Effect of C and N on static recrystallization in vanadium microalloyed non-quenched/tempered steels

The Gleehle-1500 thermal/mechanical simulator was used to study static recrystallization in four non-quenched/tempered steels with V-N-microalloying and one non-microalloying base steel. The results show that in the V-N microalloved steel with 0.33% C, the static recrystallization process was retarded markedly in comparison with that in the non-mlcro,alloying steel with the same C content, especially in the range of 820 to 880℃. However, the relationship between C content and static recrystallization was not linear for the microalloyed steels studied. Compared that for the steels with lower or higher C contents, the inter-pass static recrystallization amounts in the 0.33% C steel were always the maximum within the temperature range of 760 to 880℃, though all the five tested steels completed static recrystalllzation under 940℃. Such results indicated that the effect of V-contalning precipitates on the inter-pass static recrystallization process was fairly complex and depended on when the precipitation occurs. When the mass fraction of N increased from 140×10^-6 to 210×10^-6 and the other compositions were almost the same, the inter-pass static recrystallization amount decreased by 14% to 19% in the temperature range of 820 to 860℃;, showing that the increase of N content would restrain static recrystallization obviously.