molding
(CIM) was also characterized. The result shows that
the WAIM part exhibits a distinct skin-core-water channel
structure which is different from the skin-core structure
for the CIM part. In the skin layer of both WAIM and
CIM parts, the shish-kebab structure was formed due to
the shear stress brought by melt filling, but the lamellar
orientation parameter of CIM part is smaller than that of
WAIM part. The spherulites with random lamellar orientation
are dominant at the core of both parts owing to the
low cooling rate and feeble shear stress therein. Interestingly,
the shish structure and the lamellae with low level
of orientation can be found at the water channel layer of
WAIM part. They are attributed to the shear stress
brought by water penetration. Moreover, the lamellar orientation
parameter in water channel layer is smaller than
that of skin layer. In addition, the long period of WAIM
part first increases and then decreases with the elevating
distance from the skin surface, while that of CIM part
tends to increase monotonously. In a word, one can conclude
that the rapid cooling rate and shear brought by the
injected water have significant influence on the structural
evolution for the WAIM part.
