Abstract: A nanocrystalline surface layer is fabricated on 0Cr18Ni9Ti stainless steel and 16MnR low alloy steel welded joint by using a supersonic particles bombarding(SSPB) technology. The microstructure and surface structure of the material surface are analyzed by means of metalloscope, transmission electron microscope and X-ray diffraction. The hardness variation along the depth of the treated sample is examined as well. It is showed that after the SSPB treatment for a short time, the initial coarse-grained structure in the top surface layer is refined, and the average crystal dimension is 22 nm and 20 nm. The surface structure is homogeneous. At the same time, the hardness of nanostructured surface layer is enhanced significantly after the SSPB treatment. Compared with the core, the surface layer hardness enhances at least two times.

Key words: Surface nanocrystallization, Microstructure, Supersonic particles bombarding