钢铁钒钛

Study on Catalytic Mechanism of Reducing Hematite by Carbon at Low Temperature

Guo Peimin, Zhao Pei, Zhang Dianwei

2006, 27(4): 1-5.

Abstract(30) PDF(2)

Abstract:
The catalytic mechanism of reducing hematite was elucidated by experiments of Boudouard reaction and reducing hematite by CO gas and carbon.The rate of gasification reaction and reduction reaction was increased and showed similar tendency after addition of the catalyst.The catalytic effect of K₂CO₃ or Na₂CO₃ is substantially better than that of CaCO₃.The adding of catalyst seems to improve reactivity of carbon for hematite reduction,then accelerates the Boudouard reaction and promotes indirect reaction and direct reaction of hematite reduction,finally accelerates the reduction of hematite.

Study on Electromagnetic Stirring Parameter in Secondary Cooling Zone for Billet Continuous Caster

Wang Biao, Xie Zhi, Lin Guoqiang, Ji Zhenping, Liu Wenhong, Jia Guanglin

2006, 27(4): 6-9,24.

Abstract(19) PDF(1)

Abstract:
The thickness of solidified billet shell in secondary cooling zone was initial calculated by mathematics model and the pin-shooting situation was confirmed with the practical production situation of the continuous caster in EAF Steelmaking Plant of Nanjing Iron and Steel Co.Ltd.Crater end situation of Ø35～Ø55 mm was determined founded by calculation of modifying mathematics model making use of pin-shooting resulting in some casting speed and some steel grades and the F-EMS was fixed in the situation that is 8 m from the meniscus.The magnetic induction and electromagnetic force was measured under different electric current and frequency in different situation of the F-EMS in cold manner.Based on the measuring and calculating results,the optimal electromagnetic stirring parameters were confirmed,and the electric current was 550 A and frequency was 13 Hz.

Test and Analysis on Magnetic Field in M-EMS for Billet Caster

Zhou Liang, Tang Ping, Li Yongxiang

2006, 27(4): 10-13.

Abstract(30) PDF(1)

Abstract:
The magnetic field of in-mold electromagnetie stirrer（M-EMS）in Chongqing Iron ＆ Steel Company was measured.The magnetic field characteristic was discussed,and the relations of magnetic field and current,frequency and z direction in the mold were analyzed.The optimum frequency which was 4 Hz under working temperature was also figured out.This result could be helpful to optimize M-EMS process parameters.

Research on Mold Electromagnetic Stirring Technologies for Bloom Continuous Casting of Heavy Rail

Chen Yong, Yang Subo, Li Jianquan, Chen Lu:Ying

2006, 27(4): 14-20,24.

Abstract(31) PDF(1)

Abstract:
Metallurgical results of mold electromagnetic stirring（MEMS）in continuous casting previous employed at continuous bloom caster for heavy rail steel was not fully achieved.Therefore,experiments for optimizing process parameters of M-EMS for heavy rail steel was carried out.In order to analyze the influence of the current intensity on internal quality of heavy rail bloom,such as center looseness,central segregation and the ratio of equiaxed zone,the effects with different current intensity were investigated.On the basis,the MEMS scheme most suitable for heavy rail steel was developed,which improves internal quality of heavy rail bloom obviously.The operation shows that the area ratio of equiaxed zone is increased from 18.8% to 36.2 %,center looseness is≤1.5,central segregation and shrinkage cavity are≤1.0,meanwhile,the central segregation index of carbon is≤1.05.Internal quality and mechanical performance of the rails produced from continuously cast blooms have met the requirement of 350 km/h high-speed tracks.

Effect of Coiling Temperature on Microstructures and Mechanical Properties of Hot-rolled Bands of Ti-IF Steel

Zheng Zhiwang, Chen Jie, Zhou Dan

2006, 27(4): 21-24.

Abstract(30) PDF(1)

Abstract:
Effect of coiling temperature on microstructures and mechanical properties of hot-rolled bands of Ti -IF steel was studied by means of optical microscopy,X-ray texture measurement and tensile property testing.The results show that the hot bands not only exhibit fine-grained ferrite measured to be approximately ASTM grade 11.0 but also show obvious textures.The main texture components were {115}〈110〉,{223}〈110〉and {332}〈110〉along a fiber.The coiling temperatures during hot rolling seems to have little effect on the ferrite grain size,whereas the microstructure seems to be more homogeneous and the density of all above -mentioned texture orientations seemed to decrease with the increasing of coiling temperature.Increasing coiling temperature causes strength to drop and elongation to increase at first and then to decrease.

Experiment on Synthetic Slag for Si-killed Steel Desulphurization

Hao Ning, Wang Haitao, Wang Xinhua, Li Hong, Wang Wanjun

2006, 27(4): 25-28.

Abstract(24) PDF(2)

Abstract:
Top slag plays a very important role for desulphurization during ladle refining.To prevent[Al]increasing,a synthetic slag without alumina （CaO-SiO₂-CaF₂）has been chosen for Si-killed steel.The laboratorial results show that the synthetic slag with initial composition of CaO 66%,SiO₂ 17%,CaF₂ 15% and Si 2% has high desulphurization speed and efficiency.The desulphurization time from 0.008 % to 0.001% is only 10min,this can satisfy the need of high performance casting.

Steelmaking Process of V Micro-alloying High Strength Steel in EAF

Mao Xinping, Chen Xuewen, Li Liejun, Xu Chuanfen, Zhuang Hanzhou, Yan Xuchang

2006, 27(4): 29-33.

Abstract(28) PDF(1)

Abstract:
Based on the research for metallurgical characteristics of EAF and utilizing the feature of high N content in EAF steelmaking,a V micro-alloyed high strength hot rolling steel plate with 550 MPa yield strength has been successfully developed by using VN alloy in the V micro-alloying treatment.The aim is that:[O]≤0.025%,[S]≤0.005%.The yield of V element is above 90% and that of N element is 60%～70% by applying the technical measures of increasing VN alloy yield in the EAF steelmaking,this is helpful to the grain refinement and precipitation strengthening effects of V in steel.

Study on Static-recrystallization and Continuous Cooling Transformation of Undercooling Austenite for X60 Pipeline Steel

Peng Haihong, Chen Ye, Li Guobao, Luan Yuwu

2006, 27(4): 34-37.

Abstract(24) PDF(1)

Abstract:
The static recrystallization of X60 pipeline steel was measured by double-pass compression test on a Gleeble-1500 thermomechanical simulator.The expanding curves and continuous cooling transformation curve （dynamic CCT curve） of X60 pipeline steel were obtained by dilatometry and microscopic test under different cooling speed.The transformation of austenite and morphology of X60 in the course of continuous cooling were analyzed.The analyzing results in recrystallization and dynamic CCT curve could provide the references for determining the controlled rolling and controlled cooling parameters in practice.

Thermodynamic Analysis on Direct Alloying of V₂O₅

Zhou Yong, Li Zhengbang

2006, 27(4): 38-42.

Abstract(21) PDF(1)

Abstract:
The equilibrium composition of V₂O₅ and reductant during direct alloying of V₂O₅ as a complex system composed of muti-component and multi-phase were simulated by HSC and then analyzed.The result of thermodynamic calculation shows that the reduced products of V₂O₅ carbothermic reduction is the carbide of vanadium,the system of silicothermic reduction should add CaO,aluminothermic reduction can reach a reduction rate of 99%,the reduction ability of Al is more effective than that of C and Si.The complex silicothermic and aluminothermic reduction can reach a high reduction rate by using a small quantity of Al,the calculation result is consistent with the thermodynamic law of the industrial practice of making ferrovanadium by electricity -silicothermic method.

Effect of Vanadium on Deformation Induced Phase Transformation of High Nitrogen Steel

Zhang Kaihua, Yong Qilong

2006, 27(4): 43-47.

Abstract(24) PDF(1)

Abstract:
The microstructure and ferrite volume fraction of high-nitrogen vanadium steel and the base steel were studied with Gleeble-3500 simulator and optical microscopy.The effects of vanadium on deformation induced ferrite transformation of high-nitrogen steel were analyzed.The results showed that vanadium promote the deformation induced ferrite transformation,increase the volume fraction of deformation induced ferrite,and refine ferrite grain.

Effect of Sulphide on Fatigue Crack Initiation of W6Mo5Cr4V2 Cold Ring-rolling Mandrel

Xu Jianbing, Yu Jixing, Su Kai

2006, 27(4): 48-52.

Abstract(24) PDF(1)

Abstract:
There is plus-minus duplicity in the effect of sulplide inclusion on fatigue crack initiation.The effect of sulplide shapes,size,distribution and mechanical property on the fatigue fracture of high speed steel W6Mo5Cr4V2 cold ring-rolling mandrel is analyzed.It is considered that soft sulplide has some effects on brittle inclusion,such as encapsulation and buffering.These effects could slow up the mosaic stress of hard brittle non-metal inclusion to the matrix and inhibit the initiation of fatigue crack,however the inelusian still acts as rending to the matrix.

Application and Development Trend of Advanced High Strength Steel for Auto

Su Kai, Yu Jixing, Xu Jianbing

2006, 27(4): 53-57,62.

Abstract(19) PDF(1)

Abstract:
Main progress in the advanced high strength steel and its applications in the automobile industry are reviewed.The theorem,composition,characteristic of several advanced high strength steel are given in details,which includes BH steel,DP steel and TRIP steel.Furthermore,the present application and developing situation of the above-mentioned high strength steel were introduced too.The reduction of stretch flange ability and bend formability and the increase of rebound and bend dehiscence in forming processes are introduced. It is pointed out that the development of high strength steel should combine with the improvements of forming techniques.Furthermore,the development trend of high strength steel are introduced,it is that the safe and formability should be thought about in addition to increasing strength and lighting for automobile.Meanwhile, the new strengthening method for increasing strength and ductility should be developed.

Spectroscopic Analysis Method of Vanadium in Ti-based Alloy

Liu Ping, Liu Haoxin

2006, 27(4): 58-62.

Abstract(21) PDF(1)

Abstract:
The characteristics of visible light spectrum used for spectroscopic analysis of vanadium in Ti-based alloy were investigated with grating spectroscope and prism spectroscope.The visible light spectra of V and Ti were simulated by computer system and the color spectra were shot with spectroscope.The characteristics of analytical spectrum at V437.92 nm,V459.41 nm and V485.15 nm line groups in Ti-based alloy were investigated,so the analysis chart and intensity mark for semi-quantitative analysis were obtained.The method was developed for spectroscopic analysis of vanadium in Ti-based alloy and the investigation was made on the distinction of alloy mark.The methods could meet the requirement for qualitative analysis and semi-quantitative analysis of vanadium in Ti-based alloy and could be used to exactly distinguish alloy and avoid the commixing of material on spot.

2006 Vol. 27, No. 4