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Effects and Mechanisms of RE on Impact Toughness and Fracture Toughness of Clean Heavy Rail Steel

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Journal of Iron and Steel Research International 2011年第3期18卷 52-58页

作者： LIU Cheng-jun HUANG Ya-he jiang mao-fa School of Materials and Metallurgy Northeastern UniversityShenyang 110004LiaoningChina

Clean high carbon heavy rail steel was prepared by the process of vacuum induction furnace smelting,forging and *** of RE on the impact toughness and fracture toughness for clean high carbon steel were *** addition,the appropriate range of RE content for clean high carbon steel was *** the austenite grain size and pearlite lamellar spacing decreased due to small amount of RE,consequently the impact toughness and fracture toughness were improved *** the RE content exceeded a critical value,the pearlite lamellar spacing was increased,because RE was segregated on the austenite grain boundaries,damaged the orientation relationship of pearlite transformation,caused the disorder growth and morphology degenerating of *** the increasing of RE content,both the impact toughness and fracture toughness of clean high carbon steel were gradually increased at first and then *** was found that when the RE content was between 0.0081% and 0.0088%,both the impact toughness and fracture toughness of clean high carbon heavy rail steel were the *** maximum ballistic work was 21.2 J（20 ℃） and 12.2 J（-20 ℃）,*** maximum plane-strain fracture toughness was 45.67 MPa·m1/2（20 ℃） and 37.04 MPa·m1/2（-20 ℃）,respectively.

关键词： rare earth high carbon steel heavy rail steel clean steel impact toughness fracture toughness

Numerical Simulation for Effect of Inlet Cooling Rate on Fluid Flow and Temperature Distribution in Tundish

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Journal of Iron and Steel Research International 2012年第7期19卷 12-19页

作者： QU Tian-peng LIU Cheng-jun jiang mao-fa CISDI Chongqing Iron and Steelmaking Plant Integration Co Ltd Chongqing 401122China School of Materials and Metallurgy Northeastern UniversityShenyang 110004LiaoningChina

The fluid flow in tundish is a non-isothermal process and the temperature variation of stream from teeming ladle dominates the fluid flow and thermal distribution in tundish. A numerical model was established to investigate the effect of inlet cooling rate on fluid flow and temperature distribution in tundish based on a FTSC （Flexible Thin Slab Casting） tundish. The inlet cooling rate varies from 0. 5 to 0. 25 ~C/rain. Under the present calculation conditions, the following conclusions were made. When the stream temperature from teeming ladle drops seriously （for inlet cooling rate of 0.5℃/min）, there is a ＂backward flow＂ at the coming end of casting. The horizontal flow along the free surface turns to flow along the bottom of tundish. The bottom flow shortens the fluid flow route in tundish and deteriorates the removal effect of nonmetallic inclusions from molten steel. Nevertheless, when the inlet cooling rate decreases to 0.25℃/min, the horizontal flow is sustained during the whole casting period. The present research provides theoretical directions for temperature control in teeming ladle and continuous casting tundish during production of advanced steels.

关键词： tundish thermal distribution unsteady numerical simulation

Effects of Mineral Composition and Microstructure on Crack Resistance of Sintered Ore

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Journal of Iron and Steel Research International 2006年第4期13卷 9-12页

作者： YING Zi-wei jiang mao-fa XU Li-xian School of Materials and Metallurgy Northeastern University Shenyang 110004 Liaoning China

Vickers indentation test was used to study the effects of mineral composition and microstructure on crack resistance of sintered ore, and the initiation and propagation of cracks in different minerals contained in sintered ore were examined. The results indicate that the microstructure of calcium ferrites is a major factor influencing crack resistance of sintered ore. Finer grain size of calcium ferrite will lead to higher cracking threshold and better crack resistance of sintered ore. The formation of calcium ferrite with fine grain size during sintering process is favorable for crack resistance of sintered ore.

关键词： calcium ferrite crack fracture toughness cracking threshold

A Coupling Dynamic Model for Dissolution and Reduction of Chromium Ore in a Smelting Reduction Converter

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Journal of Iron and Steel Research International 2012年第1期19卷 5-10页

作者： LIU Yan jiang mao-fa XU Li-xian WANG De-yong Liaoning Provincial Key Laboratory of Advanced Materials and Preparation Technology Shenyang UniversityShenyang 110044LiaoningChina School of Materials and Metallurgy Northeastern UniversityShenyang 110004LiaoningChina

For describing and resolving the process of chromium ore smelting reduction in a converter preferably, the coupling dynamic model was established based on the kinetic models of chromium ore dissolution and interfacial re- ducing reaction between the slag and metal. When 150 t stainless steel crude melts with chromium of 12% are produced in a smelting reduction converter with no initial chromium in metal at 1 560℃, the results of the coupling dynamic model show that the mean reduction rate and injection rate of chromium ore are 0. 091% ·min^-1 and 467 kg · min^-1 , respectively. The foundation of the coupling dynamic model provides a reference and basis on the constitution of rational processing route for a practical stainless steelmaking.

关键词： coupling dynamic model smelting reduction stainless steel crude melt converter

Inclusions for Ultra-pure Ferritic Stainless Steels Containing 21% Chromium

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Journal of Iron and Steel Research International 2013年第10期20卷 70-74页

作者： WANG Hong-po SUN Li-feng PENG Bo jiang mao-fa College of Materials and Metallurgy Northeastern University

As stabilizing elements added into ultra-pure ferritic stainless steels, niobium and titanium react with car- bon and nitrogen to form carbonitrides and have great effects on the ratio of equiaxed zone and the grain size of solidi- fication structure of ingots, which remarkably affect the quality of cold-rolled sheets. Combined with thermodynamic calculation, style and precipitation progress of inclusions in ultra-pure ferritic stainless steels were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive spectros- copy. The results indicate that the inclusions are mainly Ti-Al-N- O system inclusions in ultra-pure ferritic stainless steels. Al2Oa starts to precipitate firstly and then TiOx and TiN precipitates sequently. The inclusions are mainly single TiN particles and complex inclusions with Al2O3-Ti2O3 as cores and covered with TiN under the condition of 0.31% titanium addition and mainly Al2O3 under the condition of 0.01% titanium addition. A few （Nb,Ti）N parti- cles precipitate because of no enough titanium to react with nitrogen when titanium addition is 0.01 %. In addition, fine Nb（C, N） particles with size of less than 500 nm precipitate at relatively low temperature.

关键词： ultra-pure ferritic stainless steel ingot inclusion stabilizing element

Development of Glass Ceramics Made From Ferrous Tailings and Slag in China

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Journal of Iron and Steel Research International 2007年第2期14卷 73-78页

作者： LIU Cheng-jun SHI Pei-yang ZHANG Da-yong jiang mao-fa School of Materials and Metallurgy Northeastern University Shenyang 110004 Liaoning China

A great amount of ferrous tailings and slag cause severe damage to the ecological environment, which must be reclaimed and utilized. The composition, type, and characteristics of ferrous tailings and slag in China were introduced. The research status and the application outlook of glass ceramics made from ferrous tailings and slag were discussed. Glass ceramics made from ferrous tailings and slag can be applied to various fields, and it will be environmentally conscious materials in the 21st century.

关键词： glass ceramics ferrous tailings slag

Physical Simulation of Molten Slag Granulation by Rotary Disk

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Journal of Iron and Steel Research International 2013年第9期20卷 26-32页

作者： MIN Yi HUANG Jian LIU Cheng-jun jiang mao-fa YU Xue-qing School of Materials and Metallurgy Northeastern University Benxi Steel Group Corporation

A physical model of molten slag granulation by rotary disk was developed based on the mechanism of New-tonian liquid granulation. For geometrical similarity, the radius ratio of model disk to the prototype disk was chosen as 1 ： 1. For dynamic similarity, equality of Ohnesorge number between the model and the prototype was achieved firstly by compounding rosin and paraffin wax with mass ratio of 4 ~ 1 as simulation liquid of molten blast furnace （BF） slag, and the simulation material can satisfy the similarity of liquid solid transformation during falling in the medium; then equality of Reynolds number and Weber number was obtained by controlling the volumetric flow rate and the rotary speed, respectively. Model accuracy was verified by comparing the simulation data with the results re ported in literature, which showed good agreement with the calculation results of empirical equation and the actual molten BF slag granulation from the view point of particle size. Furthermore, influences of disk radius, rotary speed and liquid flow rate on granulation were discussed using the developed model, and the Kitamura equation was modi-fied according to the simulation data which can predict particle size more accurately. Using the modified equation, the operation parameters were predicted according to the flow rate of molten industrial BF slag.

关键词： physical model simulation liquid molten slag granulation rotary disk

Crystallization Temperature and Crystallization Ratio of Mold Flux

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Journal of Iron and Steel Research International 2005年第6期12卷 23-26页

作者： ZHU Chuan-yun HAN Wen-dian LIU Cheng-jun jiang mao-fa Northeastern University Shenyang 110004 China Central Iron and Steel Research Institute Beijing 100081 China

The factors influencing the crystallization ratio of mold flux were researched by rapid cooling technolo gy, and the factors affecting crystallization temperature were studied by single thermocouple technique. The results showed that the crystallization ratio of mold flux increases with the basicity and the content of Na2O, CaF2, Li2O and NaF, and decreases with the increase of the content of Al2O3, MgO, BaO, MnO and B2O3. However, the crystallization temperature of mold flux rises with the basicity and the content of NaF, Na2O and CaF2, and reduces with the increase of the content of Al2O3, MgO, BaO, MnO and B2O3. But for Li2O, crystallization temperature decreases firstly to a minimum value at 2%, and then increases gradually with the increase of Li2O.

关键词： mold flux crystallization temperature crystallization ratio viscosity solidification temperature

Characteristic Analysis of Solidified Crust for Basic Tundish Flux With Al-Killed Steel Casting

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Journal of Iron and Steel Research International 2011年第1期18卷 16-19页

作者： WANG De-yong ZHANG Zhi-xiang WANG Hui-hua jiang mao-fa School of Materials and Metallurgy Northeastern University Shenyang 110004 Liaoning China College of Materials Science and Engineering Shenyang University of Chemical Technology Shenyang 110142 I.iaoning China

The solidified crust was harmful to Al-killed steel casting using a basic tundish flux. After sampling from an actual tundish, XRD, SEM and EDX examinations were carried out to analyze the microstructure of solidified crusts. The conclusions were obtained as follows： main crystallization phases existing in tundish crust were Ca12 A14 O23, Ca2SiO4 and a little spinel; spinel and Ca2SiO4 distributed between the grain boundaries of Ca12 A14 Oa3, which increased the connection strength of crystallization phases by pinning grain boundary, density or hardness of solidified crust maybe also significantly increases; when initial composition of tundish flux was located in spinel region of CaO-SiO2-Al2 O3-10 % MgO phase diagram, it was easier to precipitate spinel from molten slag; three approaches of spinel formation in flux were summarized. When flux was saturated with magnesia on the metal/flux interface, MgO in flux was reduced by dissolved aluminum and then formed spinel. On the interface of steel/refractory, with feasible aluminum content, it was also easy to form spinel, and spinel inclusions will be floated and captured by tundish flux.

关键词： tundish flux solidified crust spinel formation approach