting factor that must be assessed. The microstructural inhomogeneities in AM materials are known to promote variability in the mechanical performance, but the influence of the post-build microstructure on the corrosion resistance is not as well understood. SS17-4PH is an industrially important alloy for applications that require high-strength and good corrosion resistance. This alloy also performs well during AM processing. In wrought form, SS17-4PH is typically a two-phase structure consisting of delta-ferrite stringers in a martensite matrix that can be heat treated to achieve a specific strength, but the as-built AM microstructure is often a mixture of alpha-ferrite and austenite that does not readily transform to martensite. This presentation describes a series of experiments designed to evaluate the influence of these microstructural differences on the electrochemical and corrosion behavior of SS17-4PH. The experimental design, the microstructures, and results for the wrought and AM-produced materials will be presented, compared, and discussed.
Citation
JOM Journal of the Minerals Metals and Materials Society
Volume
69
Issue
3

Citation

Stoudt, M. , Ricker, R. , Lass, E. and Levine, L. (2017), The Influence of Post-Build Microstructure on the Electrochemical Behavior of Additively Manufactured 17-4 PH Stainless Steel, JOM Journal of the Minerals Metals and Materials Society (Accessed November 26, 2022)
Created March 1, 2017, Updated March 10, 2017