A Novel Shock Processing by High-Intensity Pulsed Ion Beam

Abstract

A novel shock processing by high-intensity pulsed ion beam (HIPIB) is developed, referred to as ion beam shock processing (IBSP), for surface processing of components with high surface integrity. The IBSP utilizes effectively coupled thermal-dynamic effects of HIPIB irradiation onto materials, characterized by ultrafast surface remelting and solidification, and controlled ablation. As a result, using the IBSP treatment with HIPIB parameters with an ion energy of 200–400 keV and an ion current density of 50–400 A/cm2 with a pulse width of 75 ns, i.e., a power density of 107–108 W/cm2, hardening extending to tens and hundreds of micrometers in depth is achieved on pure Cu and 316L austenitic stainless steel, which is comparable to that of laser shock processing at about two orders higher power density, usually no less than 109–1010 W/cm2. Significant improvements in the overall performance including wear and corrosion resistance, fatigue, and creep properties are found for IBSP treated pure Cu and 316L stainless steel, attributable to the formation of nonequilibrium microstructures into different depths of the processed materials, e.g., amorphous and/or nanocrystalline structure in the heat-affected zone, and high-density defects in the deeper regions with residual compressive stresses caused by shock wave propagation into substrate in which the former is not obtainable in conventional shock processing. Furthermore, purified and polished surfaces free of cracks can be obtained simultaneously under HIPIB irradiation, composing the completeness for effectively enhancing the surface integrity of the processed materials. The coupled thermal-dynamic effects of IBSP assure surface processing of high surface integrity for components, with improved physical and chemical properties and modified surface topography.