Investigation on corrosion mechanism of stirring paddles of different iron-based materials in ZL101 aluminum melt

Aiming at the material selection of the stirring paddle in the mechanical stirring equipment, the corrosion mechanism of four different iron-based material stirring paddles when stirring the ZL101 aluminum alloy melt were studied. Using scanning electron microscopy (SEM), EDS and OM methods, the microstructures and phase compositions of the reaction layers formed by the corrosion of the ZL101 melt in the four iron-based stirring paddles of A3 steel, heat-resistant stainless steel 1.4837, QT5381 and HT300 during the stirring process were analyzed. The experimental results show that the microstructures and phase compositions of the reaction layers of the A3 steel, QT5381, HT300 had certain similarities, and the heat-resistant stainless steel 1.4837 showed greater differences due to the presence of alloy elements such as Cr and Ni. The comparison indicated that due to the presence of flake graphite, the HT300 hindered the corrosion of the aluminum alloy melt on the substrate, which has the best corrosion resistance. Furthermore, the corrosion mechanism of the aluminum alloy melt on different stirring paddles were also analyzed. During the stirring process, the liquid aluminum and iron-based stirring paddle infiltrated, dissolved, and adsorbed each other. Due to the reaction and diffusion of the aluminum and iron atoms, the Fe–Al intermetallic compound layer was gradually formed at the interface of the iron-based material and aluminum melt, and the presence of Si, Cr and other elements leaded to the formation of more complex intermetallic compounds.