钢铁钒钛

Experimental Study on Ultrasonic-assisted Extraction of Vanadium and Chromium from High Chromium Vanadium Slag

Wen Jing, Jiang Tao, Liu Jiayi, Xue Xiangxin

2018, 39(1): 1-5. doi: 10.7513/j.issn.1004-7638.2018.01.001

Abstract(45) PDF(1)

Abstract:
In this paper,the leaching behavior of vanadium and chromium was studied by ultrasonic assisted leaching,and the optimum process parameters were obtained.The effects of ultrasonic power,leaching medium concentration,liquid-solid ratio,leaching temperature and leaching time on vanadium-chromium leaching were studied in detail. The results showed that the leaching rate of vanadium was the highest when the ultrasonic power was 560 W,the concentration of leaching medium was 10%,the ratio of liquid to solid was 7,the leaching temperature was 60 ℃ and the leaching time was 20 min,and the chromium leaching rate was the smallest,achieving the efficient extraction of vanadium and the separation of vanadium and chromium.For vanadium leaching rate,the ultrasonic power has the greatest effect on the leaching rate of vanadium,followed by liquid-solid ratio,acid concentration and leaching time. Leaching temperature has the least effect on vanadium leaching rate.For the leaching rate of chromium,the leaching rate of chromium was less than 1%,and the ultrasonic power had the least effect on the leaching rate of vanadium,and the acid concentration had the greatest effect on the leaching rate of chromium.

Measurement of Calcification of Vanadium Slag by XRD Semi-quantitative Method

Wang Minghua, Liu Zhenhui, Zhao Hui, Liu Yan, Lou Taiping, Sun Zhaohui, Tang Hongjian, Jing Han

2018, 39(1): 6-12. doi: 10.7513/j.issn.1004-7638.2018.01.002

Abstract(40) PDF(1)

Abstract:
Calcification roasting process of vanadium slag is just currently situated at pilot stage of industrialization in China,while the recovery ratio of vanadium from vanadium slag is only 69.7%.It is not clear so far whether the calcification or leaching process leads to the low recovery ratio. This paper studied the factors influencing calcification ratio directly by XRD（X-ray diffraction） semi-quantitative method. Experimental results show that calcification ratio of vanadium slag increases with rise of CaO and V₂O₅ content while decreases with increase of temperature.Fe[Ⅲ]V[Ⅴ]O₄ can be formed at exorbitant temperatures leading to a decrease in calcium vanadate content of the product. A highest calcification ratio of 100% can be obtained at 790℃ for 8 h with material containing 50% of CaO,25% of V₂O₅,total 25% of Cr₂O₃,SiO₂,and Fe₂O₃.From SEM results,it indicates that block calcium vanadate possessing smooth surface is mixed with calcium chromate,ferric chromate,ferric vanadate,ferric oxide and silicates. The research proves that present low recovery ratio of vanadium is due to the low efficiency of leaching rather than calcination,which provides a new insight for the production.

Mineralogical Characteristics of Vanadium Slag

Wang Ling, Cui Zhaochun, Zhang Yuxi, Li Cunguo, Bai Wangmin, Li Zhiwei, He Peng

2018, 39(1): 13-17. doi: 10.7513/j.issn.1004-7638.2018.01.003

Abstract(100) PDF(7)

Abstract:
The mineral and chemical compositions,occurrence and distribution of the valuable elements,the structure and tectonics of vanadium slag were characterized by X-ray powder diffraction,optical microscope,X-ray fluorescence,scanning electron microscopy and energy dispersive spectrum,aiming to provide a theoretical foundation for efficient and clean utilization of vanadium slag.It is suggested that the vanadium slag is composed of vuorelainenite,fayalite,augite,metallic iron and a small amount of quartz. The crystalline grains of vuorelainenite are fine and encompassed by the silicates,difficult to be separated and enriched physically.The main valuable elements are Fe,V and Ti with considerable Cr and Mn.V and Cr primarily exist in vuorelainenite while Fe,Ti and Mn are distributed both in vuorelainenite and silicates.Hence,to realize an efficient recovery of vanadium slag,simultaneous utilization of vuorelainenite and silicates minerals in the slag should be taken into consideration.

Influence of Post-processing on Brightness of Titanium Dioxide

Wang Haibo

2018, 39(1): 18-23. doi: 10.7513/j.issn.1004-7638.2018.01.004

Abstract(67) PDF(4)

Abstract:
In order to solve the problem of low brightness and brightness fluctuation for titanium dioxide（TiO₂） produced by a certain plant,a systemic investigation related to influences of the raw materials and process of post-processing on brightness of TiO₂ was carried out in basis of industrial conditions. The results show that a narrow particle size distribution（250 ~260 nm of average size for initial TiO₂）,sphereapproximate morphology and intermediate crushing dispersant able to decrease the viscosity of inorganic surface treatment system,are beneficial to brightness improvement of TiO₂. Organic agents have no effect on TiO₂ brightness,and a better smash and dispersion effect of intermediate crushing can help to improve the brightness.The inorganic surface treatment increases the brightness by about 0. 18. Furthermore,flash drying treatment and the addition of organic agent into steam powder have basically no impact on the brightness of TiO₂. However,it suffers from carbonization of the organic treatment agent at temperatures higher than 180 ℃ for long hours,which has an adverse effect on the brightness of TiO₂.

Preparation of Titanium Powder by Reduction of TiO₂ at Low Temperature with CaH₂

DENG Bin

2018, 39(1): 24-30. doi: 10.7513/j.issn.1004-7638.2018.01.005

Abstract(124) PDF(3)

Abstract:
A new method for preparing Ti powder by thermal reduction at low temperature was explored with industrial titanium dioxide（TiO₂） powder and AR（Analytical Reagent） calcium hydride（CaH₂）powder as raw materials.The decomposition conditions of CaH₂ and the process for reduction of TiO₂ by decomposed CaH₂ were studied by reaction thermodynamics calculations and experiments.The results show that vacuum conditions can reduce the decomposition temperature of CaH₂,and CaH₂ is decomposed into Ca and H₂ at 890.7 K for 1 h with 2.5 Pa of initial vacuum degree.TiO₂ is stepwise reduced by Ca decomposed from CaH₂,and the intermediate products such as Ti_nO_{2 n-1} and CaTiO₃can be finally reduced into Ti at temperatures higher than 993 K for 3 h.H residual in Ti powder can be efficiently removed by distilling the products at reaction terminal.The obtained Ti powder is of irregular block shapes with a median size of 1.83 μm,satisfying the composition requirements for TF-2 grade of Ti powder according to the industrial standard YS/T 654-2007.

Study on the Influence Factors for Titanium Formation on Reactor Wall during Titanium Sponge Production by Kroll Process

SHENG Zhuo

2018, 39(1): 31-34. doi: 10.7513/j.issn.1004-7638.2018.01.006

Abstract(85) PDF(2)

Abstract:
In this paper,the microstructure of titanium formed on the reactor wall during titanium sponge production by Kroll process was investigated to further analyze the growth process of wall-adherent titanium and its influencing factors for accumulation.The results show that the generation of wall-adherent titanium cannot be averted,and its accumulation is determined by the variation of vertical height for reaction interface before and after MgCl₂ discharge,the height of liquid magnesium on reactor wall and gaseous TiCl₄ content in reactor.

Exploring the Relationship of Structure and Electrochemical Activity of V（Ⅲ） Ion in Vanadium Electrolyte

Xu Jie, Fan Chuanlin, Yang Haitao, Zhu Qingshan

2018, 39(1): 35-39. doi: 10.7513/j.issn.1004-7638.2018.01.007

Abstract(201) PDF(5)

Abstract:
All-vanadium redox flow battery（VRFB） is one of the most promising large-scale energy storage technologies,owing to its inherent safety and long service life.During the charging-discharging process,the redox reaction of V（Ⅲ）↔V（Ⅱ） with standard electrode potential of-0.25 V（vs.NHE） is the main electrochemical reaction in negative electrolyte.The side reaction of hydrogen evolution would take place with low electrochemical activity of V（Ⅲ） ion,which will degrade VRFB performance.In present work,to explore the relationship of structure and electrochemical activity of V（Ⅲ） ion,the quantum chemistry calculation and activity analysis of V（Ⅲ） ions with various structures were conducted with the MP2 theoretical method and LANL2 DZ basis using the Gaussian software.Combining to the experimental results of electrochemical activity,the low electrochemical activity of V（Ⅲ） ion in fresh prepared electrolyte was found due to their hydrolytic polymerization.,The polymerization can be reduced by 5 cycles of charge and discharge,which leads to a high electrochemical activity of V（Ⅲ） ion and inhibition of hydrogen evolution.But the electrochemical activity of activated electrolyte will obviously reduce after 40 days’ standing at room temperature,indicating that the hydrolytic polymerization of V（Ⅲ） ions in negative electrolyte may be spontaneous.

Research on Calculation Method for Hydrogen Induced Stress Corrosion Fracture Toughness of Metal in Deep Sea

Xi Qiang, Zheng Bailin, He Pengfei, Yang Biao, Li Yanqing

2018, 39(1): 40-45. doi: 10.7513/j.issn.1004-7638.2018.01.008

Abstract(131) PDF(6)

Abstract:
Focusing on the hydrogen induced stress corrosion cracking（HISCC） of titanium alloy in deep sea,this paper calculated hydrogen diffusion in metal with the stress induced diffusion method and introduced the hydrogen reducing surface energy model into HISCC process to simulate the cycling of the material embrittlement of crack tip and crack propagation by finite element software ABAQUS combined with the secondary development of Python.Calibrated with the experiment in existing literature,the calculation error is 11%,which proves that the method for updating the critical fracture surface energy of the crack tip at the beginning of each crack is effective and feasible.The results show that,hydrogen will concentrate on the crack tip where the stress is relatively higher,and the environmental pressures will intensify this process.The HISCC fracture toughness of a titanium alloy at 5 000 and 10 000 depth reduces to 31.16%and 22.28% of that in the indoor environment,respectively.

Research on Dry Sliding Wear Performances of Hot-dip Aluminized TC4 Alloy

Chen Wei, Wang Haohao, Guo Menglei, Jiang Wei, Wang Shuqi

2018, 39(1): 46-50. doi: 10.7513/j.issn.1004-7638.2018.01.009

Abstract(57) PDF(1)

Abstract:
The aluminized TC4 alloy was prepared by hot-dip aluminizing and subsequently high-temperature annealing treatment. The morphology,phase and compositions of aluminized coating were characterized with SEM,XRD and EDS.Dry sliding wear behaviors at different velocities and loadings were conducted for the aluminized and uncoated TC4 alloy on a pin-on-disc wear tester,and the wear mechanism was also explored.The results show that the coating is mainly composed of TiAl₃ combined well to the substrate with a smooth surface. Compared with uncoated TC4 alloy,the aluminized coating has a more excellent wear resistance at sliding velocities of 0.5 ~4 m/s under the same loads.The aluminized and uncoated TC4 alloy present a similar variation of wear rate as a function of velocity.At 0.5 ~0.75 m/s,the wear rate first decrease and then increase rapidly,reaching the top value at 2.68 m/s.Furthermore,the wear rate decreases again from 2.68 to 4 m/s.The main wear mechanism at 0.75 m/s is adhesive wear and abrasive wear,while it is delamination wear at 2.68 m/s and slightly oxidative wear at 4 m/s.

Preparation of TiN by Reaction between Mg₃N₂ and TiCl₄

Zhu Fuxing

2018, 39(1): 51-55,59. doi: 10.7513/j.issn.1004-7638.2018.01.010

Abstract(65) PDF(2)

Abstract:
Preparation of Ti N via reaction of Mg₃N₂ and TiCl₄,and its yield ratio were studied respectively through XRD,SEM and orthogonal experiments.The results show that TiN can be obtained by the reaction of Mg₃N₂ and TiCl₄,and the product is of irregular morphology with nonuniform particle size.The reaction equation can be described as.A decreasing sequence for influence factors of TiN yield rate is the speed of TiCl₄ addition,temperature and molar ratio of TiCl₄ to Mg,respectively.73.7% of Ti N can be yielded at the optimum conditions of 600 ℃ with 0.1 L/min of TiCl₄ addition speed and equimolar of TiCl₄ and Mg.

Ultrasonic Casting Process Optimization of Vanadium-based Hydrogen Storage Alloy

Zheng Xin, Yang Yuling, Liu Ronghai

2018, 39(1): 56-59. doi: 10.7513/j.issn.1004-7638.2018.01.011

Abstract(31) PDF(1)

Abstract:
Ultrasonic casting of V₃Ti_0.56Cr_0.1Mo_0.1 vanadium-based hydrogen storage alloys was carried out at different ultrasonic vibration frequencies and pouring temperatures,and the hydrogen storage property and electrochemical cycling stability of the samples were tested and analyzed.The results show that compared with 95 Hz,ultrasonic vibration frequency at 55 Hz can increase the maximum hydrogen absorption of the sample by 65% and reduce the decay rate of discharge capacity by 61%.Compared with 1 830 ℃,pouring temperature at1 920 ℃ can increase the maximum hydrogen absorption of the sample by 71% and reduce the decay rate of discharge capacity by 63%.Both of the hydrogen storage property and electrochemical cycling stability of the samples first increase and then decline with increase of ultrasonic vibration frequency and pouring temperature.The optimized ultrasonic vibration frequency and pouring temperature of V₃Ti_0.56Cr_0.1Mo_0.1 vanadium-based hydrogen storage alloy are 55 Hz and 1 920 ℃,respectively.

Current Research Status and Development of High-temperature Titanium Alloys

Huang Dong, Yang Shaoli, Ma Lan, Liao Xin, Piao Rongxun

2018, 39(1): 60-66. doi: 10.7513/j.issn.1004-7638.2018.01.012

Abstract(595) PDF(33)

Abstract:
In this paper,the development and present application of high-temperature titanium alloys were introduced.The research status and influence of alloying elements on high-temperature titanium alloys domestic and abroad were contrasted and analyzed.Titanium alloys with 600℃ of working temperature mainly include Ti1100 in USA,British IMI834,Russian BT18 and BT36,Chinese Ti60 and Ti600. Combined with the research focus on high-temperature titanium alloys,it was found that two key factors of creep resistance and oxidation resistance should be improved at higher than 600 ℃ of working temperature,for a stable and long-time operation of titanium alloys.The major research orientation for high-temperature titanium alloys in future was proposed to be preparation of particle-reinforced titanium-based composites and improvement of Ti-Al alloys using 3 D printing technologies.

Effect of Microwave on the Treatment of Gaseous Solid-state Low-cyclic PAHs in Coke Flue Gas

Shi Yan, Zhao Xin, Guan Wei, Feng Yingying, Zhao Ying, Hao Suju

2018, 39(1): 67-71. doi: 10.7513/j.issn.1004-7638.2018.01.013

Abstract(37) PDF(1)

Abstract:
The polycyclic aromatic hydrocarbons（PAHs） were collected from absorbing media of activated carbon and silicon carbide by dichloromethane and glass fiber. Ultrasonic extraction and high performance liquid chromatography（HPLC） were used to qualitatively and quantitatively analyze the low cyclic polycyclic aromatic hydrocarbons,and the effects of microwave temperature,quality of silicon carbide,mass and particle size of activated carbon on the degradation of low rings polycyclic aromatic hydrocarbons were investigated. The experimental results show that activated carbon and silicon carbide have a certain effect on the treatment of polycyclic aromatic hydrocarbons（PAHs） as microwave absorbing media and microwave,and the treatment effect of polycyclic aromatic hydrocarbons is better than that of gaseous polycyclic aromatic hydrocarbons. Compared the two kinds of absorbing media,silicon carbide have the better treatment effect on the gaseous polycyclic aromatic hydrocarbons and solid state polycyclic aromatic hydrocarbons.

Effect of Nucleating Agent on Crystallization Behavior and Kinetics of Blast Furnace Slag Glass Ceramics

Gao Yang, Gui Yongliang, Song Chunyan, Hu Binsheng, Wang Yawen

2018, 39(1): 72-77. doi: 10.7513/j.issn.1004-7638.2018.01.014

Abstract(91) PDF(2)

Abstract:
Taken Tangshan iron and steel blast furnace slag as the main raw material,Cr₂O₃,TiO₂,Fe₂O₃ and P₂O₅ nucleating agent had been added with a certain proportion of other raw materials,and the blast furnace slag microcrystalline glass had been prepared by melting method. Differential thermal analyzer（SEM） and electron scanning microscope（SEM） were used to investigate the effect of nucleating agents on the crystallization behavior of glass ceramics. The results show that 2% Cr₂O₃ and 8% P₂O₅ can form microcrystalline glass with fine grain and uniform distribution. Addition of 8% TiO₂ and 6% Fe₂O₃ can not result in an ideal microcrystalline glass.

Analysis on the Mechanism of Direct Reduction of Limonite by Coke Quenching Ash as Reducing Agent

Chen Weipeng, Wang Qiang, Feng Zhiming, Chen Xiaodan, Zhao Zengwu, Wu Wenfei, Li Baowei

2018, 39(1): 78-83. doi: 10.7513/j.issn.1004-7638.2018.01.015

Abstract(38) PDF(5)

Abstract:
The reaction mechanism of low-grade limonite powder in the process of heating with different carbon-oxygen ratio was revealed by thermal analysis at temperature of 20 ~1 100 ℃,using coke quenching ash as a new reducing agent.The effects of different carbon ratios on the reaction rate were studied.The experimental results showed that proper excess carbon accelerates the redox.The reaction system was carried out in the two-step reaction mechanism of solid-solid reaction and gas-solid reaction during the heating process,the speed of carbon gasification is very sensitive to temperature,and is the controlling link of the whole reduction reaction.And 635.2 ℃ is the initial carbon reduction temperature,while the temperature is higher than 919.5 ℃,the reduction of iron oxide mainly by direct reduction of CO.After the end of the experiment,the reduction products with carbon-oxygen ratio of 1.2 was analyzed by scanning electron microscopy（SEM）,and It was found that the iron of the reduction product was evenly dispersed,and the iron slag phase boundary was distinct.Through X-ray diffraction（XRD）,it was found that no iron oxide diffraction peak was found in the reduction products,and the iron metal diffraction peak was obviously.

Thermodynamic Analysis on Effects of Chemical Composition on Mineral Composition in Medium-titanium Blast Furnace Slag

Zhang Shuhui, Yan Zhaozhao, Liu Xiaojie, Dong Xiaoxu, Lü Qing, Lan Chenchen

2018, 39(1): 84-91. doi: 10.7513/j.issn.1004-7638.2018.01.016

Abstract(62) PDF(2)

Abstract:
The equilibrium mineral components in the crystallization process of medium-titanium blast furnace slag are calculated by using FACTSage 7.0 thermodynamics software,and the influence of different chemical composition on mineral precipitation process and mineral composition of medium-titanium blast furnace slag are analyzed. The results show that in the cooling process of medium titanium blast furnace slag,the precipitation phases mainly are melilite,perovskite,spinel and diopside. There is no single perovskite phase existing in the slag when alkalinity is low（R＜0.93）; when the basicity is more than 1.03 and continues to increase,the content of melilite increases,however,the content of spinel is lower.The higher alkalinity is more conducive to form the perovskite. Due to the increase of TiO₂ content,the content of melilite on medium-titanium slag decreases with increasing perovskite content. And with the temperature decreasing,the titanium enriches into titania spinel firstly,and finally moves into perovskite phase. The mineral precipitation process becomes more complicated with the increase of MgO or Al₂O₃ content in the slag,which has an significant influence on the precipitation of titanium.

Study on the Relationship between Carbon Consumption and Direct Reduction of Iron in Low Grade Ore

Yan Shuai, Huang Bangfu, Liu Jiangwei, Wang Weiwei, Zheng Jingqiang

2018, 39(1): 92-96. doi: 10.7513/j.issn.1004-7638.2018.01.017

Abstract(92) PDF(6)

Abstract:
In the blast furnace smelting,the consumption of carbon is determined by the sum of the calorific carbon consumption and the carbon loss of the reduction reaction.During the smelting process,as the direct reduction of iron rdincreases,the direct reduction carbon consumption increases,and as the reaction consumes a lot of heat,calorific carbon consumption should also increase,causing a high production costs.Therefore,reducing the rdvalue as low as possible,in order to reduce carbon consumption and reduce costs during smelting process. In this paper,the relationship between carbon consumption,gas utilization rate and iron direct reduction degree is obtained by calculating the carbon consumption and iron reduction degree of low grade ore blast furnace. Combined with the actual smelting,the furnace material selection,smelting conditions and other aspects of improvement measures for the blast furnace smelting had been proposed to reduce costs and provide the reference for energy conservation.

Study of Slag Forming Path During Dephosphorization and Vanadium-extraction from Vanadium-containing Hot Metal

CHEN Lian

2018, 39(1): 97-102,123. doi: 10.7513/j.issn.1004-7638.2018.01.018

Abstract(39) PDF(2)

Abstract:
Processing slag and ending slag of vanadium-extraction converter was analyzed and the slag formation and the existing form of phosphorus in the slag had been investigated. It is found out that addition of lime into the vanadium-extraction converter during production can achieve dephosphorization from molten iron,and oxidation of vanadium and phosphorus do not affect each other,but the stirring intensity of the furnace shall be increase to achieve effectively remove phosphorus.

Study on Adsorption Capacity of Adsorption Bar under Multi-factors

Wang Yufei, Zhao Dingguo, Gao Ming, Wang Shuhuan

2018, 39(1): 103-110. doi: 10.7513/j.issn.1004-7638.2018.01.019

Abstract(29) PDF(1)

Abstract:
The refractory absorption bar is inserted into the submersed nozzle by stopper to absorb the inclusion flowing through the nozzle and the cleanness of liquid steel during the continuous casting process can be improved. The influence of the depth of groove,the direction of rotation and the number of grooves on the adsorption capacity of absorption bar was analyzed by high temperature thermal experiment. The results show: Adsorption bars of different structures have different chemical adsorption effects on inclusions of different sizes in molten steel. When the selection of groove depth,groove direction and groove number are combined,for the ＜5 μm,10 ~20 μm inclusions,the absorption bar has the best removal effect when the number of grooves is 3,the groove depth is 2 mm the groove is parallel to the rotation direction,and the inclusions are located in the middle of the sample. For the 5 ~10 μm,＞ 20 μm inclusions,the absorption bar has the best removal effect when the number of grooves is 3,the groove depth is 2 mm,the groove is parallel to the rotation direction,and the inclusions are located in the edge of the sample.Under the same structure,the chemical adsorption of inclusions of different sizes in molten steel is more favorable when the groove of the absorption bar is in parallel rotating direction. This experiment has provided data support for smelting clean steel.

Study on the Mold Flow State Influenced by Two-hole Nozzle

Liu Yi, Zhang Caijun, Wu Zhe

2018, 39(1): 111-117. doi: 10.7513/j.issn.1004-7638.2018.01.020

Abstract(70) PDF(1)

Abstract:
The particle image velocimetry-PIV technique was used to study the factors affecting the flow state in the continuous casting mold.i With the increase of casting speed,the distance of narrow face impact point to level decreases,and difference in the level flow velocity decreases,resulting in the flow state tending to be symmetric. With increasing immersion depth,the position of stream impact to narrow face tends to be symmetrical,and the level flow velocity reduces,then level fluctuation decreases. It is concluded that suitable immersion depth of nozzle plays an important role in stabling mold flow.Nozzle clogging has a significant influence on the flow field in the mold.With the degree of right nozzle clogging increasing,the flow velocity,flow angle and position of narrow impact on both sides of nozzle present asymmetric.Large difference in the surface velocity causes high frequency of eddy current occurrence,and then producing volume slag,uneven solidification or cold-shut.Therefore,measures such as hydrogen blowing should be adopted to reduce the incidence of nozzle clogging.

Key Technologies of Macro Segregation Control in 320 mm×410 mm Continuous Casting Bloom for Railway Steel

Chen Liang, Song Bo, Chen Tianming, Li Yangzhou, Li Zhiqiang, Li Jianquan

2018, 39(1): 118-123. doi: 10.7513/j.issn.1004-7638.2018.01.021

Abstract(82) PDF(8)

Abstract:
The electromagnetic stirring,total amount of soft reduction and the matching between super heat and casting speed were researched in order to control carbon segregation index of transverse section and center segregation in rail steel bloom. The key technologies of segregation control in 320 mm×410 mm continuous casting bloom for railway steel had been established. The best parameters for continuous casting rail steel from this investigation are as follows: intensity and frequency of mold electromagnetic stir current are 600 A and 2.4 Hz,intensity and frequency of final electromagnetic stir current are 330 A and 7 Hz,total reduction of soft reduction is ranged from 9 mm to 12 mm,superheat is ranged from 20 ℃ to 35 ℃ and the casting speed is ranged from 0.70 m/min to 0.72 m/min. Based on these parameters,the resulted bloom has a high quality where the center equiaxial crystal is 41.2% on average,the rate of center segregation less than 0.5 is 85%,and the carbon segregation index of transverse section ranges from 0.95 ~1.07. The quality of bloom meets the standard requirements for rail production.

Solidification Structure Optimization of 304 Stainless Steel

Wu Qingyu, Zhao Jing, Lü Junjie, Zhao Ziyu

2018, 39(1): 124-129. doi: 10.7513/j.issn.1004-7638.2018.01.022

Abstract(51) PDF(5)

Abstract:
In order to reduce the crack of 304 austenitic stainless steel pipe,the experiments of composition optimization,F-EMS and superheat controlling have been done to optimize solidification structure.The area fraction of δ ferrite in structure of billet center decreases from 8.6 % to 7.2 % through composition optimization. By implement of F-EMS,The area fraction of δ ferrite in structure of billet center decreases to 5.8 % and distributes dispersively,the δ ferrite in the billet without F-EMS is net-like. The superheat between 30 ℃ and 40 ℃ is beneficial to reduce δ ferrite. The amount of δ ferrite in 304 billets decreases significantly by using above measures and the crack during piercing is improved significantly.

Effect of Composition on Solidification Structure of Low Carbon Steel Based on CAFE Method

Wen Juwen, Zhu Liguang, Zhang Yuanjie, Yang Gaiyan, Liu Yi

2018, 39(1): 130-135. doi: 10.7513/j.issn.1004-7638.2018.01.023

Abstract(40) PDF(1)

Abstract:
The composition of steel is an important factor affecting the solidification structure of slab.In this paper,the influence of the composition of low carbon steel Q235 on the solidification structure is studied based on the CAFE method. The increase of C content and the increase of C content make the equiaxed grain rate increase and the C content is 0. 22%. With the Si content increasing,the number of equiaxed grains increases firstly and then decreases The number of equiaxed grains in the structure decreases with the increase of Mn content,and the change of Mn content has little effect on the number of equiaxed grains.

Surface Transversal Crack on S355ML Beam Blank

Zhao Pengze, Sun Yanhui, Dong Jian, Wu Baoqiao, Wang Houxin

2018, 39(1): 136-142. doi: 10.7513/j.issn.1004-7638.2018.01.024

Abstract(36) PDF(1)

Abstract:
The causes of surface transverse crack on S355 ML beam blanks had been investigated by metallographic,SEM,TEM observations and nozzle flow field analysis,in combination with thermal imaging temperature of continuous casting billet. Results show that the flow field distribution of through-type nozzle is unsuitable. The surface of beam blank exist great temperature gradient,especially from top of flange to the web R Angle,thus profiled billet fall in brittle zone during straightening. Furthermore,lots of carbonitride precipitation in S355 ML shaped blank damage high temperature ductility of steel,and thus increase the slab crack sensitivity. By optimizing secondary cooling system and controlling composition at narrow range,the billet can be avoided to fall in Ⅲ brittle zone when being straighten and then slab surface quality can be improved.

Analysis of IAF Nucleation and Grain Refinement Behavior in EH460 Steel

Qin Shuyang, Liu Zengxun, Wang Shuoming, Zhu Liguang

2018, 39(1): 143-147. doi: 10.7513/j.issn.1004-7638.2018.01.025

Abstract(45) PDF(1)

Abstract:
The structure,composition,particle size of micro-inclusions in laboratory as-cast shipbuilding steel with different content and type of elements were analyzed. It was found out that some kinds of inclusions in steel can induce nucleation of IAF and the needle tip of IAF can insert into other ferrite grains or pearlite and thus splitting it into several smaller units in the process of growth,resulting in significant grain refinement. The component of inclusions capable of inducing IAF nucleation in the steel are mainly Al₂O₃-Ti₂O₃、Al₂O₃-Ti₂O₃-MnO/MnS、Al₂O₃-Ti₂O₃-MnO/Mn S-SiO₂ composite deoxidation inclusions,and their particle size was 1.0 ~10 μm. 89.3% of the inclusions are between 1.0 ~6.0 μm,about,and the rest 10. 7% are between 6. 0 ~10. 0 μm. By controlling the types of alloy elements and adding sequence,a large number of fine inclusions which can induce intensive IAF nucleation can be produced and then achieve grain refinement.

Comparison of Quality between C70S6 Steels Produced by Chinese and Oversesa Steelmakers for Fracture Splitting Connection Rod

Deng Xiangyang, Li Jian, Xie Jianbo, Hu Delin, Wang Yang, Fu Jianxun

2018, 39(1): 148-154. doi: 10.7513/j.issn.1004-7638.2018.01.026

Abstract(134) PDF(4)

Abstract:
Cracking technology requires materials with advanced performances of high strength,low toughness,well-cutting and small plastic deformation during brittle fracture.The C70 S6 steel is an important material for fracture splitting connection rod.The steels produced by Chinese and overseas steelmakers had been compared in terms of their comprehensive performance.The samples of Chinese steel have higher sulfur and manganese content,while nickel,vanadium,titanium content are lower. All samples have same microscopic structures comprising lamellar pearlite and small amount of ferrite.However,overseas samples have smaller grain size and lower ferrite amount.Besides,for overseas samples,the sulfide is in form of spindle and distributes evenly in matrix,and amount of complex inclusions is higher. For Chinese samples,the sulfide in long-strip state distributes uniformly and the amount of complex inclusions is smaller.

Numerical Simulation of Spray Angle in the Process of Atomization Process of SmFe Melt

Wang Shuhuan, Cui Shaopu, Sun Xin, Zhao Dingguo, Fang Yunchu, Song Chunyan

2018, 39(1): 155-159. doi: 10.7513/j.issn.1004-7638.2018.01.027

Abstract(42) PDF(2)

Abstract:
To explore the influence of spray angle on the atomization process of Sm Fe melt,the structure of nozzle based on the close-coupled nozzle,the atomization process of Sm Fe melt has been simulated using Fluent,and the influence of different spray angles on the flight distance before solidification of atomized droplets and droplet breakup degree had been analyzed. The results show that when the spray angle increases,the flight distance before solidification of droplets decreases,at 45 degrees flight distance is the minimum,then there is an increasing trend after 45° spray angle.When the spray angle increases,the SMD firstly decreases,and the SMD is the smallest at 45 degrees,which is about 7.58 μm,and the breakup of the droplets is the best,and then it increases when spray angle exceeds 45°. Considering the atomization effect,when the spray angle is 45 degrees,flight distance of droplet is the shortest at 14.66 mm,the SMD is the smallest,and the breakup of the droplets is the best.

Production Practice of Process Optimization of 780 MPa Cold Rolled Dual Phase Steel

Li Xia, Wang Xigang

2018, 39(1): 160-164. doi: 10.7513/j.issn.1004-7638.2018.01.028

Abstract(63) PDF(2)

Abstract:
In order to obtain excellent mechanical property of 780 MPa cold rolled dual phase steel,process optimization had been done including adjusting the chemical elements C、Si、Nb、Ti、Cr and coiling temperature.And the microstructure observation and mechanical properties measurement of hot and cold rolling strip had been performed.It is found out that alloying design of 0.12%C+0.39%Si+0.25% ~0.60% Nb+Cr and suitable coiling temperature below 660 ℃ can generate desired microstructure and mechanical properties.And optimal ratio of yield to tensile strength and the product of tensile strength and elongation of 18 318 MPa·% had been achieved.

FEM Analysis and Pass System Optimization of 16^#Ⅰ Beam during Rolling

Tang Rui, Zhang Zheng, Xie Yongchun

2018, 39(1): 165-168. doi: 10.7513/j.issn.1004-7638.2018.01.029

Abstract(56) PDF(1)

Abstract:
In this paper FEM software were used to simulate rolling process of conjugated pass system of some enterprise,bend and twist of rolled piece during rolling had been identified. The reasons which caused these problems had been found out by quantification and transformation analysis,and optimization of pass parameters had been conducted based on common central roll rolling process. Using FEM to verify optimized pass,and the result indicated that the problems had mainly solved and optimized pass can be used in actual production.

2018, 39(1): 169-170.

Abstract(41) PDF(2)

Abstract:

2018 Vol. 39, No. 1