Study on the cavitation erosion behavior and mechanism of nanostructured bainitic steel

Le résumé fourni par la source

In this study, martensitic steel, lower bainitic steel, and nanostructured bainitic steel were fabricated from the same bearing material (GCr15SiMoAl) using three distinct heat treatment processes. Under identical cavitation erosion (CE) test conditions, the mean depth of erosion (MDE) of the nanostructured bainitic steel was 81 % and 49 % of that of the lower bainitic steel and martensitic steel, respectively. Correspondingly, its erosion rate (ER) was only 79 % and 48 % of that of the lower bainitic steel and martensitic steel, while the incubation period of CE was 1.36 and 2.74 times that of the lower bainitic steel and martensitic steel, respectively. These results unequivocally demonstrated that the nanostructured bainitic microstructure conferred superior cavitation resistance, enabling the bearing steel to retain exceptional surface integrity even after prolonged exposure to cavitation attack. This outstanding performance stemmed from the synergistic effect of uniformly distributed surface compressive residual stresses and the intrinsic stability of the constituent phases. Additionally, all three steels exhibited similar damage mechanisms: cavitation damage initiated in the form of micropores or microcracks and subsequently propagated along directions of maximum stress concentration.

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