Number：

01099021

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Name：

Dong Shyen Yang

Titles：

Lecturer

Author：

Dong Shyen Yang , Tien Shou Lei

Paper name：

The effect ofmicrostructure on unidirectional chilled solidification of high chromium white cast iron

Name of activity：

Advanced Materials Rearch

Keywords：Furan sand model, directional solidification, temperature gradient, carbide

Abstract：

This study mainly investigates the characteristics of carbide and the matrix structure of ASTM A532-87 CLASS III high-chromium white cast iron under directional solidification. The two components of high-chromium white cast iron were put in a 3-level Furan sand model, which is placed in a cold-water circulation copper model, producing unidirectional chilled solidification. AK-type thermocouple is employed to measure data for solidification temperature with time. The move velocities of the liquidus phase and solidus phase is calculated. The matrix and the growth characteristics of M₇C₃ carbide are explored. As determined from the experiment, the liquidus temperature gradient G_L is 0.45~0.9℃/mm, and the solidus temperature gradient G_S is 4.3~6.2℃/mm. Around 300nm of the primary carbide is formed from the added elemental nickel being less than 0.3 mm from the chilled end and from the nickel-free alloy being less than 5 mm from the chilled end. As the distance from the chilled end increases, the primary carbide gradually becomes coarser, and the distance between eutectic carbide groups is increased. This study employs EPMA to analyze the changes of primary carbide, eutectic carbide and matrix components with distance from the chilled end, as well as changes in the distributions of chemical elements.

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