钢铁钒钛

Effect of Technical Parameters on Synthesized Vanadium Carbonitride by One Step Method

Yu Sansan, Fu Nianxin, Gao Feng, Sui Zhitong

2007, 28(4): 1-5.

Abstract(20) PDF(1)

Abstract:
The effect of technical parameters on nitrogen content in vanadium carbonitride is investigated.The results show that the ratio of V₂O₃ to C is evident effect on the nitrogen content of products,and the nitrogen content could reach maximum if the carbon content is over 15%.The nitrogen content of products first increases and then decreases with the rising of reactive temperature,and the nitrogen content reaches maximum at 1400℃.The XRD patterns show that the experimental product is composed of VN and VC solid solution when the reaction temperature is 1280~1480℃.The nitrogen content of products trends to increase with the prolonging of reaction time,and the products are appropriate then the reaction time is 120min.The reaction time also influences the grain of products.Based on the SEM,the grain size of the products coarsens with the prolonging of reaction time.The additives(NH₄Cl and Fe) have evident effect on the nitrogen content of products.

Research on Residence Time of Panzhihua Ilmenite Particle in a Fluidized Bed with Inner Structural Parts

Chen Deming

2007, 28(4): 6-11.

Abstract(21) PDF(1)

Abstract:
The effects of apparent air velocity,feeding rate,particle diameter and gap of the baffles on the residence time and bed pressure drop of Panzhihua ilmenite particles are investigated in an experimental fluidized bed with inner structural parts composed of a series of horizontal baffles whose porosity ratio is 30%.The experimental results show that the horizontal inner structural parts in fluidized bed can avoid slugging,crash air bubble,intensify solid particles contact with air,restrain particles back mixing and improve the fluidizing of ilmenite particles in bed,so it is propitious to air-solid reaction greatly.

Effect of N-V MicroaUoying on Strength and Toughness of Low Carbon Weathering Steel

Wang Bo, Wang Deyong, Liu Chengjun, Jiang Maofa

2007, 28(4): 12-16.

Abstract(20) PDF(1)

Abstract:
The weathering steel with N-V micralloying is produced in a vacuum induction furnace.The microstrueture was analyzed by metallographic microscope and TEM,and the strength and toughness of experimental steel is characterized by tensile test,impact test and fracture analysis.The results show that the low carbon weathering steel with N-V microalloying has excellent plasticity and high strength and toughness.The microstrueture consists of equiaxed ferrite and a small amount of aberration pearlite(5% volume fraction)as well as similar granular bainitie formed in part of ferrite grain(30% volume fraction).Fine ferrite grain is gained with N-V micoalloying and the average size of ferrite grain was 7.8μm since the disperse precipitation of VN particles.

Research on V-N Microalloyed Steel for Offshore Oil Drilling Platform

Guo Hua

2007, 28(4): 17-21.

Abstract(25) PDF(1)

Abstract:
The V-N mieroalloying technology is applied in designing the chemical composition of E36 grade experimental steel for offshore oil drilling platform.The experimental steel is rolled according to TMCP,and its mechanical properties could satisfy the requirements of the nation standard GB712-2000《Structure Steel for Ship Body》.

Effect of Vanadium on Microstructure and Property of Fire- resistant Weathering Steel

Liu Qingchun, Zheng Zhiwang, Liu Yong

2007, 28(4): 22-28.

Abstract(12) PDF(1)

Abstract:
In order to investigate the influence of vanadium on the microstructure and properties of fire-resistant weathering steel,the effect of vanadium on CCT diagram,microstructure and tensile properties at both room temperature and high temperature up to 600℃with different kinds of hot-rolling process are researched by dilatometer, electronic microscope,phase analyzing,tensile test and so on.The relationship of the microstructure and property is analyzed.It is found that adding vanadium can raise the temperatures of phase change.The function of vanadium depends on the amount of precipitated phase,which would be finer and denser as the amount of adding vanadium rising,whereas the addition of V increasing from 0.10% to 0.20% promotes the formation of polygonal ferrite.The present of proper bainite fraction in the microstructure is essential for fire-resistant weathering steel in order to obtain enough high-temperature yield strength and high yield strength ratio(YS ratio).

Numerical Simulation on Molten Steel Flow and Carbon Concentration Distribution in Ladle during RH Vacuum Degassing Process

Gao Aimin, Liang Juan, Ai Liqun, Zhang Xiang

2007, 28(4): 29-35.

Abstract(22) PDF(1)

Abstract:
According to the actual production condition of RH-MFB in one plant,the coupling mathematic model of molten steel flow and carbon concentration distribution in ladle is established by using the commercial code CFX.The flow characteristic of molten steel and variation of carbon concentration are investigated,and the validity of mathematic model is verified by comparing simulation results with measuring results.Carbon concentration distribution is analyzed at the last stage of decarburization,and the influence of process equipment on decarburization process is discussed.So some useful theoretical evidence instructions are put forward for ultra-low-carbon steel production.

Research on Secondary Cooling Technologies for Bloom Continuous Casting of High Vanadium and Nitrogenous Weathering Steel

Chen Yong, Yang Subo

2007, 28(4): 36-41.

Abstract(35) PDF(1)

Abstract:
Aim to optimize the secondary cooling scheme employed in continuous bloom caster for production of weathering steel for 310 Z-beam,which included the density of the secondary cooling and water distribution in secondary cooling zones,a series of improving measure was carried out.The improving measures include increasing the length of secondary cooling zones and the specific water flow,adjusting the water flow distribution among the secondary cooling zones,so the optimum secondary cooling control scheme is developed,which improves internal quality of bloom 310 Z-beam obviously.The practical operation shows that the ratio of center looseness ≤ 1.0 is increased from 79.71% to 90.70%,the ratio of central segregation<0.5 is increased from 1.45% to 44.19%,the free central shrinkage cavity is increased from 86.96% to 93.02%,while,the free center line crack is increased from 39.13% to 62.79%,the free intermediate crack is increased from 85.51% to 88.37%, the free sub-surface crack is increased from 78.26% to 97.67%,and the free comer crack is increased from 73.91% to 93.02%.The qualified blooms are delivered to produce 310 Z-beam which R_eL is ≥ 450 MPa.

Study on Contact Fatigue Damage of Steel Rail

Deng Jianhui, Wang Feilong, Wu Xiongxian, Ning Xiongxian

2007, 28(4): 42-47.

Abstract(27) PDF(1)

Abstract:
A test method of rail's contact fatigue is developed,which is different from the conventional test method and much similar to the true contact conditions on the practical rails.The simulated test for the anticontact-fatigue property of different kinds of rails is carried out,in which the velocity is 160 km/h,the radius is 800m,and the axle weight is 25t.The results indicate that the contact fatigue damage is relatively slight for the rail which has slow crack initiation and expansion ratio and large wearing-away in the given test conditions (work condition).The contact fatigue damage of U75V hot-roll rail with 1 000 MPa strength level is the most serious in all kinds of the tested rails.According to the features of contact fatigue damage,the heat -treated rail with 1300 MPa strength level should be used on the small radius or the heavy-duty line,and the rail with slow crack expansion ratio should be used on the high speed or fast line.

Study on Roll Shape of Temper Mill for Hot-rolled Pickled Plate

Zhang Zhongping, Li Junhong

2007, 28(4): 48-51,66.

Abstract(23) PDF(1)

Abstract:
According to the technological conditions of hot-rolled pickled plate,a mathematic model is constructed to optimize the roll shape of temper mill,in which the distribution uniformity of the front tension in transverse and the contact pressure between mils is taken as the objective function.The model has been used to optimize the roll shape of temper mill for hot-rolled pickled plate in PZH Steel,and the quality of hot-rolled pickled plate is improved.

Study on Controlling Nitrogen of Wheel Steel Produced by BOF-LF-VD-CC Process

Guo Shangxing, Wang Jianjun, Zhou Li, Liu Yiqiang, Fan Dingdong, Shi Huaiyan, Jiao Xingli, Liu Qilong, Wang Guocai

2007, 28(4): 52-55,70.

Abstract(24) PDF(2)

Abstract:
According to conventional technological conditions of producing wheel steel at Ma'anshan Iron and Steel,the Variation of nitrogen content in the liquid steel was determined through industrial experiment.The results show that the main procedure of the nitrogen absorption in the LF→VD→CC process includes the LF, from ladle to tundish and from tundish to mould,the nitrogen absorption in the LF process is higher than that in the others,the average nitrogen absorption is about 28×10^-6,and the maximum value is about 50×10^-6.The prevention measures of nitrogen absorption are discussed,and the effect of denirtiding in VD process is significant.The average denitriding rate is about 30% and average denitriding value is 21×10^-6.The main factors affecting the denitriding in VD process and the optimum technological parameters in VD process are analyzed.

Effect of Heat Treatment on Microstructure and Property of High Boron and Low Carbon Cast Steel

Shi Wenxiao, Fu Hanguang, Jiang Zhiqiang, Huang Liming, Xing Jiandong

2007, 28(4): 56-61.

Abstract(38) PDF(1)

Abstract:
A high boron cast steel with high strength and wear-resistant is obtained by adding 1.0% B to the low carbon steel whose carbon content is <0.2%.The effect of quenching temperature on the microstructures and properties of high boron cast steel is investigated.The results show that the unitary martensite matrix can be obtained by quenching at 900~1050℃,and the hardness of high boron cast steel has no obvious change when the quenching temperature is changed.With the rising of quenching temperature,the boride transforms from continuous networked into broken network,and the impact toughness of high boron cast steel increases.After the quenching temperature being above 1000℃,the impact toughness has no obvious change.Moreover, high boron cast steel has excellent wear resistance quenching at 900~1050℃.

Computation on Temperature Fields of ESR Slab Ingot

Chang Lizhong, Li Zhengbang

2007, 28(4): 62-66.

Abstract(21) PDF(1)

Abstract:
An unsteady-state model of electroslag remehing (ESR) slab ingot is established,and the temperature field of slab ingot is calculated.The metal pool depth at different height of ingot is obtained with different melting velocity.The factors influencing the pool depth and the solidification behavior of ingot are discussed. The results show that melting velocity is the most important influence factor for the pool depth,the system is in the quasi-steady state and the pool depth doesn't change when the ingot gets to a certain height.Meanwhile, the cooling conditions in the bottom of ingot have little effect on the pool depth.

Analysis on Causes of Cavity Defect for Hot Rolling Plate

Su Hezhou

2007, 28(4): 67-70.

Abstract(23) PDF(1)

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The causes of cavity defect are analyzed and it is concluded that the unsuitable technological parameters during continuous casting are the main causes.The influence of casting speed,argon blowing flow and insertion depth of submerged nozzle on the distribution of gas bubble in mould is investigated by water modelling. So the prevention measures of cavity defect are put forward for the hot rolling plate and the production tests indicate that the measures are effective.

Du Houyi

2007, 28(4): 71-74.

Abstract(16) PDF(1)

Abstract:

2007, 28(4): 75-77.

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2007 Vol. 28, No. 4