Effect of Si on Microstructure and Wear Resistance of Hypereutectic High-Chromium Cast Iron.

The effect of Si on the microstructure and properties of hypereutectic high-chromium cast iron was investigated. The results show that Si is only solid-dissolved in the matrix, and the content of Si is higher in the matrix near the edge of the primary carbide. As the Si content increased from 0.5 to 2.6%, the primary carbides in hypereutectic high-chromium cast iron were significantly refined, and the refining mechanism was verified by first-principles calculations. The increase of silicon content also leads to the increase of carbide volume fraction from 52.4 to 63.9%, the decrease of austenite volume fraction from 45.8 to 2.0%, and the matrix structure gradually transforms from γ-Fe to α-Fe. After hypereutectic high-chromium cast iron was quenched at 1050 °C, a large amount of secondary carbides were precipitated in the matrix and the precipitation of secondary carbides decreased significantly with the increase of silicon content. After quenching at 1050 °C, the hardness of hypereutectic high-chromium cast iron increased significantly, but the hardness of high-silicon (1.9Si and 2.6Si) samples did not change significantly. Increasing the quenching temperature and prolonging the holding time can significantly improve the hardness of high-silicon samples. The increase of silicon content can significantly improve the wear resistance of hypereutectic high-chromium cast iron. When the silicon content exceeds 1.9%, the wear resistance decreases. [ABSTRACT FROM AUTHOR]