Effect of Inclined Rotation Angles on The Motion of Equiaxed Grains in Centrifugal Casting

Abstract

In order to understand the role of angle of rotation axis, experimental work using organic substance has been performed. One of the advantageous points of the experimental equipment is that visual point (=the video camera) can be rotating with the glass cell, in which organic material was filled. In-situ observation has been carried out at the rotation rate of 250 rpm, changing the angle of rotation axis (η) at the interval of 30°, defining 0° as being horizontal to ground.
In case of η<90°, the equiaxed grains formed in the middle of solidification process. Equiaxed grains oscillated with respect to the mold wall back and forth in accordance with rotation. Amplitude of oscillation decreased with increasing η. Equiaxed grains also travelled backward with respect to the rotation. Travelling length per revolution decreased with increasing η. Since the contribution of gravitational acceleration to the movement of solid/liquid mixture decreases with increasing η, the turbulence of the surface of liquid phase decreases with increasing η. In case of η=90°, the typical columnar dendrites grew from the mold and no equiaxed grains formed. The liquid phase is completely stabilized by centrifugal force, because the effect of acceleration due to gravity vanishes in this condition.