Solidified Structure of S45C Steel with and without the Imposition of Electromagnetic Field
Kazuhiko Iwai, Takenori Kohama
A 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 sample and it affected structure formation during the solidification. The samples solidified under the different electromagnetic conditions were cut and chemically etched for the observation of the macro- and micro-structures. And those were compared each other. Without the imposition of the static magnetic field and the alternating current on the steel, micro-structure was dendrites. On the other hand, the solidified structure under the 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 to 0.3 T, some parts of the solidified structure were equi-axed structure. As the frequency of the 80 A alternating current decreased under the constant magnetic field intensity of 1 T, the solidified structure changed from dendritic structure to equi-axed structure. Grain refinement mechanism 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 electric current increased.
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