Solidified Structure of S45C Steel With and Without the Imposition of Electromagnetic Field
Kazuhiko Iwai, Takenori Kohama
S45C carbon steel has been solidified under the simultaneous imposition of a static magnetic field in vertical direction and an alternating current having a horizontal component. Thus, an electromagnetic force was excited in the S45C steel sample and it affected structure formation during the solidification. The samples solidified under different electromagnetic conditions were cut and chemically etched for observation of the macro- and micro-structures. Solidified structure in the case neither the static magnetic field nor the alternating current was not imposed was dendritic structure. On the other hand, solidified structure under the simultaneous imposition of the 1 T static magnetic field and the alternating current of 80 A, 2 kHz was equi-axed structure. When the magnetic field intensity was decreased from 1 to 0.3 T, equi-axed structure and dendritic structure co-existed. As the frequency of the 80 A alternating current decreased from 2 kHz to 100 Hz under the constant magnetic field intensity of 1 T, solidified structure changed from equi-axed structure to dendritic one. Mechanism of the structure change is supposed to be breaking dendrites into pieces by convection induced in the sample by the non-uniform distribution of the electromagnetic force, which was intensified as the frequency of the alternating current increased.
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