Figure 6 (a) The phase diagram of the High-Nb steel as a function of niobium concentration; (b) Overlapped phase diagram of the Low-Ti (red curves) and High-Nb (purple curves) steels
The phase diagrams were calculated for the Low-Nb steel (Table 4 ) separately due to a much higher concentration of carbon in steel 1 than the rest of the alloys in Table 3. The transformation and precipitation temperature of the Low-Nb steel as a function of carbon and niobium concentration are shown in Figure 7 . Similar to the High-Nb steel, the precipitation temperature of niobium carbides is increased with niobium concentration.