The figure shows the relationship between the hardness of white cast iron and the wall thickness of the sample. It can be seen from the figure that the Rockwell hardness value of white cast iron gradually increases with the increase of sample wall thickness. The hardness of white cast iron is mainly related to the content of carbides in the alloy. When the metal melt is undercooled below the eutectic line, the transformation from eutectic melt to cementite and austenite will occur in white cast iron, and eutectic solidification will occur.
At this time, eutectic (carbide (or cementite) and austenite) nucleate and grow. The carbide in eutectic is the main hard brittle phase, which has an important effect on the properties of white cast iron. When the carbide content is high, the hardness of the alloy is high, otherwise, the hardness value is low.
The analysis shows that the content of ledeburite in the alloy increases with the increase of sample wall thickness, which is the main reason for the increase of Rockwell hardness of white cast iron with the increase of sample wall thickness.