2016年, 第23卷, 第11期　刊出日期：2016-11-15

  

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Review
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  Periodic Layered Structure Formed during Interfacial Reaction

  Xian-man ZHANG,Hong-feng LUO,Liu-yong SHI

  中国钢铁期刊网. 2016, 23(11): 1127-1133.

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  A review of the periodic layered structure (PLS) formed during reactive diffusion was presented. The formation of PLS is a very interesting and complex phenomenon during the reactive diffusion process. It was firstly discovered occasionally. The formation of PLS has been reported in various solid state diffusion couples such as Zn/Ni3Si, Mg/SiO2, Zn/CuxTiy and so on, and some controversial theoretical models and formation mechanism of PLS were put forward. However, there have been few reports about the PLS formed during hot dip. The development of PLS was reviewed, and the recent progress referring to the formation of PLS during the hot dip aluminizing of a novel Fe-Cr-B cast steel was especially introduced. However, not all of the borides could form PLS in their interfacial reaction with molten Al. PLS only formed at the Cr-rich Fe2B/Al interface, while Mo-rich Fe2B fractured. A general qualitative description for the interfacial reaction of Fe-Cr-B cast steel with molten Al was represented. Further investigation on the constituents of the alternating phases and formation mechanism of PLS needs to be done. At last, the development trends of PLS were proposed.
Metallurgy and Metal Working
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  Effects of Magnetic Pressure Constraint on Dynamic Deformation and Oscillation Behavior of Metal Free Surface

  Yang LI,,An-yuan DENG,,Chuan-qi YIN,,Sai-juan ZHANG,,En-gang WANG,

  中国钢铁期刊网. 2016, 23(11): 1134-1141.

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  A new method was presented to constrain deformation and oscillations of liquid metal free surface by using a high frequency magnetic field. A magnetic field generator was designed to investigate its feasibility using numerical simulation and physical simulation. The results indicate the feasibility of controlling bulge deformation of liquid metal surface using magnetic pressure. Sunken deformation with a slight fluctuation occurs on the surface when magnetic pressure acts on the static liquid metal surface. The largest amplitude remains within ±08 mm even if current reaches 1400 A. In case of the bump-type deformation, the magnetic pressure strengthens gravity field by the superposition effect, dissipates the kinetic energy of metal flow impacting on free surface in advance, reduces the velocity of free surface, and decreases the bulge height. On the region without magnetic field, the liquid metal surface rises and tends to be flat because of the significant damping effect on surface fluctuation. The constraint strength of the magnetic pressure increases with the augment of current intensity. However, different heights of bulge deformation should have a corresponding reasonable coil current for achieving the best constraint effect.
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  Numerical Analysis of Complicated Heat and Mass Transfer inside a Wustite Pellet during Reducing to Sponge Iron by H2 and CO Gaseous Mixture

  Zare Ghadi ARIYAN,Valipour MOHAMMAD SADEGH,Biglari MOJTABA

  中国钢铁期刊网. 2016, 23(11): 1142-1150.

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  Heat and mass transfer through a wustite pellet during converting to sponge iron was investigated. Pellet was reduced by a gaseous mixture containing CO and H2. The grain model was considered to simulate gas-solid reaction rate. A finite volume method (FVM) was implemented for solving the governing equations. The heat transfer mechanism around the pellet includes radiation and convection and within the pellet, effective heat transfer is considered as a blend of particles conduction and intraparticle radiation. Heat and mass distribution along the radius of pellet for two cases of reducing gases composed of pure H2 and pure CO was investigated. Local fractional reduction through the pellet was plotted to examine the heat and mass transfer behavior within the pellet and find their relevance with reduction degree. Afterwards, the impacts of pertinent parameters including gas ratio, pellet size and porosity were studied.
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  Multivariable Dynamic Modeling for Molten Iron Quality Using Incremental Random Vector Functional-link Networks

  Li ZHANG,Ping ZHOU,He-da SONG,Meng YUAN,Tian-you CHAI

  中国钢铁期刊网. 2016, 23(11): 1151-1159.

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  Molten iron temperature as well as Si, P, and S contents is the most essential molten iron quality (MIQ) indices in the blast furnace (BF) ironmaking, which requires strict monitoring during the whole ironmaking production. However, these MIQ parameters are difficult to be directly measured online, and large-time delay exists in offline analysis through laboratory sampling. Focusing on the practical challenge, a data-driven modeling method was presented for the prediction of MIQ using the improved multivariable incremental random vector functional-link networks (M-I-RVFLNs). Compared with the conventional random vector functional-link networks (RVFLNs) and the online sequential RVFLNs, the M-I-RVFLNs have solved the problem of deciding the optimal number of hidden nodes and overcome the overfitting problems. Moreover, the proposed M-I-RVFLNs model has exhibited the potential for multivariable prediction of the MIQ and improved the terminal condition for the multiple-input multiple-output (MIMO) dynamic system, which is suitable for the BF ironmaking process in practice. Ultimately, industrial experiments and contrastive researches have been conducted on the BF No2 in Liuzhou Iron and Steel Group Co. Ltd. of China using the proposed method, and the results demonstrate that the established model produces better estimating accuracy than other MIQ modeling methods.
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  Oxidation Kinetics, Structural Changes and Element Migration during Oxidation Process of Vanadium-titanium Magnetite Ore

  Feng PAN,Qing-shan ZHU,Zhan DU,,Hao-yan SUN

  中国钢铁期刊网. 2016, 23(11): 1160-1167.

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  The oxidation kinetics, structural changes, and elements migration during the oxidation process of the vanadium-titanium magnetite (VTM) ore were analyzed. Kinetics analysis indicated that the oxidation process was controlled by diffusion control and could be divided into interface diffusion and lattice diffusion with apparent activation energy of 9969 kJ/mol and 14408 kJ/mol in the range of 800-1000 ℃, respectively. The surface structure changed with the oxidization temperature as follows: dense surface→nano-sized sheets→submicron particles→molten particles. The compact structure changed into porous one because of the elements migration and enrichment. Both Fe and Ti elements migrated in the opposite direction during the oxidation process. The V element in the raw ore stably existed in the form of V5+ state, some vanadium migrated and occupied the tetrahedral sites of the hematite during the oxidation process.
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  Effect of Noncontact Ultrasonic Technology on Solidification Quality of Electroslag Steel

  Xiao-fang SHI,Li-zhong CHANG,Zheng-hai ZHU,Jian-jun WANG,Li ZHOU

  中国钢铁期刊网. 2016, 23(11): 1168-1176.

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  A new electroslag furnace with ultrasonic vibration introduced through water-cooled base plate was designed and the effects of ultrasonic power on the distribution of elements, compactness and carbides in the electroslag remelting (ESR) ingots was investigated. The results showed that the distribution of elements on the entire excitation section changed with the change of ultrasonic power under experimental conditions. The statistical segregation of elements was minimum when the ultrasonic power was 500 W, whereas excessively high or excessively low power was not conducive to the uniform distribution of elements. Meanwhile, the compactness of ESR ingots gradually increased with the increase in ultrasonic power and distribution of compactness was the most uniform when ultrasonic power reached 500 W. Further increase in the ultrasonic power was not conducive to the improvement of compactness. The distribution characteristic of carbides was similar to the distribution of elements and compactness. The results indicated that the ultrasonic vibration introduced through water-cooled base plate was advantageous in improving solidification quality. However, this method needed reasonable ultrasonic power. Moreover, the effects of ultrasonic power varied for different elements.
Material
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  Evaluation of Zero and Sub-zero Temperature Tensile and Impact Properties of Quenched and Tempered Steel Weldments

  M. BALAKRISHNAN,V. BALASUBRAMANIAN,MA. MUTHU MANICKAM

  中国钢铁期刊网. 2016, 23(11): 1177-1187.

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  Combat vehicles using armour grade quenched and tempered (Q&T) steel are needed to be operated under different climatic conditions. However, the properties meeting the room temperature test conditions may not necessarily be required to meet the low temperature operating conditions. The influences of shielded metal arc welding (SMAW) process, flux cored arc welding (FCAW) processes and test temperatures below room temperature up to -60 ℃ on tensile and impact toughness properties of armour grade Q&T steel welds were reported. The tensile and impact properties of the joints showed incremental trend with respect to the decrement in test temperature up to -40 ℃ irrespective of the welding processes used. The increment in tensile and impact properties of SMAW and FCAW joints subjected to the low temperature environment is due to plastic strain-induced phase transformation of retained austenite into martensite phase. Among the two processes, SMAW process welded joint showed better tensile and impact properties than its FCAW counterpart joints.
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  Relationship between Hydrogen Diffusion and Blistering Nucleation and Growth

  Jin-xu LI,Hang YIN,Xi-na YANG,Qian LI,Ping ZHANG,Chun-qian XIE,Yan-jing SU,Li-jie QIAO

  中国钢铁期刊网. 2016, 23(11): 1188-1194.

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  The formation condition of hydrogen blister in 18Ni maraging steel without any inner or external stress was investigated. The results show that the critical diffusible hydrogen concentration of a blister forming is about 14×10-5, which is corresponding to the current density of 30 mA/cm2 during cathodic charging in a sodium hydroxide solution. For a 01 cm thick sample, no matter the current density is equal to or much larger than the critical value, it spends at least about 132 h to form a hydrogen blister when hydrogen charging in single direction. It is approximately equal to the time for hydrogen atom to diffuse throughout the sample, which exactly depends on the hydrogen diffusion coefficient and the penetration depth. The very first clear suggestion was reported that the incubation period for hydrogen blister nucleation was necessary. According to the Fick′s laws, calculations show that the normalized hydrogen concentration in the escaping surface almost reaches 096 times of the charging surface, which means that the diffusion almost reaches a dynamic balance. A model was illustrated to describe the competitive relationship between hydrogen diffusion and blister formation.
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  Laser Surface Alloying of Low Carbon Steel Using High-entropy Alloy Precursors

  Xiao-tao LIU,,Wen-bin LEI,,Qun-jiao WANG,,Wei-ping TONG,,Chang-sheng LIU,Jian-zhong CUI,

  中国钢铁期刊网. 2016, 23(11): 1195-1199.

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  The Al05CoCrCuFeNi high-entropy alloy powders with simple face-centered-cubic (FCC) solid solution structure were introduced into the surface layer of a low carbon steel during laser surface alloying. A high performance surface layer with extremely fine martensite as the dominant phase was obtained, resulting in a great improvement in microhardness, wear resistance, and corrosion resistance. The great enhancement of microhardness and wear resistance of the laser alloyed layer is mainly due to the formation of extremely fine martensite hard phase, the solid solution strengthening of the alloying elements in supersaturated α-Fe solid solution, and the existence of size effect and strain effect under rapid solidification. The enhancement of corrosion resistance is due to the alloying of Al, Co, Ni, Cr and Cu in the laser alloyed layer.
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  Corrosion Behavior of Fe-based Bulk Metallic Glass and In-situ Dendrite-reinforced Metallic Glass Matrix Composites in Acid Solution

  Fan YANG,Sheng-feng GUO,Ai-dong LAN,Hui-jun YANG,He-feng ZHOU

  中国钢铁期刊网. 2016, 23(11): 1200-1205.

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  The corrosion behavior study was conducted on a novel Fe77Mo5P9C75B15 in-situ metallic glass matrix composite (MGMC). This composite sample was developed by introduction of bcc α-Fe dendrites as reinforcing phase. The corrosion behavior of this composite was compared to its monolithic counterpart and other Fe-based alloys such as 304L and 2304L stainless steels. The corrosion resistance of MGMCs in H2SO4 solution shows inferior to that of other Fe-based alloys. Experiments suggest that Fe-BMGs samples possess better corrosion resistance property than that of Fe-MGMCs. The possible underlying reasons can be the inhomogeneity induced by the precipitation of α-Fe dendrites in the MGMCs.
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  Fracture Characteristics of Fully Pearlitic Steel Wire in Tension and Torsion

  Tian-zhang ZHAO,Guang-liang ZHANG,Shi-hong ZHANG,Ling-yun ZHANG

  中国钢铁期刊网. 2016, 23(11): 1206-1212.

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  The fracture characteristics of fully pearlitic steel wires with fine and randomly oriented lamellae have been investigated after tension and torsion, respectively. It is found that the predominant fracture mode under small pre-deformation is dimple. The analysis of the colony size and the lamellar structure near the fracture surface indicates that each dimple roots from one colony. A simulation of tensile deformation with several pearlitic colonies based on the real scanning electron microscopy (SEM) observation shows that the plastic deformation concentrates and the stress traxiality is larger at the boundaries of colonies. It demonstrates the microcracks initialize at colony boundaries. Thus, the colony size is a significant factor for fracture behaviors under small pre-deformation. On the other hand, the fracture surface is investigated after large pre-deformation via torsion. The results show that fracture characteristics vary with radius from dimples, elongated dimples to the fibrous structure. It indicates that the fracture characteristics are dependent on the pre-deformation. The fracture mode under large pre-deformation becomes an anisotropic fibrous structure instead of dimples.
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  Solid Solute Regularity of La Atom in α-Fe Supercell by First-principles

  Cai-xia WANG,Jian YANG,,Sha LIU,Xiao-lei XING,Ji-bo WANG,Xue-jun REN,Qing-xiang YANG

  中国钢铁期刊网. 2016, 23(11): 1213-1218.

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  The structure stability, elastic property and electronic structure of α-Fe supercell with La atom were investigated by first-principles, in which, generalized gradient approximation (GGA) with the Perdew Burke Ernzerhof (PBE) was used as exchange-correlation functional. α-Fe supercells with La atom include α-Fe supercell with La atom in octahedral interstitial solid solute (La-OISS), that with La atom in tetrahedral interstitial solid solute (La-TISS) and that with La atom in substitutional solid solute (La-SSS). The results show that the La-SSS α-Fe supercell is more stable than La-OISS one. The resistance to volume change, reversible deformation and stiffness of La-OISS α-Fe supercell are stronger than those of La-SSS one. Moreover, the degrees of anisotropy and ionization in La-SSS α-Fe supercell are both stronger than those in La-OISS one. The bonding strength between La atom and Fe atom in La-SSS α-Fe supercell is larger than that in La-OISS one.
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  Oxidation Behavior of Fe-based Amorphous Ribbons

  Shu-lan ZHANG,He-ping LIU,Xiao-tong FU

  中国钢铁期刊网. 2016, 23(11): 1219-1225.

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  The oxidation behavior of Fe-based amorphous ribbons was tested by annealing at 380 ℃ in air for different time with heat treatment furnace and analyzed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The mechanism of oxides formation of the amorphous ribbons was discussed in detail. The results showed that the oxides were mostly B2O3, SiO2 and Fe2O3 or FeO. With the increase of annealing time and holding temperature, the fraction of the oxides on the ribbon surface increased and the size of the oxides became larger due to the generation of new oxides and the coalescence of small oxides. The oxides have different shapes, such as round, rod and needle-shaped. Experimental results also showed that the oxides nucleated at fish scale, air pocket and impurities in priority, and the growth of the oxides was controlled by the diffusion of atoms. With the increase of the distance to the ribbon surface, the oxygen concentration decreased dramatically. Due to the low binding energy of B2O3 and the large diffusion coefficient of B atom, the B element was oxidized firstly compared with other elements. Moreover, the oxidation depths of the B2O3 and SiO2 were larger than that of Fe2O3.
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  Effects of Rare Earth, Titanium, and Magnesium Additions on Microstructures and Properties of High-boron Medium-carbon Alloy

  Xiao-li SHI,Ye-hua JIANG,Rong ZHOU

  中国钢铁期刊网. 2016, 23(11): 1226-1233.

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  In order to improve the toughness and wear resistance of high-boron medium-carbon alloy (HBMCA), a novel wear-resistant HBMCA comprising granular borocarbide was obtained by titanium, magnesium, and rare earth modifications. These modifications gave rise to greatly refined as-cast eutectic borocarbide structures and a less interconnected continuous borocarbide network. Heat treatment mostly produced broken and spheriodized borocarbides that tended to exist as isolated particles in modified HBMCA. The heat treated modified HBMCA exhibited enhanced hardness than pristine and impact toughness was improved significantly to 125 J/cm2. In addition, it displayed 239 and 17 times greater wear resistance than high-speed steel (HSS) and high nickel-chromium alloy steel (Cr25) at high temperature (500 ℃), respectively. Here, the modification mechanisms involving Re2O3, TiN, and MgO/MgS heterogeneous nuclei were discussed.
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  Correlation between Primary and Secondary Recrystallization Texture Components in Low-temperature Reheated Grain-oriented Silicon Steel

  Gong-tao LIU,Zhi-qiao LIU,Ping YANG,Wei-min MAO

  中国钢铁期刊网. 2016, 23(11): 1234-1242.

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  Low-temperature slab-reheated grain-oriented silicon steel is characterized by a sharp {411}<148> primary recrystallization texture. To date, the influence of this texture on secondary recrystallization is not clear. Microtextures in primary and secondary recrystallized sheets of low-temperature reheated grain-oriented silicon steel were examined using electron backscatter diffraction. By comparing the textures and microstructures of specific primary recrystallized grains neighboring secondary grains with those of other primary grains, the influences of primary recrystallization textures and microstructures on the orientations of secondary grains were investigated. Results show that for low-temperature reheated grain-oriented silicon steel, the primary recrystallization sheet comprises {411}<148>, {111}<112>, and {001}<120> texture components. During secondary recrystallization, the {111}<112> primary recrystallized grains were easily consumed by abnormally grown Goss, deviated Goss, Brass, or {210}<001> grains; the {411}<148> primary recrystallized grains were more resistant to being swallowed; and the {001}<120> grains were the most resistant to being consumed. For a particular primary grain, the distribution of its surrounding grain boundaries determined how easily it is consumed during secondary recrystallization. Primary grains surrounded by 20°-45° grain boundaries were consumed much earlier than those having grain boundaries above 45°, which is in accordance with high-energy grain boundary theory. In addition, special Σ9 boundaries between {411}<148> and Goss grains move more slowly than Σ9 boundaries between {111}<112> and Goss grains, which is attributed to the different positions of <110> rotation axis with respect to the normals of grain boundaries.