## On Superimposed Structure in Dendrite Structure

Akira Suzuki1 and Takeshi Suzuki1

1Central Research Laboratory, Kobe Steel, Ltd., Kobe

#### Abstract:

Superimposed structure'' is often observed in the macrostructures of castings in addition to primary and secondary dendrite arms.
On the basis of the platelike morphology of dendrite, a possible mechanism has been proposed by which superimposed structure appears.
The mechanism predicts the following relationship,

tan α = \frac{tan δ}{tan β}
where α is the angle between a superimposed structure and a main axis of dendrite, and δ and β the angles between primary and secodary dendrite arms and a polished surface, respectively.
Examinations of this relationship for several kinds of commpercial alloy castings strongly support the mechanism and it is concluded that the superimposed structure is not a structural constituent but a section on the polished surface of a plate which is formed by dendrite arms.