Effects of carbon and niobium on microstructure and properties for Ti bearing steels

The objective of the study described here is to elucidate the effect of carbon and niobium on the microstructure, precipitation behaviour, and mechanical properties of 0·09C–0·11Ti (%) steel and 0·05C–0·025Nb–0·11Ti (%) steel under ultra fast cooling condition. The strengthening mechanisms are also discussed. The ferrite grains size and the size of precipitates in Ti and Nb–Ti steels were measured respectively. The mechanical properties obtained in Ti steel were similar to Nb–Ti steel with yield stress >700 MPa, elongation >20%, and good low temperature impact toughness. The study underscores that addition of higher carbon content by 0·04% under controlled rolling and ultra fast cooling conditions, we can achieve similar strength in the absence of micro-alloying element, niobium.