钢铁钒钛

Control of Mechanical Properties of Hot-dip Galvanized Ti-IF Steel Sheet

Zheng Zhiwang, Chen Jie, Wang Pingli

2006, 27(3): 1-4.

Abstract(22) PDF(1)

Abstract:
The hot dip galvanizing experiment of Ti-IF steel was carried out on a CGL line designed for the production of DQ and lower grade products. The effect of RTH strip temperature and skin-passing on the mi-crostructure, recrystallization texture and mechanical properties were investigated. The results show that, based on ULC Ti-IF steel, the hot dip galvanized sheet with excellent formability can be produced when suitable amount of excess Ti is ensured and suitable processing schedule is applied. Its yield strength, average r-value and n-value reach approximately 150 MPa, 2.5 and 0.25, respectively. However, after skin-passing, the yield strength increases obviously, the n-value and elongation decreases markedly. The n-value of final skin-passed products depends on ferrite grain size and becomes very low when the ferrite is coarsened. A strategy to ensure mechanical properties of hot-dip Ti-IF steel sheet by adjusting process parameter is discussed in terms of surface conditions of hot-dip galvanized steel sheet and application situation of customer.

Research on Extracting Ti（C,N） from High-titanium Slag

Li Ciying, Li Yawei, Gao Yunming, Yang Dabing, Li Yuanbing, Nie Jianhua

2006, 27(3): 5-9,20.

Abstract(29) PDF(1)

Abstract:
Based on thermodynamic analysis, titanium carbonitride were prepared by carbothermal reduction from high titanium slag which were compounded by TiO₂-CaO-SiO₂-Al₂O₃-MgO based on the titanium-bearing blast furnace slag of PZH Steel. The products of carbonthermal reduction process in different of atmosphere （argon, nitrogen） were confirmed. The phase composition and microstructure of sintered materials were investigated by X-ray diffraction and scanning electron microscope. The results confirm that the final products consist mainly of TiC in argon atmosphere and TiC_0.3N_0.7 in nitrogen atmosphere. The grain size of TiC in argon atmosphere is smaller about 2-4μm than Ti（C,N） in nitrogen atmosphere in the same of experiment condition.

Development of XCN-Z Mold Powder for Wide Slab Continuous Casting

Du Hengke, Wen Guanghua, Tang Ping

2006, 27(3): 10-13,20.

Abstract(15) PDF(1)

Abstract:
Compared with common slab continuous casting, the wide slab continuous casting is quite different. Based on studying the physical and chemical properties and insulation capacity of mold powders, the optimum physical and chemical indexes of mold powder were determined for medium carbon steel wide slab continuous casting and a mold powder （XCN-Z type） was developed. The industrial production shows that the developed XCN-Z mold powder for wide slab continuous casting has good behavior, it is satisfied for medium carbon steel plate continuous casting and direct rolling with 1.3~1.5 m/min casting speed.

Numerical Analysis on Uneven Deformation Behavior of Hot Strip in Rough Rolling

Guo Taixiong, Long Jinming, Zheng Zhiwang

2006, 27(3): 14-20.

Abstract(12) PDF(1)

Abstract:
According to the characteristic of adjusting width by erect roll at PZH Steel, the uneven deformation rule of slab during erect and horizontal rolling was analyzed by finite element simulation on base of MSC. Marc software. The effect of rolling process conditions on the width and size of head and tail of interim slab were also analyzed by numerical simulation. Trie results of simulation are accord with practical values. These results are helpful to find out some measures for hot rolling plant to decrease chip-off and increase incoming ratio.

Diffusion Welding of Titanium Alloy and Stainless Steel With Electroplated Nanometer Ni Interlayer

Huang Wenzhan, Sheng Guangmin, Qin Bin, Yuan Xinjian, Li Cong, Qiu Shaoyu

2006, 27(3): 21-25.

Abstract(23) PDF(1)

Abstract:
The diffusion welding of titanium alloy TA17 and stainless steel 0Cr18Ni9Ti with electroplated nanometer Ni interlayer was investigated. The elements distribution was analyzed by energy dispersion spec-trometry. The results show that the interlayer can prevent the elements interdiffusion of Ti, V, Al in titanium alloy and Fe, Ni, Cr in stainless steel effectively, restrain the forming of intermetallic compound TiFe, TiFe₂ and brittle phase TiC very well. The calculating results of activation energy show that the diffusibility of nanometer Ni is better than Ni foil in diffusion layer at joints.

Preparation of Photocatalytic Self-cleaning Ceramic Loaded Nano-TiO₂ Film

Tian Shouwei, Wang Zuohui, Liu Yangsi, Yan Jiazhen, Huang Wanxia

2006, 27(3): 26-30,37.

Abstract(16) PDF(1)

Abstract:
A self-cleaning ceramic loaded nano-TiO₂ was prepared by sol-gel process. The crystal structure and the crystal size of TiO₂ were characterized by XRD. The effect of the precursor's concentration and calcining heat on the ceramic's hydrophilicity and degradation of methyl orange under UV-light were investigated, and the adhesion of the film on the ceramic was also researched by testing the properties of the ceramic after brushed. The results showed that the higher the concentration of the precursor was, the bigger the grain fineness number was. The effect of the precursor's concentration on the film's hydrophilicity could be negligible, but the effect on the film's adhesion and degradation properties was obvious. The optimal calcining heat of the film was 500℃.

Research on Secondary Cooling Technologies for Continuous Bloom Casting

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

2006, 27(3): 31-37.

Abstract(13) PDF(1)

Abstract:
The secondary cooling scheme previous employed in continuous bloom caster was of following inadaptabilities for production of rail steel, such as the density of the secondary cooling and water distribution in secondary cooling zones. Therefore, the secondary cooling control scheme suitable for rail steel was developed on the basis of the variation of hot ductility with temperature and the distribution of strand surface temperature in secondary cooling zones, which improves internal quality of bloom heavy rail obviously. The operation shows that the center looseness and central segregation and shrinkage cavity are≤1.0, meanwhile, central segregation index of carbon is≤1.05, and the area ratio of equiaxed zone is≥30%. Internal quality and mechanical performance of the rails produced from continuously cast blooms have met the requirement of high-speed 350 km/h tracks.

Technical Measures for Increasing Lining Life of Refining Ladle

Ao Jinqing, Li Nan, Han Bingqiang, Wang Bo, Wang Huaibin

2006, 27(3): 38-43.

Abstract(16) PDF(1)

Abstract:
The technical measures for increasing the service life of refining ladle lining were presented, and the influence of service conditions on the life during the campaign were investigated. The practical results of two different projects were compared. The project A was that the ladle was lined with MgO-MA-C bricks on the whole wall and the project B was that the slag zone was lined with MgO-C bricks while the sidewall was lined with Al₂O₃-MgO-C bricks. The results showed that both project A and B could increase the service life remarkably, the ladle comprehensive life of the project A increased 7.2% and the average corrosion rate of slag zone decreased 15.8% compared with the project B in practical operation. Microstructure analysis of the used bricks from the ladle lining suggested that the formation of dense MA layer in the project A was the key to prolong service life. Besides, service conditions such as turnover time of ladle, steel liquid temperature, slag compositions and so on were also contributed to the service life. It was found that the life could also be improved effectively by stabilizing the ladle operations during the campaign and the refining process.

Study of Removing Tin Techniques for Reflow Conductor Roll

Fu Hanguang, Yan Lifen

2006, 27(3): 44-47,54.

Abstract(25) PDF(1)

Abstract:
Adhering tin is the main cause that reflow conductor roll abates which works in the electroplating tin line （ETL）. Removing the tin by means of chemical method is the important measures prolonging the servicing life of conductor roll. The tin remover whose main compositions are NaOH and KOH and assistant compositions are Na₂PbO₂ or K₂PbO₂ and NaNO₃ or NaNO₂ has excellent removing tin effect, while the temperature of removing tin liquid is 40- 80℃, and the temperature of conductor roll reaches 40-70℃. After removing the adhering tin layer of reflow conductor roll, the roughness of adhering tin conductor roll can resume to 4.0μm, its service life is increased by 80%, and repairing cost is decreased by 90%, and replacing conductor roll time can be obviously decreased, and production rate of ETL can be enhanced.

Influence of Train Velocity on Rail Contact Fatigue Damage and How to Select Rail for High-speed

Deng Jianhui, Liu Qiyue, Wang Feilong, Wu Xiongxian

2006, 27(3): 48-54.

Abstract(24) PDF(1)

Abstract:
The simulation tests of rail contact fatigue damage in varied railways were carried out at a professional test machine. The results show the rail wear decreases meanwhile the contact fatigue damage increases with the train velocity increase when the velocity is below 200 km/h, and both of them decrease when the train velocity reaches 300 km/h. The results accord with the numerical simulation on computer. So it is concluded that the heat treated rail whose tensile strength is 1 100 MPa should be selected when the train velocity is below 200 km/h, and U71Mn hot rolled rail whose tensile strength, crack birth rate, and crack extension rate are relative low, or other rail whose component and property are similar to the U71Mn hot rolled rail, should be selected when the train velocity approaches 300 km/h on the only passengers transport railway.

Study on Continuous Cooling Transformation of Vanadium Microalloyed Steel P510L

Yu Wanhua, Zhou Liquan, Han Jingtao, Zhang Zhongping, Liu Yong, She Guangfu

2006, 27(3): 55-59.

Abstract(29) PDF(1)

Abstract:
The CCT diagrams of vanadium microalloyed steel P510L were determined by dilatation method. The microstructures were analyzed by optical microscope. When the cooling rate was below 10℃/s, the mi-crostructures were coarse ferrite and pearlite, with the increase of cooling rate, the uniform fine ferrite and pearlite were found, while at the high cooling rate （above 35℃/s）, the bainite and ferrite were observed. According to SEM analysis, a lot of V precipitate were found. The V precipitate is 10-30nm in size with ball or cubic shape.

Appraisal of Roll Wear Pattern of CVC Mill

Xu Guang, Liu Xianjun, Xiong Junwei, Zhao Jiarong, Yu Xiaoqing

2006, 27(3): 60-62,68.

Abstract(17) PDF(1)

Abstract:
Large amount of measured data on roll wear of CVC mill in CSP production line were obtained and different roll wear patterns from F1 to F7 were investigated. The working roll wear of F1-F4 and F7 ws symmetric, while that of F5 and F6 wasn't symmetric. The self-keeping parameters and variance characteristic parameters of roll contour were calculated for each stand on the basis of measured data. The analysis and appraisal for roll wear of different stand were conducted. The working roll wear is even along longitudinal direction, and the self-keeping ability is quite well. This shows the roll crown of CVC mill is suitable, and it can guarantee good sheet shape.

Surface Defects and Control Measures of Stainless Steel Billet

Wang Wenxue, Wang Yu, Chi Jinghao

2006, 27(3): 63-68.

Abstract(20) PDF(1)

Abstract:
The differences of stainless steel and carbon steel were discussed in component, solidification character, performance under high temperature based on the function of [Ni], [Cr], [Ti] in stainless steel. The mechanism of major defects on stainless steel billet was investigated, which included surface depression, crack, slag inclusion. The effect of molten steel purity, casting temperature, performance of protecting slag, oscillation and liquid level control of mold in continuous casting on surface defect was studied importantly. Combining practical production of 0Crl8Ni9, 2Crl3 and Ti-stainless steel, the measures against depression, crack, slag inclusion and deep oscillation mark which can't be smoothed easily are put forward.

2006 Vol. 27, No. 3