The Research On The Influence Of Electromagnetic Field On The Al-Si And Tin Phosphorus Bronze Alloys

With the development of electromagnetic technique, electromagnetic field plays an important role in the control of metal solidification, the betterment of structure and performance. Since now, many kinds of electromangnetic methods have beed used to material peocessing. Despite of these improvments, there are still many misuderstands in the mechanics of solidification under electromagnetic field. Aiming at the solutions of the problems in the casting of Al-Si alloy and tin phosphorus bronze, this paper applied two kinds of fields, direct current field and alternating electromangnetic field, to better the solidification structures of the two alloys and analyzed the effect of these two fields to the solidification structures. Through amounts of experiments to the adjustments of experiment technics and the optimization of technic parameters, we successfully obtained two kinds of fine structures of the two alloys above.Eutectic structure was refined in the direct electric field and the refined degree first increased and then decreased with the enhancement of density. Imposing single direct current magnetic field contributed little to the refinement of eutectic structure, however, enhanced the aggregation of primary phase Si to the edge of the sample. Under perpendicular direct current and static magnetic, the refinement of eutectic structure was more effective and reticular shape eutectic cluster structure was formed. The mechanism of the above results was also discussed.In horizon continuous casting of tin phosphorus bronze QSn6.5-0.1 band, the imposing of electromagnetic field can improve the quality of the casting blank. Without electromagnetic field, the crystal grain was coarse and columnar crystal was the most;with electromagnetic field, the grain was refined and equiax crystal was the most. The segregation of Sn obviously decreased with the application of electromagnetic field and the microstructure was more uniform. Imposing 18 A electric current to the casting blank, the tensile strength decreased and extensibility increased, which facilitated to the plastic working and reducement of surface cracks. It is hopeful to decrease casting temperature at 20-30℃ and prolong the operating life of the graphite jig from 7 days to 14 days with the application of electromagnetic field.