Experimental study and cellular automata simulation of corrosion behavior of ferritic stainless steel in molten aluminum

The corrosion behavior of ferritic stainless steel (446) after being immersed in molten Al alloy at 750 °C for 1, 2, 4, and 8 h has been investigated experimentally and theoretically. The microstructure and composition distribution at the corrosion interface were characterized using the optical microscope, scanning electron microscope, and energy dispersive spectrometer. The results showed that Cr and Si synergistically delay the progress of corrosion at the interface of the intermetallic compounds (IMC). In the early stage of corrosion, Si element was enriched at the interface of IMC1 and IMC2, and the diffusion channels of Al element were occupied by it. However, as the corrosion progresses, Cr and Si gradually gather to form a band-like structure and coarsen, causing their hindering effect to be weakened. As the corrosion time increases, the banded structure was further aggregated and coarsened, and the inhibitory effect of Cr and Si elements on corrosion was strongly weakened. In addition, based on the cellular automata dynamics model of reaction–diffusion, the corrosion process of ferritic stainless steel in aluminum alloy melts was simulated. It is demonstrated that if there is no stabilizing effect of Cr element, the thickness of IMC will be doubled.