Erosion Resistance of Cast Steel and Spheroidal Graphite Cast Iron with a High-Manganese Content in Molten Aluminum Alloys

Erosion testing was conducted on cast steel and spheroidal graphite cast iron specimens containing large amounts of manganese and several other ferrous materials in molten aluminum alloys. Based on the results, the erosion resistance of ferrous materials with a high-Mn content was quantified, and the resistance mechanism was investigated. The erosion ratios of high-Mn-containing ferrous specimens were lower than those of specimens that did not contain a high amount of Mn. An analysis of the chemical compositions in the vicinity of the contact interfaces of the high-Mn-containing specimens after testing revealed that the manganese-to-iron content ratios in the intermetallic layers were largely the same as those in the specimens and that the ratios in the melts (solidified) were greater than those in the specimens and intermetallic layers. This small-scale enrichment of manganese could be attributed to its lower diffusion rate compared to iron. In addition, the calculated isothermal phase diagrams corresponding to the testing temperature showed that the apparent saturation solubility of iron in the molten aluminum alloys decreased with the manganese content, irrespective of the silicon content in the melts. These results suggest that the local decrease in the saturation solubility of iron in the melts owing to the small-scale enrichment of manganese in the vicinity of the solid-liquid interface can improve the erosion resistance of specimens containing a high amount of manganese.