This work reviews the effect of niobium on different cast irons. This alloying element has a high affinity by carbon forming carbides of the type MC; therefore, the main effect is to strengthen the matrix of the alloys due to a hard-phase dispersion mechanism. Even at low levels of niobium (<0.2%), MC carbides are found. The presence of such carbides increases hardness, yield and tensile strength in ductile irons, but the most important role is to increase wear resistance. Therefore, the use of niobium has been focussed mainly in alloyed white irons for wear resistance applications and in mottled cast iron used for rolls in hot rolling mills.
Part of the book: Progress in Metallic Alloys