Research On Interaction Between Rare Earth Cerium And Low Melting Point Metallic Tin In Steel

With a view to protect the environment against pollution and save the resource, it will play a special role in steelmaking using scrap steel as the main raw material. It is inevitable that the contents of low melting point metallic elements in the recycled steel might become highter than the original steel. It is hard to remove the elements of Sn, Pb and Sb in the conventional process of steelmaking. These tramp elements tend to make the steel products deterioration, sensitive to the surface cracking and temper brittleness. Rare earthes are often used to purify steel and easily react with oxygen, sulfur and phosphorus.The Ce-Sn intermetallics can be formed according to the binary phase diagram of Ce-Sn. The reaction between the rare earth metallic cerium and the low melting metallic tin in steel have been studied under the different conditions by means of metallography, electron microprobe and microhardness tester in this paper.The CeSn₃ phase, which appears grayish both in light field and in backscattered electron image, could be formed in infiltrating sample after heated at 1213K for 116h, but unstable in the air, can reacts with water vapor to produce Ce(OH)₃ and tin. The Ce₃Sn₇ phase contained a little of Fe could be formed in the cast sample under the high contents of cerium and tin, distributed along grain boundaries in the cast sample and appeared grayish in light field, the ability of light reflex is lower than the matrix. During the austenitizing treatment process of heated at 1213K for 52h, FeCe₃Sn₆ phase which appears grayish near the color of matrix in the light field can be formed from the Ce₃Sn₇ phase in the cast sample, whose microhardness is 270±10HV0.05 in annealed sample much harder than the matrix, stable both in the exsiccator and in the alkaline solution, but unstable even in the purified water, whose speed of corrosion is slower than that on matrix in acid solution.