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Examining the Relationship Between Post-Build Microstructure and the Corrosion Resistance of Additively-Manufactured 17-4 Stainless Steel

Published

Author(s)

Mark R. Stoudt, Richard E. Ricker, Carelyn E. Campbell

Abstract

The performance of wrought and post-build heat treated, additively manufactured SS17-4 stainless steel was evaluated to determine whether additive processing can produce material that exhibits a corrosion resistance similar to that of a wrought alloy, and to establish whether the AM processing conditions alter the electrochemical conditions required for corrosion attack. Samples built by laser powder bed fusion (LPBF) from nitrogen-atomized and argon-atomized powder were heat treated achieve a homogenized, solutionized martensitic microstructure. The wrought alloy sample was also solutionized to minimize the influence of Cu precipitates. Multicomponent E-pH diagrams were constructed using equilibrium thermodynamic data and the three alloy compositions for a chloride containing environment to elucidate the nature of the chemical reactions that can occur in the SS17-4 alloy system and to indicate the regions where variations in passivity would be expected. Electrochemical measurements compared the behavior under free corrosion conditions and the pitting resistance of the three compositions in the chloride environment with differing solution pH levels. Analyses of the measurement data and the thermodynamic modeling revealed that the performance of the nitrogen-atomized alloy was a) greater than that of both the wrought and the argon-atomized alloys in a neutral pH, b) similar to that of the wrought in a moderately acidic solution, and c) generally better than that of the argon-atomized alloy. The results also revealed that at electrode potentials near Epit, dissolution of the nitrogen containing matrix suppressed the activity of CuCl3-2 in the solution and enhanced the activity of NH+4 ions, which signifies that the ionic phases at the surface of the electrode are dependent on the alloy composition.
Citation
Materialia
Volume
22

Keywords

Additive Manufacturing, Microstructure, Stainless Steel, Performance, Equilibrium Thermodynamics, Electrochemistry, Corrosion, Pitting

Citation

Stoudt, M. , Ricker, R. and Campbell, C. (2022), Examining the Relationship Between Post-Build Microstructure and the Corrosion Resistance of Additively-Manufactured 17-4 Stainless Steel, Materialia, [online], https://doi.org/10.1016/j.mtla.2022.101435, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933012 (Accessed May 24, 2024)

Issues

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Created May 1, 2022, Updated November 29, 2022