| The effects of magnesium diffusion on the spheroidization of flake graphite with Fe-C and Fe-C-Si alloys have been investigated by means of microscopy. In this study, solid cast iron was immerged in molten magnesium bath to diffuse magnesium into the cast iron. The spheroidization of the flake graphite was accomplished by the magnesium diffusion. The results obtained from this experimental work are summarized as follows: 1) The flake graphite near the surface of the cast iron was changed to the fine nodular or lump shape by the magnesium diffusion. 2) The thickness of diffusion layer formed by the magnesium diffusion, which is dependent on the diffusion temperature, time and carbon equivalent, was about 0.2 ㎜ to 0.4 ㎜. 3) Graphite content was decreased in the surface layer where magnesium diffused and the decreased graphite was accumulated under the diffusion layer. 4) In the Fe-C-Si alloy, the shape of graphite formed on the surface became more spherical with the increase in silicon content. 5) With the X-ray diffraction patterns, it was considered that certain intermetallic compound was formed in the diffusion layer. |
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