Susceptibility to Pitting and Environmentally Assisted Cracking of 17-4PH Martensitic Stainless Steel Produced by Laser Beam Melting

Materials produced by additive manufacturing (AM) often have different microstructures from those obtained using conventional metallurgy (CM), which can have significant impacts on the materials’ durability, and in particular, resistance to corrosion. In this study, we were concerned with the suscep...

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Bibliographic Details
Published in:Materials 2022-10, Vol.15 (20), p.7121
Main Authors: Guennouni, Nizar, Maisonnette, Daniel, Grosjean, Christophe, Poquillon, Dominique, Blanc, Christine
Format: Article
Language:English
Subjects:
Agreements
Austenite
Corrosion and anti-corrosives
Corrosion resistance
Corrosion tests
Crack initiation
Crack propagation
Engineering Sciences
Environmentally assisted cracking
Fracture surfaces
Laser beam melting
Lasers
Manufacturing
Martensitic stainless steels
Materials
Metallurgy
Microstructure
Niobium carbide
Pitting (corrosion)
Propagation
Residual stress
Stainless steel
Steel, High strength
Steel, Stainless
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Summary:Materials produced by additive manufacturing (AM) often have different microstructures from those obtained using conventional metallurgy (CM), which can have significant impacts on the materials’ durability, and in particular, resistance to corrosion. In this study, we were concerned with the susceptibility to pitting and environmentally assisted cracking (EAC) of 17-4PH martensitic stainless steel (MSS). We focused on the evolution from pitting to EAC, and the behaviour of MSS produced by AM was compared with that of its CM counterpart. Potentiodynamic polarisation tests were combined with chronoamperometry measurements performed without and with mechanical loading to study both stable and metastable pitting and the influence of stress on these processes. EAC tests were carried out and combined with observations of fracture surfaces. MSS produced by AM was more resistant to pit initiation due to fewer and finer NbC particles. However, the propagation kinetics of stable pits were higher for this MSS due to a higher amount of reversed austenite. The stress was found to stabilise the metastable pits and to accelerate the propagation of stable pits, which resulted in an increased susceptibility to EAC of the MSS produced by AM. These results clearly highlighted the fact that the reversed austenite amount has to be perfectly controlled in AM processes.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma15207121