Surface nanocrystallization of AISI-1018 steel was successfully realized by ultrasonic shot peening (USSP). The fabricated nanocrystalline surface layer was observed and characterized by means of scanning electron microscope and transmission electron microscope. Experimental evidence indicates that after USSP, the initial coarse-grained structure (~20 µm) at the top surface layer was refined into ultrafine grains with random crystallographic orientation and the elongated grains were observed at the sub-surface layer. Nanograins (~100 nm) and nanocrystalline surface layer with the thickness of 1 µm were fabricated after USSP treatment of 20 minutes. By increasing the USSP treatment duration to 60 minutes, nanograins in the size of 20 nm and nanocrystalline surface layer with the thickness of not less than 10 µm were generated. To predict the generation of nanostructured surface layer by plastic strain, an analytical algorithm cooperating with finite element method was proposed to simulate the strain distribution and surface topography of the peened surface during USSP. The proposed algorithm was verified and the simulation results show a reasonable agreement with the experimental results.
|Number of pages||9|
|Journal||Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science|
|Publication status||Published - 2014|
ASJC Scopus subject areas
- Condensed Matter Physics
- Metals and Alloys
- Mechanics of Materials