An experiment-based investigation on surface corrosion resistance behaviors of aluminum alloy 7050-T7451 after end milling

Abstract

High-strength aluminum alloys are widely used in the aeronautic industry because of their excellent combined performance including good corrosion resistance. In this paper, an experiment-based study on the surface characteristics is presented including residual stress and surface defects induced by end milling processes. Salt-spray corrosion tests are carried out on the end machined surfaces and corrosion morphologies during different corrosion periods are achieved. Observations from microscopy and energy dispersive X-ray spectrometer (EDS) analysis support the existence of micro-cracks, leading to occluded corrosion cells, which accelerate the corrosion. It is found that residual stress, micro-cracks and their combination are important to the corrosion resistance performance of machined aluminum alloy parts. Experiments show that while feed speed v_f = 750 mm/min and rotational speed n = 4500 rpm, larger compressive stresses and lower corrosion depths are achieved.