Ultrasonic surface shot peening (USSP) treatment was conducted on the WC-8Co composite. The effects of different USSP-treated time on surface roughness, microstructure, mechanical and corrosion resistance were investigated. The results show that continuous bombardment on the surface of WC-8Co cemented carbide induced by high kinetic energy particles during USSP makes the WC particles and Co phase broken and refined. A nanostructured layer is generated on the top-surface of WC-Co cemented carbide and the thickness is about 3.14 µm. Due to the polishing and washing of all samples, the results of surface roughness don’t change much. Microhardness of nanostructured surface layer increases by 15.8% compared with the untreated sample. Electrochemical experiment results indicated that the refinement of grain are the main reasons for the enhanced corrosion behavior of the samples. At the same time, the most suitable shot peening time of USSP for WC-8Co cemented carbide is 30 min.

Surface nanocrystallisation (SNC) was prepared on the top-surface layer of 304 stainless steel by ultrasonic surface rolling treatment (USRT). Meanwhile, martensite transformation also occurred during grain refinement, and the surface microhardness increased more than tripled after USRT. The corrosion resistance of nanocrystallines (NC) 304 stainless steel was notably better than that of untreated samples in simulated pressurised water reactor (PWR) secondary water by potentiodynamic polarisation curves, electrochemical impedance spectroscopy and Mott-Schottky curves. Meanwhile, the corrosion mechanism was discussed before and after USRT by X-ray photoelectron spectroscopy (XPS). The main reason is due to the formation of denser Cr(OH)₃ protective film and the reduction of the porous structure Fe₂O₃ content in the NC 304 stainless steel.