Anticorrosion property enhancement of Al–Li alloy 2A97 by lowering machined surface roughness

In this study, after face‐milling Al–Li alloy 2A97 under dry machining condition, the machined surface roughness Sa and Sz are dealt with statistical analyses. Then, the supplementary face‐milling trials are conducted to verify the analyses and gain the effect of the feed rate per tooth (fz) on Sa and Sz. Lastly, the electrochemical impedance spectroscopy tests are conducted on the machined surfaces to determine their corrosion resistance. The variance analyses show that although fz and the depth of cut are more important than the width of cut and the cutting speed, each of the four parameters is individually insignificant to Sa and Sz. Therefore, the quadratic regression models that take the interaction effects of the parameters into consideration are established. The validity of the models is proved with the comparisons between the measured and calculated Sa and Sz. The equivalent circuit models are proposed on the basis of the shape characteristics of the impedance spectra for machined surfaces. The estimations from the circuit models reveal the superiority in the corrosion resistances of face‐milled surfaces with the optimized surface roughness.