Comparison Study on Machined Surface Integrity and Corrosion Resistance of 2024 Aluminum Alloy

Abstract

2024 aluminum alloy is an engineering equipment material with broad application prospects, which can be used in space flight and shipbuilding industry. However, the lack of corrosion resistance hinders its further application. The effects of milling and further shot peening processes on the surface integrity of 2024 aluminum alloy were investigated. Electrochemical polarization measurements were performed in 3.5wt% NaCl solution to characterize the corrosion resistance of milling alone surfaces and the further shot-peening process surfaces after milling. Experimental results reveal that the surface residual stress and microhardness of the shot-peened surfaces are much higher than those of the only milling surfaces owing to the severer plastic deformation induced by further shot peening process. While the shot-peened surfaces are roughened with the higher surface roughness. Under the synergic effects of three terms mentioned above, the corrosion potential of shot-peened surfaces is much positive than that of milled ones, meaning the corrosion resistance after shot peening is better. The comparison test gives a way to enhance the corrosion behavior of 2024 aluminum alloy milled surfaces.