Improving Corrosion Resistance Properties of Nickel-Aluminum Bronze (NAB) Alloys via Shot Peening Treatment

In this paper, Nickel-Aluminum Bronze (NAB) alloy was subjected to the shot-peening (SP) treatment, and the corrosion resistance properties of SPed NAB alloy was systematically studied by scanning electron microscope, transmission electron microscopy, electrochemical workstation and immersion tests. The results show that SP treatment can improve the corrosion resistance properties of NAB alloy by controlling shot peening intensity. The SP treatment can result in rough surfaces, high-density dislocations and grain refinement of alpha and beta' A martensitic phases in NAB alloy surface. In the corrosion medium, the corrosion resistance properties of SPed NAB alloys are related to not only the surface microstructures but also the surface roughness. The refined and homogenized microstructures favors the rapid formation of the protective passive film and promotes the occurrence of uniform corrosion on shot-peened NAB alloy surface, thus significantly improving their corrosion resistance properties. However, as the shot-peening intensity exceeds a critical value, the higher roughness values due to the large cracks, chips and flaking appearing on the shot-peened sample surface can deteriorate corrosion resistance properties.