Damage mechanisms in cavitation erosion of nitrogen-containing austenitic steels in 3.5% NaCl solution

• Published in: Wear Vol. 464-465; p. 203526
• Main Authors: Paolantonio, Mario, Hanke, Stefanie
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-01-2021; Elsevier Science Ltd
• Subjects: Austenitic stainless steels; Cavitation; Cavitation erosion; Corrosion; Corrosion effects; Damage; Distilled water; Ductile fracture; Erosion-corrosion; Exposure; Fatigue; Metal surfaces; Microscopy; Microstructure; Nitrogen; Pitting (corrosion); Plastic deformation; Sodium chloride; Stainless steel; Synergy effect; Work hardening; Fatigue; Work hardening; Plastic deformation; Corrosion; Microstructure; Synergy effect
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2020.203526

Interruptions of the passive layer of stainless steels by cavitation erosion expose the bare metal surface to the environment and can lead to cavitation-erosion-corrosion damage and synergistic effects. However, the probability for pitting corrosion is decreased during cavitation exposure of stainless steels in chloride solutions because mechanical passive film removal shifts corrosion potentials to lower cathodic values. In this study, the impact of 3.5 wt% NaCl in water on mass loss and damage features of two austenitic stainless N-containing steels is investigated to amend the understanding of cavitation erosion of passivating steels. Ultrasonic cavitation tests were carried out on steels 316LVM and CNMo0.95 in distilled water and 3.5% NaCl solution. Exposed surfaces were characterized qualitatively by light- and electron-microscopy and quantitatively by confocal microscopy. Damage mechanisms vary between the two steels but not with NaCl content in the solution. 316LVM also displayed the same mass loss in both solutions. CNMo0.95 possesses twice the strength as 316LVM, resulting in lower intensities of ductile damage mechanisms and slower damage progression. Mass loss of CNMo0.95 was lower in 3.5% NaCl solution compared to distilled water, which was primarily assigned to the effect of the salt content in the water on cavitation bubble formation.
•Changes in microstructure are shown by confocal microscopy after cavitation.•No indicators for corrosive damage such as pitting corrosion were found.•Nitrogen steels show different capabilities to absorb same cavitation impact damage.•Effect of salt content in water on cavitation bubble formation may reduce mass loss.