钢铁钒钛

Discussion on Two-step ApproachTechnology of Smelting FeV80

Sun Zhaohui, Yang Yang jun, Zhang Fan

2010, 31(1): 1-4,23.

Abstract(22) PDF(3)

Abstract:
The possibility of smelting FeV80 by two-step approach was discussed with the application of 650 kVA arc furnace.It is figured out that the key to the problem is controlling the quantity of vanadium-rich slag and the recovery percent of FeV80 is improved to 97.28%, with about 1.8% increase comparing with one-step method.

Study on the Reaction Mechanism of FeO and V₂O₅

Xie Bing, Cao Hailian, Guan Ting, Diao Jiang, Zhu Xuehui

2010, 31(1): 5-10.

Abstract(20) PDF(1)

Abstract:
On the basis of theoretical analysis, the reaction mechanism of FeO and V₂O₅ is studied by differential scanning calorimetry (DSC), high-temperature quenching and X-ray diffraction analysis (XRD).The experiment results indicate that V₂O₅ is broken down into V₂O₃ and oxygen, FeO is oxidized to Fe₂O₃, V₂O₃ reacts with FeO to form FeV₂O₄, V₂O₅ reacts with Fe₂O₃ to form FeVO₄, V₂O₃ reacts with FeO and Fe₂O₃ to generate Fe₂VO₄.Fe₂O₃ and V₃O₅ are formed when the temperature is between 830℃ to 970℃ and the mass percent of the FeO is less than 50%, FeVO₄ is formed when the temperature is between 970℃ to 1 270℃ and the mass percent of the FeO is between 50% to 70%, Fe₂VO₄ is formed when the temperature is more than 1 270℃ and the mass percent of the FeO is more than 35%.

Research on Oxidation Behavior of CP Titanium TA2

Huang Deming

2010, 31(1): 11-16.

Abstract(22) PDF(2)

Abstract:
Oxidation behavior of commercial titanium TA2 was investigated at various atmosphere temperatures ranging from 650℃ to 1 000℃.The results show that oxidation rate was low at temperature below 800℃, and no peeling of oxide film was observed even holding for 6 hours.However, when atmosphere temperature exceeded 800℃ the oxidation tends to be aggressive, oxide film was found breaking off after oxidation for 30 minutes.SEM observation indicated that oxide layer composed of an oxide film and an oxide-rich layer.The oxide film is a mixture structure by several types of titanium oxides which are porous, brittle and readily break off, while the oxide-rich layer is a solid solution where oxygen atoms dissolved into titanium matrix.This oxide-rich layer is brittle but closely adhered to matrix and creates challenges for breaking down.XRD analysis pointed out that phase structure of oxide layer mainly contains TiO₂, TiO_0.325 and TiO_0.48.

Study on the Process of Adding TiO₂ and VC Superfine Particle to Molten Industrial Pure Iron

Wang Guocheng, Huang Lang, Fang Keming

2010, 31(1): 17-23.

Abstract(17) PDF(1)

Abstract:
Ingot specimens were obtained by the process of adding individual 80 nm TiO₂ and 1.5 μm VC superfine particles to molten industrial pure iron.Nonmetallic inclusions were extracted from industrial pure iron ingot sample by the electrolytic method in the nonaqueous solution.Morphology, existent state and components of inclusions were investigated by SEM and EDS.The results showed that additive TiO₂ and VC particles usually combine with microelements and molten inclusion form complex inclusions, and existed in the interior of complex inclusions.There were a lot of white punctate and ribbon MnS inclusions at some surface of VC complex inclusions.Stability of additive TiO₂ and VC superfine particles in molten is also investigated by thermodynamic calculation.

Study on Optimization of LF Argon Blowing at Ladle Bottom by Hydraulic Model

Li Youqi, Yu Huacai, Kou Zhiqi, Zhao Jizeng, Hua Yuancai

2010, 31(1): 24-29.

Abstract(20) PDF(1)

Abstract:
The hydraulic modle of refining LF argon blowing of Benxi Iron and steel Co.was simulated, the effects of optimization argon blowing method on mixing time of molten steel was studied at the same time.In addition, the influence of quantities of gas supply on mixing time of molten steel and inclusion was investigated.The results show that:the optimization argon blowing method can be gained besides the electrode collar area, which is the position of present ladle argon blowing.The mixing time of molten steel can be reduced obviously by adopting the optimization argon blowing method.In addition, the mixing effects of molten steel is the best when two permeable bricks work as 30° included angle and the position is simultaneously located in the 1/2 radius, besides, the included angle is 150° if the position is located in the 2/3 radius.Moreover, the mixing effects of permeable bricks lying 1/2 radius has obvious superiority compared with permeable bricks lying 2/3 radius under the same condition.The quantities of gas supply should be properly, too much amount of gas has no obvious effect on the mixing time, on the contrary, too much amount of gas can lead the slag into the molten steel.

Optimization of Flow Control Devices in Four-strand L Type Tundish by Water Modelling

Li Jingshe, Ma Yu, Chang Guoping, Yang Shufeng, Yang Mingsheng

2010, 31(1): 30-35.

Abstract(21) PDF(1)

Abstract:
A four-strand L type tundish in the steel plant of Xinxing Ductile Iron Pipes Co., Ltd., was studied.On the basis of similar principle, a 1:2 physical model of four-strand caster tundish was built.The simulating study shows that the internal structure of the prototype tundish was unreasonable, existing a large dead zone, the largest dead area ratio was 66.2%;There was a large difference in flow characteristics exiting between the four outlets of the tundish.So the original design of the tundish can not meet the technical requirements for inclusion floatation and temperature homogenization.Among all kinds of optimization cases, "baffle+single-blowing" (case C) and "baffle+single-blowing+turbulence inhibitor" (case D) are ideal optimization cases.Case D has the smallest dead zone proportion and the longest average residence time, with the dead zone proportion 19.7%, dropping 15.2% than the prototype, and the average residence time was 433 s, increasing 83 s than the prototype.

Study of Water Modeling and Metallurgical Effects on Argon Blowing at Tundish Bottom

Cui Heng, Tang Dechi, Bao Yanping

2010, 31(1): 36-39.

Abstract(20) PDF(1)

Abstract:
The influence of argon blowing at tundish bottom on flow field in tundish was studied by water modeling and industrial trial.Water modeling results showed argon bubbling could improve flow field obviously.The optimum argon blowing parameter is that the distance of permeable brick and ladle nozzle is 765 mm and argon blowing volume is between 0.06 m³/h and 0.10 m³/h.Industrial trial results showed the total oxygen content of slab was decreased 26.67% after acting argon bubbling curtain in tundish.With argon blowing, large-sized inclusions content of slab decreased from 0.430 mg/kg to 0.079 mg/kg.

Effect of Cold-rolling Reduction on the Microstructure and Texture of a Continuously Annealed Ti-IF Steel

Zheng Zhiwang, Liu Qingchun, Li Xusheng

2010, 31(1): 40-45.

Abstract(19) PDF(1)

Abstract:
According to the process of a continuous hot-dip galvanizing line, salt bath annealing simulation was conducted to study the evolution of microstructure and textures of acommercially produced Ti-IF steel during cold-rolling and annealing by means of optical microscopy and X-ray texture measurement with emphasis on the effect of cold-rolling reduction on the microstructure and the textures.The results showed that as the cold-rolling reduction increases from 60% to 90%, the textures along α fiber skeleton are constantly enhanced and {223}<110> and {114}<110> tended to be the main textures.On the other hand, {111}<011> and {111}<112> texture along γ fiber skeleton are also improved.The ferrite grain size after annealing was refined from ASTM No.9.0 to No.10.5.The tested steel still exhibited stronger {223}<110> and {114}<110> textures and the {111} texture tends to be increased with the cold-rolling reduction.The cold-rolling reduction should be kept above 80% in order to obtain strong {111} texture.

Influence of Isothermal Treatment on Formation of Intra-granular Ferrite in Magnesium Treated High-grade Pipeline Steel

Zhao Hui, Li Zhen, Wu Huibin

2010, 31(1): 46-50.

Abstract(27) PDF(1)

Abstract:
The effect of isothermal treatment at temperatures in the range of 700, 650, 600 and 550℃, and that of isothermal holding time at 600℃ on formation of intra-granular ferrite (IGF) in Mg treated steel were studied by using thermal simulation.Vickers hardness test was also carried out for the steel isothermally treated at different temperatures, and the constituent of the inclusions that enhance the formation of intragranular ferrite was analyzed by EDAX.The results show that the amount of IGF reach to maximum at 650℃and the hardness of the steel decreases at first and then increases, when the isothermal temperature decreases from 700℃ to 550℃.However, intra-granular ferrite disappears when the isothermal temperature decreases to 550℃.It is found that IGF and bainite competed to form in the austenite grains at 600℃.The further analysis indicates that inclusions consisting of Mg, Al and Ti could induce the IGF nucleation.

Effect of Cooling Process on Microstructure and Mechanical Properties of High Strength Fracture Splitting Connecting Rod in Auto Engine

Zhang Xianzhong, Zhou Guifeng, Chen Qingfeng, Xiong Yuzhang, Cai Qizhou

2010, 31(1): 51-55,61.

Abstract(24) PDF(1)

Abstract:
The effect of cooling process on microstructure and mechanical properties of high strength microalloyed medium-carbon steel fracture splitting connecting rod in auto engine was studied using the method of microscope, SEM and TEM, etc.The results show that high cooling rate after finished rolling can increase the percentage of pearlite, decrease the grain size of ferrite and lessen interlamellar spacing of pearlite.The precipitation phases in the steel are composite phase of (V, Ti) (C, N) with variants of the B-N orientation relationship to the ferrite.Their granularity are about 30~170 nm, and they will decrease with the speeding up cooling.The yield strength is improved with increasing the cooling rate after finished rolling, and in case of high cooling rate, the yield strength can reach to 770 MPa, with the contributing of the precipitation strengthening to yield strength being 174 MPa.

Research on the Non-metallic Inclusion in 20CrMnTi Steel During the Process of Refining and Casting

Li Junguo, Ceng Yanan, Wang Shuhua, Li Shouzhang

2010, 31(1): 56-61.

Abstract(22) PDF(1)

Abstract:
Use the methods of metallographic observation, sample-electrolysing, SEM and EPMA, the quantity, dimension, morphologies and composition of non-metallic inclusions in 20CrMnTi steel were investigated.It was suggested that lots of non-metallic inclusions were removed from molten steel during LF refining.The T[O] and [N] contents in slab were 18.53×10^-6 and 46.94×10^-6, respectively, as some air could be inhaled into molten steel.The volume ratio of micro-inclusion in slab was being from 0.085% to 0.11%.The micro-inclusions in molten steel and slab, which were typical production during deoxidization and desulfurization, were comprised with oxide, sulfide, calcium silicates and calcium aluminates inclusions.The quantity of large-scale inclusions in molten steel in tundish and slab were 1.011 mg/kg and 0.785 mg/kg.These typical complex inclusions were silicates and silicate aluminates with higher contents of K₂O and Na₂O, which were the main components in mold powder.

Dynamic Soft Reduction Technology for 360mm×450mm Bloom Caster

Chen Yong, Xiao Mingfu, Wu Guorong

2010, 31(1): 62-68.

Abstract(22) PDF(1)

Abstract:
The dynamic soft reduction technology for 360 mm×450 mm bloom caster and its application results at PISCO (Panzhihua Iron & Steel Co.) were presented.Experiment for contrasting process with or without soft reduction for bloom was investigated, in order to analyze the influence of the soft reduction on internal quality of bloom, such as center looseness and central segregation.The operation shows that after applying the soft reduction to bloom of alloy steel, the ratio of center looseness which is ≤ 1.0 increases from 66.67% to 85.71%, central segregation which is ≤ 1.0 is increases from 94.44% to 100%, central shrinkage cavity which is free increases from 88.89% to 96.42%, and central segregation index of carbon decreases from mean value of 1.15 to 1.05.These results have provided important technology supports for PISCO to optimize the steel product structure, and to improve the production of high quality, property, and value added products.

Study on Microstructure and Properties of V-Ti-N Weathering Steel

Li Jun, Shi Qingnan, Li Zhengrong

2010, 31(1): 69-73.

Abstract(20) PDF(1)

Abstract:
The dynamic CCT diagrams, precipitated V, grain size and strength for V-Ti-N weathering steels containing 0%V, 0.05%V, 0.10%V and 0.15%V respectively have been examined.In the study, the equipments such as vacuum induction furnace, hot simulation test, ICP emission spectrometer, optical microscope, TEM and electronic tensile tester were used.The results show as follows:addition of 0.10%V into weathering steel has a limited effect on dynamic CCT diagrams and Bs temperature of bainite transformation for 0%V and 0.10%V steel is below 600℃;the grain size of V-Ti-N weathering steels is 6.2~7.8 μm and make a contribution of 101~175 MPa to precipitation strengthening.Yield strength increases with the increase of V×N product, but the strengthening efficiency decreases gradually;V-Ti-N micro-alloying is better fit for development of 400 MPa and 450 MPa high strength weathering steel for which V content should be less than 0.10%.

Analysis of Controlling Oxygen Activity in IF Steel at Blowing End-point of BOF Steelmaking

Feng Jie, Bao Yanping, Yue Feng, Wu Xun, Tang Dechi

2010, 31(1): 74-78,92.

Abstract(20) PDF(1)

Abstract:
Oxygen activity at blowing end-point of BOF steelmaking is the main source of producing non-metallic inclusions and has bad influence on steel cleanliness.In order to increase the control of oxygen content at blowing end-point of BOF steelmaking and improve products' inner quality, experiments are done during a BOF steelmaking to produce IF steel in a plant.The content of carbon and oxygen at blowing end-point is analyzed, the effect of content of carbon, BOF age, end-point temperature and consumption of oxygen on the content of oxygen at blowing end-point are studied and decreasing measurements of end-point oxygen content are put forward.

Numerical Simulating for Phase-change Heat Transfer Process of Slag Granule

Xing Hongwei, Wang Xiaodi, Long Yue, Zhang Yuzhu

2010, 31(1): 79-83.

Abstract(17) PDF(3)

Abstract:
The physical and mathematical models of solidification process of spherical molten steel slag granule have been established in this paper.The temperature fields of slag sphere and its outer gas could be calculated through the FLUENT software.Consequently, the solidification time of the slag sphere with different diameter could be gained.It is believed that the numerical simulated results would provide the theoretical basis for granulating molten slag and heat recovery equipment layout of molten slag.The numerical simulation results showed that liquid slag sphere could release more than 80% of the phase-change heat in 2 s when the initial condition as follows:the temperature of molten slag being 1 823 K, the diameter of granule being 1~3 mm, the temperature of cooling gas being 373 K, the velocity of gas flow being 1~20 m/s.It is concluded that there could not be conglutination between slag spheres after a certain of cooling time if the molten steel slag has been granulated to 1~3 mm spheres.

Study on Acid Evaporation and Valuable Metal Elements Recovery in Stainless Steel Pickling Waste Liquors

Zhao Junxue, He Hui, Ma Hongzhou, Li Xiaoming, Cui Yaru

2010, 31(1): 84-87.

Abstract(19) PDF(1)

Abstract:
Aimed at the disadvantages in relevant techniques of stainless steel pickling waste liquors, evaporation test is carried out to take the rest acid in the waste liquor and recovery the valuable metal element.Different evaporation process with different addtion amount of sulphuric acid are tested.It is found that addition of sulphuric acid can promote the evaporation of HNO₃ and HF obviously.The reasonable propotion of H₂SO₄ addtion is about 10%.The content of valuable metal, such as Ni, Cr, and Fe in residual liquors can be doubled after evaporation treatment.This will be in favor of the effective use.

The Features and Advances of Technology of Zhusteel Electric Shaft Furnace

Zou Anhua, Wang Xinhua

2010, 31(1): 88-92.

Abstract(21) PDF(1)

Abstract:
Through improvements of equipment of an intensive use of oxygen, continuous feed iron etc., and advances of technology such as foamy slag, charge mixture, distribution of charge, end-point control etc., the steelmaking index of Zhusteel electric shaft furnace is among the world's advanced ranks.Its successful experience is worthy to other large-scale EAF, particularly for large-scale finger electric shaft furnace.Fuchs finger electric shaft furnace adding hot metal and enhancing usage of oxygen may be one of the best way to reduce costs and to improve productivity of EAF in the future.

2010 Vol. 31, No. 1