Microstructure Refinement in Non-Quenched and Tempered Vanadium-Nitrogen Steel
In order to study the effect of second phase precipitation on the refinement of microstructures during static recrystallization, the former researched non-quenched and tempered vanadium-nitrogen steel was chosen to conduct single and double-pass compression experiment by hot deformation simulator and the fraction of static recrystallization at different isothermal times was calculated. The precipitates were analyzed by TEM with accessories of EDS and energy filter. The results showed that precipitates in austenite during the pass isothermal times were mainly the (Ti, V) (C, N) with size varying from 55 to 140 nm, and during cooling and phase transformation were mainly vermicular VC with length in the range of 22-100nm and width 13-39nm. The key factor for refining the final structures: during short isothermal times is static recrystallization; during static recrystallization stagnation plateau is intragranular ferrites nucleated on precipitation phases; after stagnation plateau is intragranular ferrites promoted by the local solute-poor regions.
Pengcheng Wang, Liqun Ai, Yungang Li, Xiaoming Sang and Jinglong Bu
H. B. Li et al., "Microstructure Refinement in Non-Quenched and Tempered Vanadium-Nitrogen Steel", Advanced Materials Research, Vols. 295-297, pp. 991-996, 2011