TAN Wen
,
LIU Zhenyu
,
WU Di
,
WANG Guodong
钢铁研究学报(英文版)
An artificial neural network (ANN) model for predicting transformed microstructure in conventional rolling process and thermomechanical controlled process (TMCP) is proposed. The model uses austenite grain size and retained strain, which can be calculated by using microstructure evolution models, together with a measured cooling rate and chemical compositions as inputs and the ferrite grain size and ferrite fraction as outputs. The predicted results show that the model can predict the transformed microstructure which is in good agreement with the measured one, and it is better than the empirical equations. Also, the effect of the alloying elements on transformed products has been analyzed by using the model. The tendency is the same as that in the reported articles. The model can be used further for the optimization of processing parameters, microstructure and properties in TMCP.
关键词:
artificial neural network;TMCP;microstructure;ferrite grain size
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
WANG Shuhan
,
LIU Zhenyu
,
WANG Guodong
,
et al
钢铁研究学报(英文版)
In the present paper, tensile tests of Fe-30Mn-5Si -2Al steel were carried out for different strains of 0.05, 0.14, 0.26, and up to the strain-to-failure in order to observe the evolution of microstructure during deformation and investigate the strain hardening behavior. Three-stage strain hardening behavior was observed in this steel during tensile test. In stage I, planar dislocation structure was observed by TEM to be the main deformation mechanism, and low strain hardening rate exponent was exhibited. Primary deformation twinning occurred in stage II, and the strain hardening rate exponent increased due to the blockage of dislocations’ motion by twin boundaries. In stage III, the strain hardening rate exponent had increased to be higher than 0.5. The obstacle effect of twin boundaries and twin-twin interaction had been observed by TEM, and the interactions between primary and secondary twins were found to cause the additional hardening in addition to the obstacle effect on dislocations’ motion, which led to the twinning induced plasticity effect in the later stage of deformation.
关键词:
TWIP steel;strain hardening;Twins;dislocations
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
王浩
,
刘国权
,
秦湘阁
金属学报
采用Potts模型Monte Carlo方法对3种现存的三维个体晶粒长大速率拓扑依赖性
方程进行了仿真验证. 结果表明, Rivier速率方程认为晶粒
体积变化率dVf/dt与晶粒面数f成线性关系, 与仿真
结果明显不符, 不适用于描述三维晶粒长大过程的动力
学. 当晶粒面数f≥8时, Yu-Liu速率方程和
MacPherson-Srolovitz速率方程均与仿真结果很好吻合,
表明这两者均可以用来定量描述三维晶粒长大过程的动力学；当
f＜8时, 这两个方程均与仿真结果有显著差异.
关键词:
三维晶粒长大
,
topology-dependent grain growth rate equation
王浩
,
刘国权
,
秦湘阁
金属学报
doi:10.3321/j.issn:0412-1961.2008.01.003
采用Potts模型Monte Carlo方法对3种现存的三维个体晶粒长大速率拓扑依赖性方程进行了仿真验证.结果表明,Rivier速率方程认为晶粒体积变化率dVf/dt与晶粒面数,成线性关系,与仿真结果明显不符,不适用于描述三维晶粒长大过程的动力学.当晶粒面数f≥8时,Yu-Liu速率方程和MacPherson-Srolovitz速率方程均与仿真结果很好吻合,表明这两者均可以用来定量描述三维晶粒长大过程的动力学;当f<8时,这两个方程均与仿真结果有显著差异.
关键词:
三维晶粒长大,拓扑依赖性长大速率方程,Potts模型,Monte Carlo仿真
王浩
,
刘国权
金属学报
doi:10.3321/j.issn:0412-1961.2008.07.001
以MacPherson-Srolovitz提出的三维个体晶粒长大拓扑依赖速率方程以及三维晶粒组织的晶粒尺寸-晶粒面数间的抛物线型统计关系为基础,导出了相应的描述三维准稳态晶粒尺寸分布的函数族.采用纯Fe实验数据以及顶点法、基元演化法.相场模型和Monte Carlo法进行了验证,结果表明,函数族中峰值左偏的函数适合三维准稳态晶粒尺寸分布的定量表述.将该函数与Liu等提出的2种三维准稳态晶粒尺寸分布函数进行的对比表明:此3种函数的解析表达形式有所不同,但其曲线图在一定条件下相互吻合.此外,MacPherson-Srolovitz三维拓扑依赖速率方程、Hillert三维速率方程及Yu-Liu三维速率方程尽管表达形式不同均能较好地反映三维正常晶粒长大的动力学规律.
关键词:
三维晶粒长大
,
准稳态晶粒尺寸分布
,
长大速率方程
,
计算机仿真
