Effect of Niobium on Dynamic Recrystallization Behavior of 5% Ni Steel

The single-pass hot compressions of two 5% Ni steels with and without niobium addition at different temperatures of 800—1150 C and strain rates of 0. 01—1 s−1 were performed by using a Gleeble-3500 thermal simulator and the effect of niobium on the dynamic recrystallization (DRX) behavior was analyzed. The results showed that the niobium addition of 0. 04% can retard DRX in 5% Ni steel significantly by increasing the activation energy for DRX from 394 to 462 kJ/mol. The critical strain required for starting DRX in 5% Ni steel was increased by 0. 04—0. 10 with niobium addition when the steel was deformed at a strain rate of 0. 01 s−1 and temperatures varied from 950 to 1000 °C. The critical temperature required for starting DRX in 5% Ni steel was also increased from 1000 to 1050 °C with niobium addition when the steel was deformed at a strain rate of 0. 1 s−1. Such a retarded DRX occurring in Nb-added 5% Ni steel can be attributed to the pinning effect of precipitates containing niobium.