Abstract
The distribution and precipitation of Nb atoms at an very early stage of recovery and recrystallization in hot-deformed austenite were investigated by using an atom-probe field-ion microscope (AP-FIM) and a transmission electron microscope (TEM). The results were summarized as follows: 1) Solute Nb in austenite can delay the onset of recovery and recrystallization. 2) Solute Nb has the strongest retarding effect for recovery and recrystallization among the micro alloying elements; i.e., Nb, Ti, V, Mo. This seems to be caused by the strong interaction between Nb atom and vacancy or dislocation. 3) Nb-N substitutional-interstitial atom pairs were also detected in hot-deformed austenite. This may play an important role in the retarding effect of the early stage of recovery and recrystallization by strongly interacting with dislocations.
