MA Liqiang
,
LIU Zhenyu
,
JIAO Sihai
,
YUAN Xiangqian
,
WU Di
钢铁研究学报(英文版)
Using a Gleeble 3800 thermomechanical simulator, the effect of niobium and titanium on the dynamic recrystallization (DRX) behavior of low carbon steels was investigated. Isothermal single compression tests were performed in the temperature range of 850 to 1 150 ℃ at constant strain rates of 01 to 5 s-1. The experimental results showed that the addition of niobium and titanium to the low carbon steels significantly increased both the peak stress and steady state stress. The activation energy of deformation Qd was larger than the activation energy associated with the steady state stress Qss. Furthermore, the difference between Qd and Qss became significant because of the addition of niobium and titanium. DRX is effectively retarded because of solute dragging and dynamic precipitate pinning of niobium and titanium, resulting in higher values of the peak strain and steady state strain. Finally, the influence of niobium and titanium on the DRX kinetics and steady state grain size was determined.
关键词:
peak strain;activation energy;dynamic recrystallization It is known that the experimental
ZHOU Xiaoguang
,
LIU Zhenyu
,
YUAN Xiangqian
,
WU Di
,
WANG Guodong
,
LIU Xianghua
钢铁研究学报(英文版)
Considering the effect of strain and chemical composition on precipitation behavior, new models for the start and end time of Nb(C,N) precipitation in austenite under the conditions of different temperatures and strains have been investigated for Nb microalloyed steel. The value of n in the precipitation kinetic equation has been determined by using the available experimental data in literature, which indicated that n is a constant and independent of temperature. The values of the start and end time of the predicted precipitation are compared with the experimental values. Calculated results are in good agreement with the experimental results. Also, the evolution of austenite grains before ferrite transformation is simulated by taking the effect of precipitation into consideration. The measured austenite grain size is in good agreement with predicted one prior to ferrite transformation.
关键词:
straininduced precipitation;start time;precipitation;static recrystallization;grain size
