Surface profiling of low-carbon steel with supersonic waterjets

In the paper, the authors investigate the capability of high-speed waterjets with velocities up to 700 m/s for the surface preparation of low-carbon steel. The problems associated with grit-blasting are reviewed, including grit contamination and the corresponding adhesion problems. Surface quality features of waterjetted surfaces are investigated; this includes average surface roughness, Rockwell hardness, surface microstructure, and wettability. The influence of several process parameters, such as jet velocity, jet impact energy and exposure time on process efficiency and surface quality are also investigated. It is found that waterjetting is capable of generating a high surface roughness. A general relationship between roughness and wettability of the generated surfaces is found; however, this is true only if a certain exposure time is exceeded. Waterjetting causes a notable increase in the Rockwell hardness. The higher the specific material removal, the higher the hardness. The specific material removal is linearly related to the kinetic energy of the impacting waterjet.