Study on Corrosion Behavior of as-forged AZ81 Mg alloy in different concentrations of NaCl solution

Abstract

In this paper, the microstructure of as-forged AZ81 Mg alloy before and after heat treatment was analyzed by means of optical microscope and XRD, the corrosion behavior of as-forged AZ81 Mg alloy after heat treatment with different concentrations of NaCl solution was studied by static immersion weight loss method. The results show that: after solution aging heat treatment at 400°C×0.5h+200°C×20h, the grain size of the alloy is more uniform, but the effect on the average grain size is not obvious; when the corrosion time is fixed, the corrosion rate of as-forged AZ81 Mg alloy increases rapidly with the increase of NaCl concentration; with the extension of corrosion time, the corrosion rate of as-forged AZ81 magnesium alloy increases in a fluctuating manner, and then in a fluctuating decreases after reaching the peak value, and after 72h of etching, the corrosion rate of the alloy is basically unchanged; meanwhile, the corrosion in as-forged AZ81 magnesium alloy shows obvious filamentous propagation characteristics, and these filamentous corrosion characteristics basically extend and distribute along the grain boundary.