钢铁钒钛

Changes in Occurrence State of Ti,Si and Al Elements in Ti-bearing Blast Furnace Slag during Alkali Melting Process

He Siqi, Wang Yan, Sun Hongjuan, Peng Tongjiang

2017, 38(1): 1-7. doi: 10.7513/j.issn.1004-7638.2017.01.001

Abstract(10) PDF(1)

Abstract:
By sodium hydroxide melting process,separation of components from Ti-bearing blast furnace slag in Panzhihua was conducted in this paper. The chemical reaction processes of the original mineral phase and intermediate products at different temperatures were investigated by analyzing the structure and spectroscopic characteristics of the alkali melting slag and water leaching slag formed at different reaction stages,revealing the changes in occurrence state of the components in Ti-bearing blast furnace slag during the alkali melting process. The results show that at 283 ℃ the diopside phase in the slag is damaged,and the soluble salt Na₂SiO₃ and intermediate product CaMgSiO₄ can be formed due to the reactions between Si⁴⁺ and NaOH. With the reactions progressing,Ca MgSiO₄ further reacts with NaOH to generate insoluble Na₂CaSiO₄. When the reaction temperature is up to 296 ℃,the Si⁴⁺ in magnesia-alumina spinel reacts with NaOH to form Na₂SiO₃. When the alkali fusion temperature is 320 ℃,perovskite phase begins to decompose,and Ti⁴⁺ reacts with NaOH to generate insoluble Na₂TiO₃,which remains in the leaching slag as amorphous structure after Na₂TiO₃structure is destructed by water leaching.

Study on Transformation of Perovskite into Pseudobrookite in Ti-bearing Blast Furnace Slag

Zhang Qiang, Liang Bin, Lü Li, Liu Weizao, Ma Xueyang, Li Chun

2017, 38(1): 8-14. doi: 10.7513/j.issn.1004-7638.2017.01.002

Abstract(26) PDF(1)

Abstract:
The reaction system in which the titanium component transforms into pseudobrookite （Fe₂TiO₅） by sulfating decomposition of perovskite （CaTiO₃） was analyzed.The results show that the transformation can be completed through one step by introducing SO₂+O₂mixed gas into the CaTiO₃/FeSO₄ reaction system.Based on the analysis,an experimental investigation was conducted with focus on the influences of reaction temperature,reactants molar ratio,SO₂ concentration and reaction time on the sulfating reaction.It is indicated that 92% titanium component in perovskite transforms into pseudobrookite with reaction at 1 473 K for 120 min,25% （v/v） of SO₂ concentration and 1 ∶ 2.1 of molar ratio for CaTiO₃/Fe SO₄.The sulfating reaction mechanism changes with temperature. Perovskite is decomposed through the reaction CaTiO₃+SO₂+1/2O₂= CaSO₄+TiO₂ at 973-1 373 K and CaTiO₃+SO₂+ 1/2O₂+Fe₂O₃= CaSO₄+Fe₂TiO₅ at 1 473 K.

Study on Preparation of High-purity V₂O₅ by Solvent Extraction from Acid Leaching Vanadium-containing Solution

Tang Hongjian, Zhang Li, Sun Zhaohui, Chen Haijun, Yu Bin, Du Guangchao

2017, 38(1): 15-21. doi: 10.7513/j.issn.1004-7638.2017.01.003

Abstract(26) PDF(4)

Abstract:
According to characteristics of low vanadium concentration and multitudinous impurities for the sulphuric acid leaching solution of vanadium slag roasted with calcium components,high-purity vanadium pentoxide （V₂O₅） was prepared by solvent extraction from the acid leaching vanadium-containing solution. The processes of extraction,washing,stripping and acidic precipitation of vanadium by ammonium salt were systematically researched in order to explore a completely clean and efficient method for extracting vanadium from acid leaching vanadium-containing solution and provide data support for the development and application of high-purity V₂O₅ preparation technology. The results show that V₂O₅ with 99.991 5% of purity can be obtained and the recovery rate of vanadium for the whole process is up to 88.78% under the optimal conditions.

Experimental Study on Reduction of Vanadium Oxides in Blast Furnace Hearth

Yan Chaojie, Chen Shujun, Zhao Xiaojie, Li Fumin, Lü Qing, Qie Yana

2017, 38(1): 22-26,37. doi: 10.7513/j.issn.1004-7638.2017.01.004

Abstract(37) PDF(1)

Abstract:
The reduction of vanadium oxides in the blast furnace hearth has an important influence on the yield of vanadium.The effects of slag composition and temperature on the reduction of vanadium oxides were studied.The effect of binary basicity was significant on the reduction of vanadium oxides and the reduction rate of vanadium oxides increased with increase of the binary basicity.The reduction rate of vanadium oxides increased firstly and then decreased when the contents of Al₂O₃ and MgO increased.The reduction rate of vanadium oxides decreased with increasing TiO₂ content,and a significant decrease in the reduction rate of vanadium oxides occurred once the content of TiO₂ exceeded 11%.With increase in temperature,the reduction rate of vanadium oxides increased.An optimum reduction efficiency can be obtained with about 90% of reduction rate for the vanadium oxides at 1 500 ℃ of temperature and 1.2 of binary basicity for blast furnace slag,and 14% of Al₂O₃ content,10% of MgO content and 9% of TiO₂ content in the slag.

Study on Efficient Recovery Process of Fine Grained Ilmenite in Panxi Area

Wang Hongbin

2017, 38(1): 27-30. doi: 10.7513/j.issn.1004-7638.2017.01.005

Abstract(13) PDF(1)

Abstract:
According to the problem that the grade and recovery rate of fine grained ilmenite in Panxi area cannot be satisfied simultaneously by high gradient strong magnetic separator,a separation process combined with flotation using the suspension-vibration conical concentrator and high gradient strong magnetic separator as the enrichment equipment for flotation raw material was carried out in laboratory. The results show that the content of-19 μm slime,which interferes the flotation,in the flotation raw materials by the process with suspension-vibration is lower than that of the materials by process with singular magnetic separation. The combined process of suspension-vibration and flotation has an optimum recovery of fine grained ilmenite containing 10.57% TiO₂,which can obtain qualified titanium concentrate containing 47.20% TiO₂,with 13.29% of yield rate and 60% of recovery rate for TiO₂,respectively.

Beneficiation Technology Study on a Fine High-sulfur Magnetite Ore from Shanxi

Ren Taian, Huang Hongjun, Xiao Jun, Li Kaiyun, Dong Yanhong

2017, 38(1): 31-37. doi: 10.7513/j.issn.1004-7638.2017.01.006

Abstract(22) PDF(1)

Abstract:
According to the characteristics of a micro-fine magnetite from Shanxi that a part of magnetite is interbedded interactive disseminating in the micro-fine gangues with a high sulfur content resulting in difficulty for processing,a technological process including rough crashing for raw ore and tailings discarding by magnetic pulley-tailings discarding by magnetic separation-regrinding for the magnetic rough concentrate for desulphurization by flotation-magnetic concentration for flotation tailings was proposed based on the process mineralogy studies. The whole process test can obtain the iron concentrate containing 65.15% of iron and 0.11% of sulfur with 73.10% of iron recovery rate and sulfur concentrate containing 25.12% of sulfur with 30.67% of sulfur recovery rate.

Preparation of Nano-TiC Powders by In-situ Carbothermal Method in Vacuum

Xie Zhen, Zhou Dali, Yang Weizhong, Zhou Jiabei, Liu Can, Su Hua

2017, 38(1): 38-42. doi: 10.7513/j.issn.1004-7638.2017.01.007

Abstract(32) PDF(2)

Abstract:
Nano-titanium carbide （TiC） was prepared by in-situ carbothermal reduction under vacuum condition using the precursor synthesized by sol-gel method with tetrabutyl titanate（Ti（C₄H₉O）₄） and sucrose as titanium and carbon sources,respectively. X-ray diffraction and scanning electron microscope were respectively employed to analyze the phase composition and morphology of the obtained samples,and the size of the TiC crystals was calculated by Scherrer formula from the XRD data. The results show that nano-TiC can be synthesized at 1 300 ℃ in vacuum,and the purity of TiC increases while the crystal size decreases with increase in carbon content. When the carbothermal reduction temperature increases from 1 300 ℃ to 1 500 ℃,the morphology of TiC changes from long bars with about 100 nm of size to sphere particles with 20~30 nm of diameter,but the phase content of TiO is increased unexpectedly.

Effect of Annealing on Microstructure and Tensile Property of Cast TG6 High-temperature Ti-based Alloy

Zhu Langping, Li Jianchong, Mo Xiaofei, Luo Qian, Nan Hai

2017, 38(1): 43-47. doi: 10.7513/j.issn.1004-7638.2017.01.008

Abstract(32) PDF(1)

Abstract:
The microstructure and mechanical properties of high temperature titanium alloy TG6 under different conditions such as cast state,hot isostatic pressing and annealing treatment were studied.The results shows that the microstructure of the as-cast alloy is coarse Widmanstaten with shrinkage porosity,and the resulting tensile strength is 871.3 MPa,while the elongation is only 0.8%.It is found out that shrinkage porosity acts as crack initiation source.The tensile strength and elongation increase to 871.3 MPa and 0.8% respectively after HIP.The banded and granular（TiZr）₆Si₃ silicide phase precipitate in β lathes after annealing at 750 ℃,and β lathes dissolve partially.The ductility at room temperature improves to more than 5% after annealing,with no significant change of tensile strength compared to that of HIP,and the tensile fracture surface indicates the characteristics of cleavage fracture.

Study on Performance of TiC Particle Reinforced Martensite Wear-resistant Steel

Liang Xiaokai, Sun Xinjun, Yong Qilong, Kang Shaoguang, Zhu Xiuguang, Wu Jianpeng

2017, 38(1): 48-53. doi: 10.7513/j.issn.1004-7638.2017.01.009

Abstract(21) PDF(1)

Abstract:
TiC particle reinforced martensite wear-resistant steels with a hardness of HB450 were fabricated by mold casting and continuous casting processes.The principal of precipitation of TiC in experimental steels was studied.The microstructures and mechanical and wear-resistant properties of obtained steel were analyzed and compared with that of traditional martensite wear-resistant steels.It is found out that a higher solidification rate of continuous casting resulted in finer micron-sized TiC precipitates.In addition,a larger deformation ratio resulted in a more homogeneous distribution of TiC particles. Uniformly distributed micron-sized TiC particles could passivate the tip of the grains and stop scratches,which improved the wear resistant property of steels significantly,and reduced the weight loss to 70% compared with the traditional martensite wear resistant steels.

Effects of Heat Treatment Temperature on the Microstructure and Properties of High Vanadium High Speed Steel

Han Huihui

2017, 38(1): 54-59. doi: 10.7513/j.issn.1004-7638.2017.01.010

Abstract(22) PDF(1)

Abstract:
The new-typed W6Mo5Cr4V8 In high vanadium high speed steel used for numerical control machine were heat treated at various temperatures to test and analyze the microstructure,impact property and wear resistance. The results show that with heat treatment temperature increasing from 1 050 ℃ to 1 150 ℃ the grain size of the steel first decreases then increases,and both the impact property and wear resistance of the steel first enhance then decline.M₂C carbide is decomposed when the heat treatment temperature is between 1 080 ℃ and 1 150 ℃. The optimized heat treatment temperature is 1 080 ℃. Compared with those of the steel heat treated at 1 150 ℃,the impact absorption energy and wear volume of the steel with heat treatment at 1 080 ℃ increases by 46% and decreases by 48%,respectively.

Effect of La₂O₃ Doping on SCR Performance of V₂O₅-WO₃/TiO₂ Catalyst

Zhao Mengmeng, Chen Mengyin, Li Shangxiang, Zhang Pengju, Zhao Hui, Tang Fushun, Ruan Le, Yang Hongbin

2017, 38(1): 60-68. doi: 10.7513/j.issn.1004-7638.2017.01.011

Abstract(6) PDF(1)

Abstract:
Lanthanum （La） component was doped on TiO₂ supporter by co-precipitation method,and vanadium （V）,tungsten （W） components were then doped on La₂O₃-TiO₂ composite by impregnation method to prepare V₂O₅-WO₃/La₂O₃-TiO₂ catalyst.The effect of La₂O₃ doping amount on the performance of selective catalytic reduction of NO with NH₃ for the obtained catalyst was investigated and various characterizations were employed to analyze the catalyst. Test results of XRD,NH₃-in situ DRIFTS,H₂-TPR,XPS and UV-vis DRS indicate that La is combined with Ti by La-O-Ti bonds,forming highly dispersed LaO_x species which makes TiO₂ more thermally stable.However,the redox properties and surface Brønsted acid sites of the catalyst are decreased,which further lowers the catalytic activity,due to the interactions among LaO_x,VO_x and WO_x.

Effect of Vanadium on the Magnetic Properties of Oriented Electric Steel

Dong Huimin, Zhou Junping

2017, 38(1): 69-73. doi: 10.7513/j.issn.1004-7638.2017.01.012

Abstract(15) PDF(1)

Abstract:
The effect of vanadium on the magnetic properties of oriented electric steel was studied by testing and analyzing the iron loss P₁₇ and magnetic induction B₈ of the samples,with adding different content of vanadium in oriented electric steels.The results show that the average grain size and the iron loss P₁₇ of the oriented electric steel first decrease then increase while the texture grade and magnetic induction B₈ of the steel first increase then decrease with the magnetic properties of the steel improved first then declined,when the content of vanadium increases from 0.000% to 0.022%.The magnetic properties of the oriented electric steel will be deteriorated with more than 0.020% of vanadium content.The content of vanadium was optimized at 0.008%,and the average grain size and the iron loss P₁₇ of the steel respectively decreased by 14.29% and 15.32% while the texture grade and magnetic induction B₈ of the steel separately increased by 267.15% and 13.09%,comparing with those of vanadium-absence steel.

Study on Crystallization Behavior in Fibrosis Process of Molten Blast Furnace Slag

Ren Qianqian, Zhang Yuzhu, Long Yue, Chen Shaosheng, Zou Zongshu, Zhang Chunxia

2017, 38(1): 74-77. doi: 10.7513/j.issn.1004-7638.2017.01.013

Abstract(18) PDF(1)

Abstract:
The blast furnace slag was studied using Fact-sage thermodynamic software to simulate the precipitation temperature,species and contents of the minerals precipitated in the cooling process of molten blast furnace slag.The viscosity curves of blast furnace slag during cooling process were obtained by synthetic test instrument for physical characteristics of melt.Mineral compositions and microstructure of the blast furnace slag at different temperatures were analyzed by X-ray diffraction （XRD） and field emission scanning electron microscope （SEM）.The results indicate that the blast furnace slag begins to separate out crystals at 1 350 ℃ and the main crystal phase is composed of gehlenite（Ca₂Al₂SiO₇） and akermanite （Ca₂MgSi₂O₇）.In addition,the suitable temperature range for fibrosis of molten blast furnace slag is 1 350~1 371 ℃.

Effect of Acidity Coefficient on Crystallization of Molten Slag and Fiber Properties

Chen Shaosheng, Zhang Yuzhu, Long Yue, Ren Qianqian, Du Peipei

2017, 38(1): 78-82. doi: 10.7513/j.issn.1004-7638.2017.01.014

Abstract(16) PDF(1)

Abstract:
With blast furnace slag as raw material,the slag fibers were directly prepared by centrifugation process.The crystal content of the slag and properties of the formed slag fibers including the diameter,shot content and moisture with different acidity coefficients （M_k） for the slag,were determined at the same fibrosis temperature.The relationships between M_k and crystal content,the characteristics of slag fibers were established and the influence factors for the quality of slag fibers were also summarized in this paper.The results show that the crystals are mainly composed of calcium akermanite and gehlenite,and with increase in M_k the crystal content of slag gradually decreases,corresponding to changes in fiber properties.The shot content is inhibited by acidity coefficient,and a generally promotive effect on the diameter and moisture content of the slag fibers can be rendered by the crystals.A better fiber quality can be obtained with the value of M_k near 1.3.

Researches on Re-concentration of a Specularite Tailing from JISCO

Zhuang Jun, Chen Tiejun, Zhan Renli, Chen Sisi

2017, 38(1): 83-90. doi: 10.7513/j.issn.1004-7638.2017.01.015

Abstract(7) PDF(1)

Abstract:
The tailings from the dressing plant of JISCO contains about 25% iron,which has a high recovery value.Iron mainly exists in form of Hem-limoniteOre,and some of them in siderite and magnetite in this tailings.In this paper,the process of magnetizing roast-low intensity magnetic separation and high intensity magnetic separation-magnetizing roast-low intensity magnetic separation were investigated with semi coke as the reductant in order to recover the iron lost in the tailings.The experimental results indicate that the iron concentrate with iron grade of 54.50% and recovery of 86.26% has been obtained without pretreatment of the high intensity magnetic separation,which are close to the field data.Meanwhile,the iron concentrate with iron grade of 53.96% and recovery of 80.22% has been achieved when the high intensity magnetic separation is used.Though the iron grade and recovery rate have a little descent,this new process can help to significantly reduce processing volume and energy loss.

Exploration of Preparation and Dezincification Percentage of Metallic Pellets from Sintering Electric Remove Dust

Xie Jianbo, Zhou Jian'an, Wang Yayu, Ding Bin

2017, 38(1): 91-94. doi: 10.7513/j.issn.1004-7638.2017.01.016

Abstract(13) PDF(1)

Abstract:
In order to reduce the waste of sintering resources,sintering electric removal dust is explored to make metallic pellets with better metallurgical performances by adding certain appropriations of mill scale,activated carbon,bentonite and organic binder.Compressive strength and the dezincification percentage of the pellets of each group were examined after the raw pellets were preheated and baked.It is found out that compressive strength first increases and then decreases with increasing carbon amount into pellets.When the carbon content is 1%~4%,the dezincification percentage of the pellets keeps constant （47%）,but the dezincification percentage decreases at 5% carbon content. With 3% addition of activated carbon into sintering electric removal dust,i metallic pellets can be obtained with better metallurgical performances and low Zn content.

Influence of TiO₂ Content on Gathering of Iron in Titania Bearing Blast Furnace Slag

Lü Qing, Tian Ye, Liu Xiaojie, Chen Shujun, Sun Yanqin

2017, 38(1): 95-99. doi: 10.7513/j.issn.1004-7638.2017.01.017

Abstract(13) PDF(1)

Abstract:
The viscosity of vanadium titano-magnetite slag from Chengde iron ＆ steel company is greater than the common slag,the separation of the slag-iron is difficult and the iron content in slag is about 2%,all of which make the usage of slag difficult and production cost higher.This study had been done to figure out the existence form of iron in slag,the influence of TiO₂ content on iron gathering as well as the gathering mechanism of iron.The results show that with of TiO₂ content increasing,the quantity of gathering iron decreases,and the location of gathering iron changes from bottom and side to side and top,meanwhile there are high melting point Ti（C,N） particle appearing at the slag and the graphite crucible interface.With the content of TiO₂ increasing,iron content in slag increases from 0.4% to 1%.

Experimental Study on Coal Gasification of Gas-injection BF Process

Zhu Ertao, Li Fumin, Lu Jianguang, Lü Qing

2017, 38(1): 100-105. doi: 10.7513/j.issn.1004-7638.2017.01.018

Abstract(7) PDF(1)

Abstract:
The gas-injection BF process was proposed in order to overcome the adverse effects of pulverized coal injection,where the reducing gas produced by normal coal in a gasifier is injected to BF from tuyeres.The influence of process parameters on gas quality was determined. The results show that CO+H₂ content and calorific value of gas first increases and then decreases with gasification agent flow increasing,while steadily increases as the reaction temperature,material thickness,oxygen enrichment rate increase.When gasifying agent flow rate is 1.0 m³/h,the reaction temperature is 1 000 ℃,the material layer thickness is 1 000 mm,oxygen enrichment rate is 15%,the best gas quality can be achieved where CO + H₂ content reaches at 79.37% and LHV of gas reaches at 10 229.51 kJ/m³.

Influence of CaF₂ Content in the Continuous Casting Mold Flux on the Devitrification Properties

Wang Xingjuan, Fan Yapeng, Zhu Liguang, Wang Lijie, Wu Binbin, Tian Kuo

2017, 38(1): 106-112. doi: 10.7513/j.issn.1004-7638.2017.01.019

Abstract(19) PDF(1)

Abstract:
TTT curve was constructed using SHTT II melting and crystallization temperature measuring instrument,then the mold flux devitrification activation energy was calculated at different levels of CaF₂.To calculate the rate of crystallization and analysis crystalline phase,X-ray diddractometer combining with the JADE software are utilized.Various surface morphology of slag film protection with different CaF₂ content under the different temperature treatment was observed under the metallographic microscope,exploring the impact of CaF₂ on the devitrification of slag.It is found out that the temperature and activation energy of initial devitrified phenomenon decreases and the roughness on the surface of flux film increases with the CaF₂ content increasing.The mineral species tend to be single with treating temperature of glassy flux film increasing.

Inclusions Movement Behavior in Tundish after Ladle Changing

Pan Hongwei, Wang Leichuan, Guan Shunkuan, Ji Chenxi, Zeng Zhi, Cheng Shusen

2017, 38(1): 113-117. doi: 10.7513/j.issn.1004-7638.2017.01.020

Abstract(14) PDF(2)

Abstract:
With numerical simulation and industrial experiments,inclusions movement behavior in tundish under non-isothermal condition had been analyzed. Numerical simulation indicates that inclusions with different sizes tend to separate after ladle changing during continuous casting process,and inclusions with size lower than 50 μm are getting difficult to remove. During the middle and later period of casting process,inclusions with size lower than 50 μm tend to move along tundish bottom,and inclusions removing condition further worsens. Industrial experiments results show that by means of argon-blowing at tundish bottom,inclusions removing condition is improved. Average T.[O] content in tundish is reduced by 3.5 ppm,and nitrogen content is reduced by 3ppm.Before argon-blowing,inclusions quantity density of slab is about 0.008 8/mm², and reduced to 0.002 5/mm².after argon-blowing.

Comparision Experiments of Slagging and Desulfurization between the New Slagging Agent and Fluorite

Peng Qichun, Li Hailing

2017, 38(1): 118-122. doi: 10.7513/j.issn.1004-7638.2017.01.021

Abstract(13) PDF(1)

Abstract:
In order to understand the metallurgical effect of industrial by-product AF3F^TM which can be as the substitute of fluorite in steelmaking process,slag melting characteristics test,hot metal desulphurization and molten steel desulfurization experiments had been done to compare the slagging and desulfurization effect between this AF3F^TM and fluorite slagging agents.Through those experiments it can be concluded that AF3F^TM has better metallurgical effect than fluorite ball and can reduce the lime melting point to lower level. When the ratio of this two slagging agents is 10%,the melting point of lime with AF3F^TM is reduced by 45 ℃.The slag which contains AF3F^TM can achieve slag formation faster and has better desulfurization result.Under the same experiment conditions,AF3F^TM can save at least 20% in terms of usage,and resulted the fluoride waste emissions is reduced by 10% compared with fluorite ball. Therefore,this new slagging agent can find its valuable application in the metallurgical industry,analyzed comprehensively from the perspectives of resources,cost,environmental and metallurgical effect.

Effect of CaF₂-MgF₂ on the Removal of Al₂O₃ Inclusions in Steel

Peng Chengsong, Zhou Defu, Wang Jianjun, Chang Lizhong, Wang Kaizhong, Sun Wei

2017, 38(1): 123-131. doi: 10.7513/j.issn.1004-7638.2017.01.022

Abstract(16) PDF(1)

Abstract:
Different amounts of CaF₂,MgF₂,Na₃AlF₆,mixture of CaF₂ and Mg F₂ were added into the liquid steel for Al₂O₃ inclusions modification. The results show that total oxygen content of the treated steel obviously decreases,but the amount of addition needed shall be in a suitable range. adding 1.0% of mixture of CaF₂ and MgF₂ can achieve the best modification result. In addition,the inclusions in the steel treated by the modified agent present a composite layer shape of Mn S wrapped Al₂O₃,which is more beneficial to the removal of inclusions,and Mn S is a plastic inclusion,which can reduce the negative effect of Al₂O₃ inclusions in steel.

Experiment Research on Hydrogen Reduction at Fluidized Bed of Bayan Ebo Iron Concentrate Powder

Pei Xiaoyu, Zhao Wenguang, Zhao Tuan, Peng Jun, An Shengli

2017, 38(1): 132-137,147. doi: 10.7513/j.issn.1004-7638.2017.01.023

Abstract(13) PDF(1)

Abstract:
The influence of different temperature and hydrogen flow rate on reduction of Bayan Ebo iron concentrate powder was studied by a visible fluid bed.The results show that increasing hydrogen flow rate helps to improve the reduction efficiency at the same temperature.However,this effect becomes apparent at low temperatures.The influence of temperature has the same tendency as hydrogen flow rate. The kinetics of hydrogen reduction of Bayan Ebo iron concentrate powder was studied by thermo-gravimetric analysis under different temperatures.It indicates that the restrictive factor to is gas phase diffusion. The activation energy first decreases and then increases with the reduction time,and decreasing of the apparent activation energy is more favorable to the acceleration of the reaction. Under the experiment conditions 5~10 mins reaction time can achieve the bigger reduction reaction rate.

Production Process and Properties of DP800 Dual Phase Steel

Qing Jiasheng, Shen Houfa

2017, 38(1): 138-142. doi: 10.7513/j.issn.1004-7638.2017.01.024

Abstract(12) PDF(1)

Abstract:
The composition system,cooling treatment process,microstructure and performance of 800 MPa dual phase steel have been studied,and the effects of annealing temperature and cooling rate on the properties have been investigated.The strengthening mechanism of dual phase steel was analyzed,and the annealing process parameters were optimized. Results show that smelting process using C-Si-Mn-Cr-V component system,rolling process using 650 ℃ ± 20 ℃ in the temperature coiling,microstructure and mechanical properties can be qualified with cooling rate of 42~50 ℃/s and high content hydrogen H₂ of 20%,and cold-rolled dual-phase steels DP800 composed of ferrite and martensite can be obtained,and the comprehensive mechanical properties are excellent.

In-situ Observation of Acicular Ferrite in High Strength Ship-building Plate Steel

Gao Lina, Zhang Caijun, Gu Kejing, Zhu Liguang

2017, 38(1): 143-147. doi: 10.7513/j.issn.1004-7638.2017.01.025

Abstract(15) PDF(1)

Abstract:
The acicular ferrite in high strength ship plate steel was observed by confocal scanning laser microscope （CSLM）,and morphology in steel of in situ observation was investigated by using optical microscopy.The results show that holding time of 900 s is in favor of acicular ferrite nucleation.The austenite grain size increases with increasing holding time.The austenite size that is acquired at 900 s of the holding time is more conducive to the nucleation of acicular ferrite. The starting formation temperature of ferrite firstly decreases with increasing holding time,then increases. The ending formation temperature of ferrite decreases with increasing holding time.

Effect of Annealing Processes on Microstructure and Recrystallization Texture of a Cold-rolled High Strength IF Steel

Jin Juan, Wu Run, Tang Mengxia, Fan Lixia, Zhou Herong

2017, 38(1): 148-152,162. doi: 10.7513/j.issn.1004-7638.2017.01.026

Abstract(15) PDF(2)

Abstract:
A cold-rolled high strength IF steel was annealed at two different heating rate to study the evolution of microstructure and recrystallization texture of IF steels. The results show that the γ-fier（{111} or（ND‖＜111＞）） of IF steel form at both of two recrystallization annealing processes.When the samples are heated at fast rate of 350 ℃/min,the recrystallization grains grow from the merging of subgrains and show equiaxed morphology.The orientation of recrystallization grains was consistent with the surrounding deformation matrix.When the samples are heated at slow rate of 2 ℃/min,the new grains grow from grain boundary bowing,showing pancake grains along the rolling direction with weak orientation to the deformed grains.The density of γ-{111} orientation of the samples with slow heating rate are stronger than that with fast heating rate.The results are of great significance to improve the deep drawability of the thin sheet.

Thermodynamics Analysis and Control of Inclusion in 82B Hard Wire Steel

Dong Tingliang, Xiao Guohua, Gao Yu, Zhang Shouwei, Li Bobin, Xu Bin

2017, 38(1): 153-156. doi: 10.7513/j.issn.1004-7638.2017.01.027

Abstract(20) PDF(2)

Abstract:
The formation conditions of inclusion in 82 B hard wire steel was predicted by the thermodynamics calculation. The calculation results indicate that when low basicity slag is used,the content of[Al]_S in the molten steel increases with the increasing of w_CaO/w_SiO₂ ration and the content of Al₂O₃ in inclusion.The content of [Al]_S in the molten steel should be less than 6×10^-6 in order to control CaO-SiO₂-Al₂O₃ inclusion in plastic zone.Practical control result indicates that controlling refining slag composition （controlling the content of Al₂O₃ in the top slag less than 10%） which is selected based on result of thermodynamics calculation,while ensuring adequate soft blowing conditions （suitable argon flowing and more than 15 min soft blowing time）,controlling inclusion can be achieved.

Analysis and Research for Surface Sliver Defect of Steel Plate

Wu Xiaoyan, Zhu Liguang, Mei Guohong, Yan Chunliang, Cao Shengli, Zhang Qingjun

2017, 38(1): 157-162. doi: 10.7513/j.issn.1004-7638.2017.01.028

Abstract(36) PDF(1)

Abstract:
Scanning electron microscopy along with energy dispersive spectroscopy and optical metallographic microscope were employed to analyze the cause of formation of sliver defects on the surface of steel plate.The results show that the main reasons for the sliver defect of steel plate surface are the scratch,inclusion and crack of the slab.A thin layer of high temperature oxidation,a large number of small high temperature oxidation dots and signs of decarburization can be observed at the defects caused by Casting slab crack and scratch,while Na and K elements can be detected in the linear defect caused by inclusion.In order to reduce the linear defect on the surface of the steel plate,the author puts forward the corresponding improvement measures for the relevant reasons,which has certain reference for the practical production.

2017, 38(1): 163-164.

Abstract(24) PDF(1)

Abstract:

2017 Vol. 38, No. 1