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
ZHAO Hongzhuang
,
Seokjae LEE
,
Youngkook LEE
,
LIU Xianghua
,
WANG Guodong
钢铁研究学报(英文版)
This study aims at the experimental analysis of the transformation induced plasticity (TRIP) phenomenon. Experiments are conducted in which martensite is allowed to grow under the influence of a series of externally applied stresses. The magnitude of the applied stresses is less than 67% of the yield strength of austenite σγ(Ts). Since there is no obvious difference between the transformation plasticity under tension and the compression for the lower applied stresses, only compressive stresses are applied. The results confirm that the transformation plasticity is proportional to the applied stress if the latter does not exceed 67% of σγ(Ts). The TRIPstrain, the kinetics, and their dependence on the applied stresses are studied. The comparison between calculated results and experimental results shows that the model accurately describes the phenomenon.
关键词:
applied stress;TRIP;martensite transformation;lowalloy steel
TIAN Yong
,
GUO Yanhui
,
WANG Zhaodong
,
WANG Guodong
钢铁研究学报(英文版)
The plane strain asymmetrical rolling was analyzed using slab method. The contact arc was replaced by parabola, and the constant surface friction status was adopted during the analysis. The deformation area was divided into three zones according to the direction of the friction. Then, the three zones were studied, respectively. A rolling force model and a rolling torque model were developed based on the analysis, and they were used to analyze the influence of asymmetrical rolling factors on deformation area and unit pressure if they had good precision which was determined by comparing the calculated results with the measured ones.
关键词:
asymmetrical rolling;slab method;asymmetrical factor;specific pressure distribution
XU Yunbo
,
YU Yongmei
,
LIU Xianghua
,
WANG Guodong
钢铁研究学报(英文版)
Based on thermodynamics and kinetics, a new mathematical model was developed to calculate the CCT diagrams and the transformation kinetics in low carbon niobium steels, in which the effect of deformation on the degree of supercooling was taken into account. The undercooling caused by deformation is the major reason for the increase of the starting transition temperature during continuous cooling. The critical cooling rate of bainite formation is within 2-5 ℃/s for the studied niobium steels and deformation is suitable for the occurrence of pearlite. The ferrite volume fraction increases with the increase of the austenite boundary area, and decreases with the increase of the cooling rate. The calculated CCT diagrams and the volume fraction of each phase are in good agreement with the measurements.
关键词:
low carbon niobium steel;thermodynamics;supercooling degree;continuous cooling transformation;computer model
WANG Bingxin
,
JIANG Yingtian
,
XU Xudong
,
LIU Xianghua
,
WANG Guodong
钢铁研究学报(英文版)
The effect of compressive deformation of austenite on continuous cooling transformation microstructures for 22CrSH gear steel has been investigated using a Gleeble 1500 thermal simulator. The experimental results show that the deformation of austenite promotes the formation of proeutectoid ferrite and pearlite, and leads to the increase of critical cooling rate of proeutectoid ferrite plus pearlite microstructure. The grain boundary allotriomorphic ferrite occupies the austenite grain surfaces when the prior deformation takes place or the cooling rate is decreased, which causes a transition from bainite to acicular ferrite. The deformation enhances the stability of transformation from austenite to acicular ferrite, which results in an increase of M/A constituent.
关键词:
gear steel;prior compressive deformation;austenite;transformation;microstructure
DU Linxiu
,
ZHANG Zhongping
,
TIAN Yuwei
,
LIU Xianghua
,
WANG Guodong
钢铁研究学报(英文版)
gy Center, Benxi Steel Group, Benxi 117000, Liaoning, China)
Abstract： The fatigue properties of 400 MPa grade supersteel, plain low carbon steel SS400 and microalloyed steel Q340TM were investigated through tensilecompression fatigue experiment with R=-1. The results indicate that the fatigue limit of the 400 MPa supersteel is higher than that of SS400 steel and close to that of the 340TM steel. According to the analysis of fatigue fracture, the fatigue striations of supersteel SS400 is thinner than that of SS400 steel and 340TM steel, and grain refinement can increase the fatigue limit.
关键词:
supersteel;grain refinement;fatigue property
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
YU Hailiang
,
LIU Xianghua
,
LI Changsheng
,
WANG Guodong
钢铁研究学报(英文版)
The deformation of slab with dogbone shape during the horizontal rolling process was simulated using FEM, and the influences of apical dislocation of dogbone on the slab spread as well as the minimum crop end loss and the lost width at slab head and tail were analyzed. The results show that with the increase in the apical dislocation of dogbone (LA), the slab spread and the minimum crop end loss at slab head and tail decrease, while the lost width at slab head and tail increases. Meanwhile, the relationships of S/LALA, LH/LALA, WH/LALA, LT/LALA, and WT/LALA were obtained.
关键词:
dogbone;apical dislocation;horizontal rolling;FEM
GUO Yanhui
,
WANG Zhaodong
,
ZOU Wenwen
,
LIU Xianghua
,
WANG Guodong
钢铁研究学报(英文版)
The texture evolution in a high strength TiIF steel during the processing of hot rolling, cold rolling, and annealing is studied. For comparison, both ferrite rolling and austenite rolling are employed. It is found that the texture type is the same after ferrite rolling and austenite rolling, but the texture intensity is much higher in the ferrite rolled sample. Furthermore, texture characteristics at the surface are absolutely different from those at the midsection in both ferrite rolled and austenite rolled samples, as well as under the cold rolled and annealed conditions. The shear texture {110}<001> disappears and orientation rotates along {110}<001>→{554}<225>→{111}<112>→{111}<110>→{223}<110> during cold rolling. Compared to the austenite rolled sample, the properties of the cold rolled and annealed sheet which is subjected to ferrite rolling are higher.
关键词:
high strength TiIF steel;ferrite rolling;austenite rolling;texture
LI Haijun
,
XU Jianzhong
,
WANG Guodong
,
LIU Xianghua
钢铁研究学报(英文版)
Load distribution is a key technology in strip hot rolling process, which influences the coil′s microstructure and performance. Currently, NewtonRaphson algorithm is applied to load distribution of hot tandem mills in many hot rolling plants and has some serious defects such as having a strict restriction on initial iterative calculation value and requiring coefficient matrix of nonlinear equations to be nonsingular. To eliminate these defects and improve the online performance of the process control computer, Newton descendent numeric algorithm is introduced to this field to widen the initial value range and a new model named error conversion algorithm is put forth to deal with special conditions when the coefficient matrix is singular. Furthermore, considering the characteristics of load distribution, a condition of strip thickness distribution abnormality and corresponding solutions are provided which ensure that rolling parameters can be calculated normally. Simulation results show that the improved algorithm has overcome the defects of the NewtonRaphson algorithm and is suitable for online application.
关键词:
load distribution;hot tandem mill;process control computer;NewtonRaphson algorithm
