Effect of Si Content on the Microstructure and Wear Resistance of High Chromium Cast Iron

Abstract

Effect of Si content on the wear resistance of high chromium cast iron was investigated. The result showed that the eutectic carbides were greatly refined and increased with the increase of Si addition from 0.5 to 1.5 wt.%. Meanwhile, the transformation of austenitic matrix to pearlite was observed. After destabilized treatment at 950°C for 3 h, denser secondary carbides precipitated from the matrix are observed in the alloy containing 1.5wt.%Si. Such microstructure changes leaded to the increase of hardness and improvement of abrasive wear resistance. An increase in load from 20 N to 100 N, the extent of carbide fragmentation was much greater and extended to a deeper distance. Severer fracture of carbides was observed in the alloy containing 0.5wt.%Si. The higher resistance with addition of Si was attributed to the denser secondary carbides, which strengthened the matrix between the eutectic carbides and in turn increased the mechanical support to the carbides against cracking.