In the automotive industry, mechanical grinding is employed at finishing line rectification to remove defects left over from upstream, which may also result in microstructure modification within the near-surface region of the work piece and, consequently, affects its corrosion performance. The present work investigates the influence of mechanical grinding on the microstructure modification and corrosion behaviour of Al-Si-Mg (A356) alloy castings in order to advance the understanding of potential corrosion issues. It is found that a near-surface deformed layer with a maximum thickness of 3 μm, characterised by ultrafine equiaxed grains of 50-150 nm diameter, is introduced by the grinding process on α-aluminium matrix. The near-surface deformed layer has a significant impact on the corrosion behaviour of the alloy; specifically, preferential dissolution of the near-surface deformed layer occurs when exposed to NaCl solution, together with trenching of the aluminium matrix around the eutectic silicon particles.
|Journal||Corrosion Engineering, Science and Technology|
|Publication status||Accepted/In press - 10 Oct 2021|