In cast-in insertions of mild steel in cast iron, molten cast iron sometimes melts a part of the inserted steel, causing serious damage to the casting products. To clarify the mechanism of this phenomenon, the influence of the fluid flow of molten cast iron on the dissolved loss of inserted steel was quantitatively evaluated. The molten cast iron was poured into a self-curing mold with an inserted mild steel ring near the open bottom end. The height of the sprue was changed from 500mm to 50mm. The higher the head height, the larger was the fluid velocity. The change in the thickness of inserted steel ring was measured in relation with the pouring time. The experimental results showed that the thickness of steel linearly decreased with the increase in pouring time and flow velocity of the molten cast iron. Widmanstätten ferrite structures and a slightly large amount of pearlite appeared near the surface of the dissolved steel. Temperature measurement and analysis revealed that the dissolved loss of steel started at a temperature considerably lower than the melting point of cast iron. This indicates that the mild steel surface was softened by the heat of molten cast iron and eroded by the fluid flow.
