Cavitation erosion mechanism of 2Cr13 stainless steel

Abstract

The erosion mechanism of 2Cr13 stainless steel under ultrasonic cavitation was investigated. The cavitation erosion process investigated in this paper included the incubation period and acceleration period. Microhardness measurement and transmission electron microscopy showed that the surface was deformed and hardened, the grains on the eroded surface layer were refined by nanograins and subgrains. Scanning electron microscopy and electron backscatter diffraction analysis showed that cracks were initiated at the grain boundaries and subgrain boundaries, pits were from the carbide-matrix interfaces and defect microholes, in the incubation period, cracks were grown across the grain into peelings, pits were connected into microholes. In the acceleration period, cracks were initiated at and propagated along the grain boundaries and subgrain boundaries. Kernel average misorientation (KAM) was utilized to show the strain at the grain boundaries and subgrain boundaries and to estimate the density of the geometric necessary dislocations (GNDs) along the depth after cavitation erosion. The thickness of the strain layer after cavitation erosion was not more than 23 μm. The surface fatigue failure was caused by the plastic deformation and stress concentration under the continuous cavitation impacts.