Cavitation erosion behavior of high-nitrogen austenitic stainless steel: Effect and design of grain-boundary characteristics

An understanding of the cavitation erosion behavior and mechanisms of high-nitrogen austenitic stainless steel is of interest for scientific and economic reasons. The original microstructure of 18Mn18Cr0.6 N steel was examined using electron backscatter diffraction analysis. Specimens were eroded using an ultrasonic cavitation erosion facility. The damaged surfaces were observed using scanning electron microscopy. Coherent 3 boundaries had the worst cavitation erosion resistance; the cavitation damage was located primarily at the same sides of the twins with a low Taylor factor. The cavitation erosion resistance decreased in the order: random high-angle grain boundaries and 27 boundaries; incoherent 3 boundaries; 9 boundaries; and coherent 3 boundaries. The Taylor factor was important in the analyses of metal material cavitation erosion. A large difference between the two grains or twins in the Taylor factor yielded a higher cracking risk of the boundary between them. Grain rotation led to a step formation at a boundary and the cavitation damage was accelerated. Three types of cavitation erosion were identified. A cavitation mechanism model for coherent 3 boundaries was proposed. Finally, the design of grain-boundary characteristics to improve the cavitation erosion resistance was discussed. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The study investigated the cavitation erosion behavior and mechanisms of high-nitrogen austenitic stainless steel, revealing the significant influence of grain-boundary characteristics on cavitation erosion resistance. A large difference in Taylor factor between grains or twins was found to increase the risk of cavitation-induced cracking.