Segregation position of impurity elements in large wheel hub in reverse squeeze casting

According to the data in Table 1, the segregation position of each element along the longitudinal direction can be further calculated. Except for Mn and Zr which are basically non segregated, the maximum deviation between the content of each impurity element and the average content is shown in Table 2. Except for Ca, the position with the lowest content of each element is the last filling position No.8. This shows that the content of impurity elements is not high at the last filling position in reverse squeeze casting, which is different from the common conjecture. The highest content of each impurity element is in position 5, 6 and 7. These three positions are the flow channel of reverse squeeze casting. Therefore, this kind of segregation can also be regarded as channel segregation.

Similarly, according to table 1, the radial segregation position of each impurity element can be obtained, as shown in Table 3. It can be seen that except for P, the contents of other impurity elements are the lowest at position 2 about 1 / 2 of the indenter radius below the indenter, while the contents are higher at position 1 in the center and position 5 at the edge. The connection between position 2 and position 5 forms the channel of horizontal flow in squeeze casting, which indicates that there is channel segregation in the radial direction of reverse squeeze casting. Position 1 also belongs to the segregation position, which is located in the center under the punch (indenter) and in the “deformation dead zone”. It is better to call this position “zero flow” position, and call this kind of segregation “zero flow segregation”. No. 4 is located at the outer rim. Due to the structure of the workpiece, the metal melt has almost no rheology in the process of reverse extrusion filling and feeding, which also belongs to the “zero rheology” position. However, the wall thickness is small, which is the first solidification position. The impurity element content is relatively low, which also belongs to the segregation position (but not the most serious segregation position).

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