钢铁钒钛

Research on the Cabothermic Reduction of Low-grade Titanium Concentrate by Microwave Heating

Lei Ying, Li Yu, Peng Jinhui, Zhang Libo, Zhang Shimin, Guo Shenghui

2010, 31(4): 1-6.

Abstract(18) PDF(1)

Abstract:
Cabothermic reduction of Panzhihua low-grade ilmenite by microwave heating was studied in this work.The effects of preoxidation,coke ratio,additives on Fe metallization of reduced titanium concentrate were investigated.The experiment results show that under the optimum conditions of preoxidation temperature 800℃ by conventional heating,proportioning ratio of Na₂B₄O₇ 3% and coke ratio 10%,reduction temperature range 1 000~1 100℃,reduction time 60 min,the Fe metallization of the reduced product exceeds 90%.The reinforce mechanisms of microwave during reduction of titanium concentrate were deduced as follow:the crackle and porosity distribute inside ilmenite pellets induced by thermal stress originated from microwave selective heating can promote the spread of reducing atmosphere,and the large number of iron nuclei caused by quickly reduction can accelerate the reduction of ferriferous oxide.

Ball Milling Activation and Microwave Reduction of Titanium Concentrate

Li Yu, Lei Ying, Peng Jinhui, Zhang Libo, Zhang Zebiao, Guo Shenghui

2010, 31(4): 7-11.

Abstract(22) PDF(1)

Abstract:
The ball milling and followed microwave reduction of Panzhihua low grade titanium concentrate were investigated.The grain size and phase transformation of ilmenite were characterized by LPS and XRD TG techniques under different ball milling conditions.The results show that the ore particle,ilmenite crystal grains were fined and characteristic crest widened after milled.The behavior of the rise of temperature and reduction of the activated mixed mineral were studied,and the morphology and phase component of reduction product was also analyzed.The results show that the activated mixed mineral owned a well microwave absorption property and reduction effect in the microwave field.Hotspots were verified during reduction process.A 90% Fe-metallization of activated ilmenite was obtained under the conditions of temperature 900℃ and holding time 30 min.

Experiment on Hydrogen Reduction of Titanium Concentrate

Si Zhenbing, Gu Wuan, Yuan Xizhi, Huang Dandan

2010, 31(4): 12-15,21.

Abstract(17) PDF(1)

Abstract:
With the increase of titanium demand,the research on the reasonable utilizaion of titanium concentrate shows an important meaning,especially the environmental friendly pyrometallurgical process for high titanium slag preparation becomes a hot spot.The reduction processes of titanium concentrate with hydrogen gas in the tubular-furnace are discussed.It indicates that it has better reaction effect for titanium concentrate under the temperature of 1 000℃,with particle size of -0.088 mm and reaction time up to 20 min.

Study on High Temperature Oxidation Behaviors of Titanium Alloy TC4 in Laboratory

Yang Xiongfei, Huang Deming, Wei Qingfeng, Zhao Tongxin

2010, 31(4): 16-21.

Abstract(17) PDF(1)

Abstract:
The oxidation behaviors of most widely used titanium alloy TC4 was investigated at four different atmosphere temperatures ranging from 850℃ to 1 050℃.The morphology of the oxidation and oxide-rich layer of TC4 was analyzed by OM and SEM.The results indicated that the oxidation layer weight addition per unit surface area of TC4 showed a nearly linear relation to exposed heating time.Oxidation skin of TC4 formed by oxidation at single α phase range of lower temperature 850℃ was completely different that at 950,1 000℃ and 1 050℃.The mean thickness of internal oxidation layer was found strongly depending on oxygen diffusion rate at certain heating temperature and independent of heating time.Moreover,vanadium was found readily being enriched within oxide-rich layer.

Trail on Vanadium Recovery of Low-vanadium Hot Metal

Dong Wanchun, Ge Wensun, Shi Zhe

2010, 31(4): 22-27.

Abstract(16) PDF(1)

Abstract:
Using the both converters link method that a converter is used for vanadium-recovering and another converter for steelmaking,industrial tests of low vanadium hot metal are carried out and vanadium slag of 143.2 t is obtained,according to site conditions of equipments and process and characteristics of low vanadium hot metal of Pangang Group Chengdu Iron and Steel Co.,Ltd..Various technical and economic parameters of vanadium recovery from low vanadium hot metal are good that [C] in semi-steel is 3.23%,[V] in semi-steel 0.036%,temperature of semi-steel 1 395.5℃;V₂O₅ content in vanadium slag is 6.71%,total Fe in it 34.2%;vanadium oxidation ratio is 76%,rate of vanadium recovery 62.78%.The oxidation features of carbon and vanadium in vanadium recovery process show that vanadium recovery mainly started at 3 min before oxygen blowing and ended at 4.5 min of oxygen blowing process,and carbon oxidation is mainly carried out in the later period of vanadium recovery.

Microalloying Study on HRB400 Hot Rolled Ribbed Reinforced Bar

Tang Haiyan, Li Jingshe, Yang Mingsheng, Zhang Yabin, Zheng Quanzheng

2010, 31(4): 28-32.

Abstract(16) PDF(1)

Abstract:
To improve comprehensive mechanical properties of hot-rolled ribbed reinforced bar HRB400,the effects of increasing nitrogen of nitride alloys Si₃N₄,VN and MnSiN were tested respectively.Microalloying research was carried out by the combination of nitride alloys and FeV,FeNb and FeTi.The yield strength,tensile strength and elongation of bar were used as the evaluation index of mechanical properties.The results show that the effect of increasing nitrogen of MnSiN is the most obvious,and its use can reduce the consumption of alloys FeV and FeNb,further reduce production costs.When producing HRB400 with MnSiN and FeV microalloying,5 kg of MnSiN alloy and 0.50 kg of FeV for one ton of steel are appropriate ratios.

Control of Stamping Properties of St37-2G Cold Rolled Steel Sheet

Duan Xiangdong

2010, 31(4): 33-38.

Abstract(11) PDF(1)

Abstract:
According to the characteristics of cover annealing process,effects of chemical compositions,cold rolled reduction and annealing process on the microstructure and properteis of the St37-2G coldrolled steel sheet were investigated sysmatically.The controlling method of the plastic strain ratio of the steel was discussed and a technical plan to produce St37-2G coldrolled steel sheet with weighted average value of high plastic strain ratio(r_m) was put forward.The industrially-produced St37-2G coldrolled steel sheet exhibited excellent stamping properties.

Analysis of the Formation of Cold Rolled Defects in Ti-IF Steel

Wu Weishuang, Liu Jianhua, Wang Min, Cui Heng, Bao Yanping

2010, 31(4): 39-45.

Abstract(17) PDF(1)

Abstract:
The surface defects of cold rolled Ti-IF steel sheet was studied.According to the analysis of morphology of defect area and inclusions compositions with SEM/EDS,a lot of alumina,aluminosilicate,silica and magnesia-alumina spinel in defect parts were found.Besides,the rolling simulation test of the sample from first-slab which has more inclusions was carried out.The results of the test further confirmed the presence of these kinds of inclusions mainly cause the surface defects of the cold rolled sheet of Ti-IF steel.

Experimental Study of Dual-Phase Type Hot-rolling Automobile Structure Steel

Wang Wei, Gu Hairong

2010, 31(4): 46-50.

Abstract(22) PDF(1)

Abstract:
The relationships of process and microstructure and properties of hot rolled dual-phase steel(DP600) were investigated by laboratory rolling and simulation of coiling.The result showed that this DP steel with C-Si-Mn-Cr was provided with ferrite and martensite,and possessed excellent properties by using two-stage cooling and low-temperature coiling.It can be seen from the results that the volume fraction of ferrite of this experimental steel was mainly affected by the beginning temperature of water cooling better than time of air cooling.At the same time,the results of tempering experiments showed that martensite of this steel was stable only under 175℃.

Research on Hot Ductility of Common Grain Oriented Silicon Steel

Hou Zewang, Zhang Chen, Xiang Li, Chou Shengtao

2010, 31(4): 51-55.

Abstract(18) PDF(1)

Abstract:
High temperature mechanical property tests of common grain oriented silicon steels produced by thin slab casting and rolling route(TSCR) in laboratory have been carried out.The influence of dynamic recrystallization,precipitates and phase transformation on hot ductility of grain oriented silicon steel is analyzed.The results show that the brittleness region Ⅱ does not appear in grain oriented silicon steel examined.The temperature range of ductility region Ⅲ is about 850~6 00℃.Precipitates along the grain boundaries and phase transformation mainly lead to a decrease on hot ductility of grain oriented silicon steel.

Analysis on Causes of Corner Transverse Cracks Formation for Q345B Slab

Li Juyan, Wen Guanghua, Tang Ping, Guo Qiushi

2010, 31(4): 56-61.

Abstract(19) PDF(1)

Abstract:
Features and causes of corner transverse cracks for Q345B slab were analyzed based on metallographic microscopy,scanning electron microscopy and energy dispersion scanner.The results shows that the causes of forming cracks are the chain-like manganese sulfide compound and the film-like proeutectoid ferrite precipitated surrounding the austenite grain boundaries.The fine MnS precipitated along the austenite grains boundaries during slab solidification,then further accelerated the formation of thin films proeutectoid ferrite when the temperature of the slab surface droped to the austenite-ferrite transformation temperature range.When the slab was subject to straightening stress,all the strain mainly concentrates in these thin films,encouraging the formation of micropore around the MnS boundaries and these micropore polymerization gradually results in the formation of the crakes.

Analysis of Cleanliness of P12 High-pressure Boiler Steel

Yang Yan, Liu Jianhua, Bao Yanping, Zhao Peng, Hu Jiancheng

2010, 31(4): 62-66,79.

Abstract(17) PDF(1)

Abstract:
The cleanliness of P12 steel produced with EAF-LF-VD-MC process was studied systematically by sampling in various process stages in the production and with multiple analyzing techniques investigating the shape,size,quantity and component of inclusions.The results indicate that,in the refining process,T[O] and microinclusions in steel reduce 51.2 percents and 50.8 percents respectively.After VD treatment,average nitrogen increase rate of molten steel is 54.2 percents right to forging ingot and secondary oxidation of molten steel is rather noticeable.The average amount of oxygen,microinclusions and large inclusions are 20×10^-6,6.19 per square millimeter and 0.35mg/kg respectively,reaching rather high levels.

Numerical Simulation of Electromagnetic Stirring in Bloom Continuous Casting Mold

Wei Ning, Bao Yanping, Wu Huajie, Wang Guoxin, Liu Jinjin

2010, 31(4): 67-72,85.

Abstract(15) PDF(1)

Abstract:
According to Maxwell electromagnetic field theory,the electromagnetic field during the mold electromagnetic stirring for 240 mm×280 mm bloom casting was simulated by means of ANSYS software.The effects of the current intensity,frequency,and mold copper on magnetic field distribution in the electromagnetic stirrer were analyzed and the relationship between the characteristics of the magnetic field and parameters of electromagnetic stirring was obtained.Resultsshow that the rotary magnetic field can generate rotary electromagnetic force in mold to make molten steel whirling at horizontal section.The magnetic induction density increases linearly with the current intensity increase,the effect of frequency on electromagnetic stirring intensity is slight when the frequency is low,while the thickness of the mold copper has a great impact on the electromagnetic stirring intensity.The simulation results are consistent with the measured ones.

Numerical Simulation and Trial of the Fluid Flow in a Six-strand Tundish for Billet and Round Billet Caster

Huang Guangdong, Wen Guanghua, Tang Ping, Zhu Mingmei, Li Jianquan, Zhu Yicai

2010, 31(4): 73-79.

Abstract(15) PDF(1)

Abstract:
Based on the numerical simulation,fluid flow and heat transfer of molten-steel in a curved shape six-strand tundish for the billet and roud billet caster under different conditions(bare tundish and tundish with flow control device) were analyzed.The results showed that the tundish with flow control device which make up of "V" type baffle with holes,turbulence inhibitor and dam more effectively reduce the wall shear stress on the curved wall,optimize tundish flow field,uniform temperature distribution of molten steel and promote nonmetallic inclusions removed.The investigation results of the adoption of flow control device on the six-strand tundish showed that tundish temperature difference between adjacent stream is less than 5 K,the maximum of average temperature difference is 2.7K;average T[O] of 37Mn2 is 17×10^-6;the size of oxide inclusions is less than 50μ m in the slab samples.

Physical Simulation and Analysis of Flow Field of the Slab Mold

Dang Aiguo, Ren Ziping, Chen Yuanqing, Peng Shiheng, Liu Kun

2010, 31(4): 80-85.

Abstract(25) PDF(1)

Abstract:
With the slab mould of Lianyuan Iron and Steel Copany(LISC) as a prototype,the hydraulic model experiment is carried out.Through adjusting the casting speed and nozzle immersion depth,the flow form,Liquid surface wave and flow field impact depth are studied.the best parameters of slab caster for each section through this test are determinated,which provide a basis for further improving the product quality,the optimization of mould flow field and reducing cost.

Numerical and Cold Simulation on Gas Jet of Nozzle for Steel Slag Granulation

Li Junguo, Ceng Yanan, Han Zhijie, Long Yue, Xing Hongwei, Zhang Yuzhu

2010, 31(4): 86-91,97.

Abstract(15) PDF(1)

Abstract:
Granulation of liquid steel slag is the key process during heat recovery.The structure of gas nozzles and their layout should be designed to ensure solidification of slag drops before they falling to the ground.The flow field of gas jet with different structure was simulatd by Fluent software,and the simulation result was compared with that of cold model test.It was concluded that the combined laval-nozzle could provide concentrated and lower-expansion gas jet,and utilized to granulate liquid steel slag by gas quenching.The gas jet out of the combined laval-nozzle could be syncretized and stabilized at 250,265 and 300 mm,repectively,when the Mach numbers of laval-nozzl were 1.0,1.4 and 1.75.Consequently,the liquid steel slag could be granulated to drop and fly steadily when these combined laval-nozzle was utilized.The gas jet velocity at exit increased with the increase of Mach numbers of nozzle.Moreover,the gas jet temperature at exit declined,which could be beneficial to cooling slag drops.

Preparation of Soft Magnetic Ferric Oxide Powder from Purified Synthetic Rutile Mother Liquor

Wang Yanhua, Liang Ying

2010, 31(4): 92-97.

Abstract(14) PDF(1)

Abstract:
An investigation was made into the form of impurities like silicon,aluminum,calcium and magnesium present in the synthetic rutile mother liquor,which have some effects on the magnetic property of materials.By controlling pH value of the liquor and adding precipitation agent,a purified solution containing w_SiO₂ ≤ 16.7×10^-6、w_CaO<5×10^-6、w_MgO<5×10^-6、w_Al₂O₃<10×10^-6 was obtained based on orthogonal and validation tests.Then the purified solution was roasted to prepare ferric oxide powder for soft-magnetic use which is consistent with the standard SJ/T10383-1993YHT2.

2010 Vol. 31, No. 4