CAVITATION EROSION OF ION-IMPLANTED 1018 STEEL.

The mechanical damage produced by ultrasonic cavitation erosion in 75 keV nitrogen-implanted 1018 steel (0. 18% C) was studied using weight loss measurements and scanning electron microscopy observations. Total weight loss curves were obtained for three different conditions as a function of exposure time. The results indicate that there is an incubation period prior to damage which is prolonged by a factor of about 1. 5 through ion implantation alone and by a factor of 3 through ion implantation followed by thermal aging. A roughened surface topography was observed to evolve for continued cavitation exposure. The increase in incubation time and the changes in the topographical features are discussed in terms of the formation of nitride when the steel is nitrogen implanted and aged.