钢铁钒钛

Development and Problems of the Titanium Sponge Production Technology in China

Deng Guozhu

2011, 32(4): 1-5.

Abstract(27) PDF(1)

Abstract:
The rapid development of China's titanium sponge production,including capacity and technological progress(the international mainstream technologies have been applied in the main processes),are described in the paper.The problems of China's titanium sponge industry,such as overcapacity,shortage of titanium mineral feedstocks,and incomplete cycling of chlorine and magnesium are analyzed.The ways to solve the problems in China's titanium sponge industry are pointed out,including forming a complete set of advanced technologies and equipments,consistent supply of raw materials and stable marketing channels or self-possessed titanium material processing systems,so as to make full use of titanium sponge production capacity in China.

Preparation of Porous Titania Photo-catalyst from Industrial Titanyl Sulfate Solution via Hydrothermal Synthesis

Pu Hong, Tian Congxue, Yang Ying, An Yun

2011, 32(4): 6-11.

Abstract(31) PDF(1)

Abstract:
Porous TiO₂ photo-catalyst is prepared via hydrothermal synthesis route from industrial titanyl sulfate solution,and the effects of calcination time on the structure and property of porous TiO₂ are also investigated.The as-prepared samples are characterized by XRD,SEM,XPS,FT-IR and BET,and their photocatalytic activities are evaluated by photocatalytic degredation of methylene blue.As the increase of calcination time,the photocatalytic degradation rate increases at first and then gradually decreases.Porous titania calcined at 500℃ for 1 h shows a lowest photocatalytic activity,with a degradation rate of 88%,SBET of 61.49 m²/g and crystal size of 16.10 nm.

Research on Low-temperature Chlorination Process of Pangang Carbonized Slag

Huang Jiaxu, Yang Yangjun, Lu Ping, Liu Senlin

2011, 32(4): 12-15,50.

Abstract(21) PDF(3)

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The low-temperature chlorination process of the Pangang carbonized slag is researched;and the effect of different chlorination temperatures,residence time,air velocity and chlorine concentration under continuous feeding and continuous slagging on the TiC chlorination rate is studied through the self-designed Ø100 mm continuous fluidizing chlorination equipment.As a result,favorable process parameters are obtained,which paves the way for further enlarged experiments.

Continuous Cooling Transformation of a Kind of Nb-Ti Microalloyed Steel

Zhang Xi, Li Deqiang

2011, 32(4): 16-21.

Abstract(22) PDF(1)

Abstract:
Continuous cooling transformation(CCT) tests at different deformation condition are carried out on the MMS-200 thermal simulator.Phase transition temperature of the tested steels at different cooling rates are determined through thermal expansion method combined with metallographic method.The percentage content of pearlite is defined and microstructure of test steel is observed in utilization of optical microscope and scanning electron microscopy(SEM).Continuous cooling transformation(CCT) curve of the tested steel under deforming and non-deforming condition is drawn afterwards,and finally the effect of different deformation process on continuous cooling transformation behavior and microstructure of microalloyed steel is concluded.

Influence of Ti/N Ratio on Microstructure and Mechanical Properties of High Strength Bainitic Steel Plate

Zhang Tao, Hou Huaxing, Chen Junping, Wang Xiaoqiang, Liu Ming

2011, 32(4): 22-25.

Abstract(31) PDF(1)

Abstract:
The effect of Ti/N ratio on microstructure and mechanical properties of high strength low-carbon bainitic steel plate is investigated.The result shows Ti/N ratio have obvious effect on the yield of acid-soluble boron in steel and mechanical properties of that kind of steel.Boron yield of no more than 50% could be obtained when the Ti/N ratio is below 3.3,more than 75% obtained when the ratio over 3.6,and nearly 90% obtained when the ratio reaches 4.The mechanical properties of the steel are obviously improved with the increase of the Ti/N ratio.Adding enough Ti to boost Ti/N ratio is an effective and economic way to increase effective boron yield and further improve the mechanical properties.

Research on Microstructure and Property of V-alloyed Superbainite Steel

Xu Guang, Yang Jing, Zou Hang, Bu Conghua, Cao Longfei

2011, 32(4): 26-30.

Abstract(25) PDF(1)

Abstract:
A new bainite steel with low carbon and low alloy additions is designed and refined in laboratory.The phase transformation test at air cooling condition is carried out on Gleebe-1500 thermal simulator.Bainite transformation range is decided according to the dilation curve and microstructure.Then isothermal processing tests are performed at different temperatures and resulting microstructures are observed.According to the isothermical processing test results the samples are treated by isothermal heat treatment at 320℃ for different time.The following tensile tests indicate that the steel has a good comprehensive property with the ultimate strength of 1 182 MPa and total elongation of 19.0%.The research results demonstrate that bainite microstructure and good strength and toughness can be obtained through short-time bainite transformation.

Experimental Research on Production of Low-sulfur Iron Nuggets with Iron Concentrate Powder and Pulverized Coal

Ma Sai, Wang Jingsong, Ding Yingui, Wang Guang, Xue Qingguo

2011, 32(4): 31-35.

Abstract(35) PDF(1)

Abstract:
According to different experimental plans,reduction experiments of carbon-bearing pellets mainly composed of iron concentrate,pulverized coal,limestone and CaF₂ are carried out to analyze the production process of iron nuggets,chemical compositions and microstructure of slag and calculate the distribution of sulfur.The results show that:with reasonable experiment plans,we can get a good effect during the process of reduction,melting and separation of carbon-bearing pellet and finally iron nuggets with low sulfur in 27 min;the internal microstructure of iron nuggets principally consists of pearlite and cementite;major chemical compositions of the slag are Ca₂Mg(Si₂O₇) and Ca₃Mg(SiO₄)₂,with a very small amount of other compositions;increasing the amount of CaF₂ added decreases sulfur in iron nuggets while increases it in slag;increasing heating temperature decreases sulfur in iron nuggets while increases it in the air.

Numerical Studies on Metallurgical Behavior of Liquid Steel in Slab Mold with Electromagnetic Brake

Ni Shengqi, Peng Shiheng

2011, 32(4): 36-41.

Abstract(22) PDF(1)

Abstract:
The numerical simulation study on metallurgical behavior of liquid steel in the slab mold with and without electromagnetic brake is carried out.The numerical simulation results show that in the presence of EMBR,the velocity of liquid steel in the slab mold is reduced largely with the highest velocity of meniscus reducing from 0.17 m/s to 0.02 m/s.The temperature of liquid steel in some part of casting blank gets higher,with a lower temperature of solidification shell.The shell gets thicker at narrow sides and the corner while gets thinner at wide sides.

Optimization of CAS Process by Physical Model Study

Shu Zhihao, Chen Yuanqing, Yan Huicheng, Chou Shengtao

2011, 32(4): 42-45.

Abstract(31) PDF(1)

Abstract:
In order to optimize the process of a 230 t CAS ladle,a physical model has been built with a scale factor of 1:4.Location of bottom lowing,gas flow rate and depth of the snorkel have been optimized by mixing time test,and the appropriate gas flow rate for deslagging has been determined in deslagging experiment.The results show that position of plugs for better mixing can be seen in scheme 8(plug 1 and 2 are 600 mm and 1 000 mm from the center of ladle bottom respectively and the intersection angel between these two plugs is 100°);the optimum gas flow rate for mixing should be 600~700 NL/min;the depth of snorkel is about 200 mm for better mixing.Where the thickness of slag layer is 80,120,160 mm,the gas flow rate for deslagging should be more than 600,800,1 000 NL/min respectively.

Physical Modeling Study on the Meniscus Flow Control in Vertical Slab Continuous Casting Mold

Zhao Zhigang, Chen Yuanqing, Shi Zhe, Hu Kuntai, Chou Shengtao

2011, 32(4): 46-50.

Abstract(23) PDF(1)

Abstract:
In order to study the influence of mold flow control device(MFCD) on mold flow field at low casting speed,a full scale water model has been set up to simulate the mold flow field of vertical slab continuous caster in Baosteel.With two types of submerged entry nozzle(SEN),the effect of equipping MFCD or not,the position and the immersion depth of MFCD on mold level fluctuation and mold field distribution has been studied.The results show that MFCD has no obvious effect on the mold flow field distribution,but decreases the mold level fluctuation with downward outlet SEN.However,with upward outlet SEN,MFCD has obvious effect on the mold flow field distribution and largely increases the mold level fluctuation at some point of free surface.To the extent of immersion depth from 50 mm to 100 mm,the influence of MFCD position is more significant than MFCD immersion depth on mold level fluctuation.The MFCD is not applicable for slab continuous casting at low casting speed.

Effect of Unsteady Casting of Non-oriented Electric Steel Slab on the Iron Loss of Final Steel Sheets

Zhang Feng, Li Guangqiang, Ma Zhangsong, Chen Xiao

2011, 32(4): 51-57.

Abstract(15) PDF(1)

Abstract:
The amount,composition and size of inclusions in finished specimens of steady and unsteady casted non-oriented electric steel slabs are analyzed by electrolysis extraction of inclusions and SEM-EDS and the effect of inclusions on iron loss of coil is discussed.The results show that the main inclusions are AlN,MnS and Cu₂S in both of these slabs with a small amount of inclusions in the first and final slabs.The amount of inclusions under 0.5 μm is about 15,000,000 per cubic millimeter and the amounts of inclusions with size range between 0.5 μm and 5.0 μm are 1,230,000 per cubic milimeter and 750,000 per cubic milimeter in unsteady and steady casted non-oriented electric steel slabs respectively.This is the main reason for the different iron loss between these corresponding finished products under steady and unsteady casting processes with the same casting heat.

Study on the Reduction Swellability of Panzhihua V-Ti bearing magnetite Concentrate Pellets

Ma Lan, Yang Shaoli

2011, 32(4): 58-62.

Abstract(28) PDF(1)

Abstract:
The effect of the binder content and the calcination atmosphere on the reduction swellability of the pellets is monitored by the on-line pellet morphology detector.The research results show that by adding a small amount of binder(the bentonite content is less than 1.5%) to the Panzhihua V-Ti bearing magnetite concentrate,the resulting pellets could meet the requirements of the blast furnace after magnetizing roasting in temperature of 1 100~1 200℃,with a maximum linear expansion rate of less than 5% during reduction.The pellets which are not pulverized contribute to the smooth operation of blast furnace.

Influence of Tempering on Microstructure and Mechanical Property of Si-Mn-Mo Bainite Steel

Yang Yu, Chen Xin, Du Zhenmin, Jin Jiyong

2011, 32(4): 63-66.

Abstract(23) PDF(1)

Abstract:
The influence of tempering at different temperature on microstructure and mechanical property of Si-Mn-Mo bainitic steel after quenching is studied in laboratory.It is found that strength and plasticity of this steel can be significantly improved through tempering after quenching.Mechanical properties of the bainitic steels tempered at 300℃ or 350℃after quenching are similar while the strength and hardness is reduced and toughness and plasticity is slightly improved after tempering at 450℃.The microstructure of the bainitic steel is composed of bainitic ferrite and residual austenite(flaky and blocky M-A island).Tempering properly after quenching can accelerate the decomposition of the M-A island,so percentage composition of the bainitic ferrite lath is increased and the stability of residual austenite can be improved.Thus,the stability of microstructure and mechanical property of this steel is improved.

Study on Thermal Simulation Experiment of CSP Hot Rolling of Fe-3%Si Steel

Ji Yunping, Jin Zili, Li Wei, Ren Huiping

2011, 32(4): 67-70.

Abstract(23) PDF(1)

Abstract:
The thermal simulation experiments of heating,hot rolling and coiling of Fe-3%Si steel are performed by simulating on site CSP process and environment.The recrystallization behavior of Fe-3%Si steel in the simulated CSP hot rolling process is studied by Gleeble-1500D thermal simulator.The results show that the process with the pass reduction of 45%-40%-40%-20%-35%-35% can obtain finer grains,so the dynamic recrystallization has accomplished better in this process.With the increase of coiling temperature,the average grain size becomes smaller.When the coiling temperature is 650℃,the grain size is relatively uniform.The results can provide an experimental basis for the study of thermal deformation behavior of grain-oriented silicon steel prepared by CSP process.

Research on Microstructure and Precipitates of Non-oriented Silicon Steel Sheets After Annealing for High-efficiency Motor

Li Yongchao, Li Na, Yue Erbin, Xiang Li, Zhang Yanling, Chou Shengtao

2011, 32(4): 71-75.

Abstract(33) PDF(1)

Abstract:
Effects of microstructure and precipitation on magnetic property of non-oriented silicon steel sheets after annealing for high-efficiency motor are studied in the paper by experiments.The annealed sheet exhibits a larger average grain size,obviously decreasing iron loss and slightly raising magnetic induction with increasing temperature.The annealed sheet has better comprehensive properties at a annealing temperature of 1 000℃.The main precipitates are compounds of AlN、(MnS+AlN)and(MnS+Al₂O₃) with coarse size of 1.0~2.5 μm.Besides,a few fine AlN and TiN with size below 100 nm are found.Iron loss of electrical steel simulated by TSCR process in laboratory is 4.00 W/kg and magnetic induction is more than 1.75 T.It is suitable for producing iron cores for small and medium sized high-efficiency motors.

Hot Plasticity of 610L Continuous Cast Slab for Automobile Beam

Sun Wei, Sun Jiquan, Zhao Zhengzhi, Zhao Wenlong, Bao Kuo

2011, 32(4): 76-81.

Abstract(18) PDF(1)

Abstract:
The high-temperature thermoplasticity experiment of 610L continuous cast slab for automobile beam is performed at Gleeble-3500 thermal simulator.The fracture appearance and microstructure is examined with SEM.Results indicate that there are two brittle zones at temperature range of 1 300~600℃ in which brittle zone Ⅲ is at about 910~705℃.The main causes for the low ductility in brittle zone Ⅲ are studied.The experiment provides a basis for the development of continuous casting and hot rolling process system of that steel type.

Study on Characteristics of Air-mist Jets of Secondary Cooling of Continuous Casting

Hua Qinian, Zhang Yazhu, Zhao Zengwu, Zhao Lifeng, Zhou Liping

2011, 32(4): 82-86.

Abstract(13) PDF(1)

Abstract:
A flow characteristic experiment for a nozzle used in a secondary cooling zone for continuous casting was carried out in a steelmaking plant to discuss the jet angle,water flow distribution and drop size etc.The experiment results contribute to further study on heat transfer mechanism,water spraying system and the optimal nozzle array arrangement for the secondary cooling.

Carbon Macrosegregation Heredity of Cast Bloom of Special Steel and Microstructure Characteristics of Its Rolled Bar

Xu Weiyang, Cao Zhigang, Yan Huicheng, Tang Guangbo, Chou Shengtao

2011, 32(4): 87-91.

Abstract(29) PDF(1)

Abstract:
We followed the production of 20CrMnTi and 42CrMo steel and took the samples of cast bloom and rolled bar at the same batch.By analyzing their macrostructure and carbon macrosegregation,we found the carbon segregation had definitely inherit characteristics from cast bloom to its rolled bar,which led to segregation with ingot shape in the rolled bar,and the macrostructure of rolled bar was related with solidification structure of cast bloom.We observed the segregation in the rolled bar under the optical microscope and found that the rolled bar had different macrostructure in and out of the ingot-shape area.We also found banded structure in the 20CrMnTi steel which was bad for homogeneity and finally influenced the quality of finished products.

Improvement of Key Production Processes of 20CrMnTi Gear Steel

Cao Zhigang, Du Zhongze, Xu Weiyang, Yan Huicheng, Yu Haiming

2011, 32(4): 92-96.

Abstract(19) PDF(1)

Abstract:
The process management during the transportation of molten steel for gear steel production from BOF to electric furnace shop for further refining in the No.2 plant of a steel and iron company is briefly discussed.The dephosphorus and slag stopping in BOF,and the electricity delivery and calcium disposal in LF,important procedures affecting product quality,are included in the paper.Meanwhile the rolling process is also improved,and the advanced TMCP technique of controlled rolling and controlled cooling(CRCC technology) is adopted.Thus,rolled products with more consistent quality are obtained.

2011, 32(4): 97-98.

Abstract(12) PDF(1)

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2011 Vol. 32, No. 4