YANG Shu-Feng LI Jing-feng
,
ZHANG Li-feng
,
et al
钢铁研究学报(英文版)
The transformation of MgO•Al2O3 based inclusions in alloy steel during refining has been studied by industrial trials. Besides Factsage software is applied to study the formation and modification of spinel inclusions in alloy steel using calcium treatment during refining process. The results show the transformation sequence of inclusions is: MgO•Al2O3 → CaO–Al2O3–MgO complex inclusions → MgO•Al2O3; In order to avoid forming MgOAl2O3 inclusions, the content of dissolved Ca in the molten steel has to reach 1ppm.
关键词:
Alloy steel;Non-metallic inclusions;MgO•Al2O3 spinel;Thermodynamics
YU Xiong
,
WEN Guang-hua
,
et al
钢铁研究学报(英文版)
Due to its high content in the Al-TRIP steel, [Al] reacts with (SiO2) in the mold slag during the casting process, which results in the increase of w(Al2O3)/w(SiO2) ratio and the Al2O3 content, respectively, the characteristic of heat transfer through the slag film is then changed, which effects the smooth operation of the continuous casting process. In this paper, the mold slag simulator was used to study the change tendency of the heat flux density through slag film and the results were discussed, at the same time, the crystals in the 15# slag were characterized by BSE and XRD. The results obtained show that:(i) Heat flux density decreases with the increase of w(Al2O3)/w(SiO2) ratio; (ii) Heat flux density increases with the increase of Li2O and/or B2O3 content in the mold slag which contain 30% Al2O3; (iii) Compared with the heat flux density of common slag of peritectic steel, an appropriated mold slag contain 4% B2O3 and 4% Li2O is designed. The heat flux density is 0.645MW•m-2 when w(Al2O3)/w(SiO2)=1.46. (iv) In the equilibrium state, mold slag used for Al-TRIP steel precipitates CaF2 crystals.
关键词:
TRIP steel;heat flux density;w(Al2O3)/w(SiO2) ratio;Li2O;B2O3
WANG Hongming
,
LI Guirong
,
LI Bo
,
et al
钢铁研究学报(英文版)
B2O3 is selected as fluxing agent of CaO-based ladle refining slag to decrease the melting temperature as well as to improve the speed of slag forming and the refining efficiency. The effects of B2O3 on the melting temperature of two series of refining slags including the low basicity slags (the mass ratio of CaO/SiO2 is 3~4) and the high basicity slags (the mass ratio of CaO/SiO2 is 5~8.75) were investigated. The slag melting temperature was measured using the hemisphere method. The results indicate that the fluxing action of B2O3 is better than that of CaF2 and Al2O3. For the CaO-based refining slag with low basicity, the melting temperature is decreased effectively when B2O3 is used to substitute for equal mass of CaF2, Al2O3 and SiO2, respectively. For the CaO-based refining slag with high basicity, when CaF2 is substituted with B2O3, the melting temperature can be decreased remarkably. Especially, when the mass ratios of CaO/Al2O3 and CaO/SiO2 are in range of 1.1~4.0 and 5.25~8.0, respectively, the slag melting temperature is lower than 1300℃. Therefore, the B2O3-containing refining slags with high ratios of CaO/Al2O3 and CaO/SiO2 have ultralow melting temperature. As a result, not only the slag forming speed but also the capabilities of desulfurizing, dephosphorizing and absorbing deoxidation products are expected to be improved.
关键词:
Fluoride-free slag;Boron oxide;CaO-based refining slag;Melting temperature;Basicity
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
LIU Xiao
,
YANG Jichun
,
YANG Lin
,
et al
钢铁研究学报(英文版)
The effect of Ce on inclusions and impact toughness of 2Cr13 stainless steel were studied by SEM and electron spectroscopy. Thermodynamic calculation was used to analyze the formation of RE inclusions in 2Cr13 stainless steel. The result shows that Al2O3 and MnS can be entirely replaced by Ce2O2S and CeS. Fracture is changed from cleavage to ductile fracture by adding Ce to the 2Cr13 stainless steel, and the spherical rare earth oxysulfide inclusions-Ce2O2S in the dimple are the main factors. The transverse impact value of 2Cr13 stainless steel has been improved obviously by rare earth. The transverse impact value of RE-2Cr13 is increased 55.46% at the temperature of -40℃, comparing with 0RE-2Cr13.
关键词:
rare earth;2Cr13 stainless steel;inclusion;thermodynamic calculation;
FU Li-Jun
,
DONG Xiang-huai
,
et al
钢铁研究学报(英文版)
In the traditional one-step formulations using shell elements, the computations of the curvature variation and bending stiffness matrix are simplified by omitting the rotational DOFs on the basis of initial flat blank and fully known final configuration. They are highly efficient but not suitable either for the forming processes with non-flat initial configurations, or for one-step forward and multi-step analyses. Thus a one-step formulation based on the rotation-free BST (Basic Shell Triangular) element is presented here. In this formulation, the following improvements are made: 1) the curvature variation can be calculated exactly and efficiently resorting to a patch of four elements without rotational DOFs, which makes the formulation suitable for non-flat initial configurations, one-step and multi-step forward or inverse analyses, 2) The penalty method, instead of traditional sliding constraint, is employed to treat contacts in the forming processes, which makes it possible to inspect some deformation defects such as wrinkling et al directly. To verify the improved formulation, a program has been developed, and the bending process of a rectangular tube is simulated, with particular attentions paid on cross-sectional distortion. The numerical results of the one-step simulation agree with those of incremental analysis and experimental values.
关键词:
One-step formulation;the BST element;the penalty method
LI Changsheng
,
YANG Hua
,
WANG Yanfang
,
et al
钢铁研究学报(英文版)
Fe-3%Si steel strip was experimental produced by thin slab casting and rolling (TSCR) process in the laboratory. The microstructure and texture of hot rolled strip by different total reduction and rolling schedule was observed through EBSD technique and X-ray diffraction method. The changeable rule of texture density on the α、ε and γ, and fibers was analyzed. When the total reduction was increased from 82.9% to 97.1%，the gradient of microstructure and texture for A steel surface layer and center layer was found, {001}‹110› texture had higher intensity, and {001}‹110› texture was changed to{110}‹001›和{112}‹111›. The texture distribution with different reduction schedule for B steel was basically similar, but the Goss texture orientation density and volume fraction for B steel were higher, the hot rolling reduction schedule of C1 was effective to the formation of Goss texture. The research works were useful theoretical basis and reference data to develop electrical steel by thin slab continuous casting and direct rolling technology.
关键词:
Silicon steel;texture;hot rolling;thin Slab;Continuous casting and direct rolling
WANG Yun-hua
,
et al
钢铁研究学报(英文版)
On the background of the bright continuous simulative annealing experimental machine, the process control model of heating system is built in the paper. The heating model was simplified and the self-learning parameter was normalized in the paper in order to enhance the precision of the temperature control. By way of dividing temperature layers and exponential smoothing disposal with the data of the annealing experiment, self-learning of heating model was carried out, and at the same time, by way of exponential smoothing with the deviation of self-learning parameter of the heated phase in heating process, dynamic modifying of self-learning parameter was carried out, and so that dynamic modifying of heating electric current was carried out, and so, the precision of temperature control was confirmed. Application indicates that the process control model of heating system can control temperature with high precision, the deviation can be controlled in 8℃,it can offer reference to the research of similar equipments, and the method of self-learning is also adapt to process control of cooling system
关键词:
annealing;simulative;experimental machine;process control;self-adaptive
YANG Jing-ming
,
ZHANG Qing
,
CHE Hai-jun
,
et al
钢铁研究学报(英文版)
Based on rolling feature of continuous tandem cold rolling mill, such as multi-variable, strong coupling, non-linear, analyze and set the equal relative load, preventing slippage and profile well as the multi-objective optimization goal, BP neural network with self-learning function is adopted to replace traditional rolling force models and then Levenberg-Marquardt algorithm is adopted to predict the rolling force. Then use multi-objective fuzzy theory to solve the problem of multi-objective optimization of tandem cold rolling schedule. With the example of 1370mm tandem cold rolling, the rolling schedule of the common rolling, the single-object optimization design and the multi-objective fuzzy optimization design are compared with each other, optimization result shows the proposed optimization method decreases the value of three objective functions simultaneous. The performance of the optimal rolling schedule is satisfying and it is promising.
关键词:
rolling schedule;tandem cold rolling;neural network;multi-objective fuzzy optimization
