LAUSR

Effects of Nb on the microstructure and properties of Ti-added hypereutectic high-Cr cast iron were studied. With the addition of Nb, a new phase (Nb,Ti)C was formed. The microstructure analysis revealed that the amount of primary carbides was decreased from 18.6 to 8.8% and the primary and eutectic carbides were greatly refined. The decrease in the amount of primary carbides was attributed with the shrinking of primary M7C3 phase zone in the phase diagram, while the refinement of primary carbides was attributed to the heterogeneous nucleus of (Nb,Ti)C phase for the primary M7C3 carbides. The macrohardness of the alloy increased from 60.8 to 63.5HRC, and the impact toughness increased from 3.8 to 5.2 J cm−2. Furthermore, the wear resistance was enhanced with the addition of Nb due to the formation of hard (Nb,Ti)C carbides.