A novel controlled impact process for the formation of nanostructured surface in AISI304 stainless steel

A novel surface modification process for the development of nanocystalline structure on the metallic surfaces using a controlled ball impact concept is developed. A ball makes the controlled impacts on the sample surface, moved precisely by digitally controlled drives, during treatment. Preliminary studies were carried out on AISI304 stainless steel samples. An analytical model is followed to arrive at the ball diameter and impact velocity required for obtaining the nanocystalline structure in metallic mateirals. The treated specimens characterized using X-ray diffraction (XRD) and transmission electron microscope (TEM) revealed the formation of nanocystalline structure. Nano sized grains with an average grain size of 10 ± 2 nm were formed on the surface. The grain size formed by the process depends on the sample travelling velocity, which controls the coverage and heat generation.