Trade name for a niobium-alloyed nodular graphite cast iron.

For the application of niobium. Only offers low solubility in the cast iron matrix and low tendency to integrate other alloy elements into its carbide. Even very low niobium contents are sufficient to diffuse niobium carbide from the melt, predominantly in compact form. The carbide neither influences the solidification of the cast iron nor the transformation processes in solid state.

For application for piston rings, the following composition is tried and tested:3.5 to 4.1 % C
2.4 to 2.9 % Si
0.2 to 0.8 % Mn
0.40 to 0.60 % Nb
0.02 to 0.07 % Mg
rest Fe.