钢铁钒钛

Effect of Vanadium on Ferrite Grain Size after Rapid Cooling

Zhang Kaihua, Yong Qilong

2007, 28(3): 1-4.

Abstract(16) PDF(1)

Abstract:
The ferrite grain size and yield strength of the middle and low nitrogen vanadium steel are investigated after rapid cooling as rolled. The experimental results show that the ferrite grain size of vanadium steel is finer than that of base steel since the vanadium being dissolved in matrix. It can be conclude that dissolved vanadium decreases the actual phase transfonnation temperature of steel and then ferrite grain is refined.

Effect of Nitrogen on Structure and Property of Ultra-fine Austenitic Stainless Steel

Peng Bing, Liu Jing, Li Guangqiang, Zhang Xin

2007, 28(3): 5-10.

Abstract(27) PDF(1)

Abstract:
The structure and property of ultra-fine austenitic stainless steel with different content of nitrogen made by mechanical alloy (MA) and the spark plasma sintering (SPS) technology are investigated. The XRD-pattern show that sintered sample with nitrogen is composed of single austenite, while that without nitrogen is composed of austenite and martensite. TEM shows the grain size of sample all distributes in nanometer. The grain size of sample with nitrogen is smaller than that without nitrogen. The hardness and abradability of sintered sample increase with the rise of nitrogen. The tensile strength of sintered sample increases at first and then decreases with the rise of nitrogen. Measurement of polarization curve shows that the corrosion resistance of sintered sample is enhanced with the rise of nitrogen.

Research on Inclusion in 20MnSi Continuously Cast Billet

Cao Wei, Wang Yu

2007, 28(3): 11-13.

Abstract(29) PDF(1)

Abstract:
The behavior of the inclusion in 20MnSi continuously cast billet is studied by large sample electrolysis, metallographical observation, SEM and EDS etc. The amount, size, distribution, composition and source of the inclusion are investigated. The results show that the unreasonable tundish structure and the unstable casting operation are the mainly causes for the low cleanliness of the billet. This result could be useful to optimize the production technology and improve the quality of 20MnSi continuously cast billet.

Research on Inclusions in Al-killed Steel during LF Refining

Guo Yuming, Xu Zhongbo, Wang Haitao

2007, 28(3): 14-18.

Abstract(19) PDF(1)

Abstract:
To analyze the behaviour of inclusions in Al-killed steel during LF refining and the effect of Ca -treatment, samples were taken at 3 different periods which were 3 minutes after refining, after white slag formation and after Ca-treatment. The number, shape and composition of the non-metallic inclusions were analyzed and contrasted. The results showed that Ca-treatment was effective in improving the cleanliness of steel and modifying the inclusions. Spheroidizing ratio of inclusions increased obviously after white slag formation and increased more after Ca-treatment. Most of inclusions were Al₂O₃-SiO₂-MnO and Al₂O₃ after 3 minutes refining. After white slag formation the inclusions transformed to Al₂O₃-CaO(CaS)-SiO₂, then transformed to Al₂O₃-CaO after Ca-treatment.

Numerical Simulation of Removing Inclusion by Gas Curtain in Continuous Casting Tundish

Gao Aimin, Lin Lei, Ai Liqun

2007, 28(3): 19-23.

Abstract(33) PDF(2)

Abstract:
Gas-liquid-solid three phase flow of the inclusion removing through gas curtain is researched by numerical simulation in the FTSC tundish, whose structure is turbulence inhibitor adding dam. The results show that the gas curtain changes the flow characteristic and improves the inclusion removal, the removal rate of small inclusion with gas curtain control is higher than that with dam control.

Effect of Mo on Microstructure and Property of Fire-resistant Steel

Chen Jie, Pan Fusheng, Zuo Rulin, Li Cong, Dang Ying

2007, 28(3): 24-27.

Abstract(18) PDF(1)

Abstract:
The effect of Mo on the microstructure and property of fire-resistant steel is studied by means of dilatometer and transmission electron microscopy. It is found that the chief effect of Mo in fire-resistant steel is to promote bainite transformation to ensure the high temperature properties, therefore, in view of microstruc-tural controlling, it is possible to reduce Mo content by increasing the content of other elements which can enhance bainite transformation in the design of chemical compositions of fire-resistant steel. The feasibility of designing Mo-reduced and Mo-free fire-resistant steels is discussed.

Morphology of Line Defect on Surface of 304 Stainless Cold Rolled Steel Sheet

Teng Tao, Chen Yinli, Zhao Aimin, Zhou Huan, Wang Shuying

2007, 28(3): 28-32,50.

Abstract(24) PDF(1)

Abstract:
The morphology of line defect on the surface of 304 stainless cold rolled steel sheet is studied. The microscopic morphology of the line defect is investigated by use of optical microscope and scanning electron microscope (SEM) for analyzing the microstructures of the continuously casting slab, hot rolled strip and cold rolled sheet. The microscopic observation indicates the line defect on the surface of 304 stainless cold rolled steel sheet looks like a type of micro "groove", and there is oxide film at the edge of the groove. Some of the oxide film appears multilayer step structure, the oxidation film is made of chromic oxide and ferric oxide, and there are elements such as Mg, Ca, Al etc at the edge.

Influence of Mold Electromagnetic Stirring Structure on Internal Quality of Continuously Cast Bloom

Chen Yong, Yang Subo

2007, 28(3): 42-46.

Abstract(21) PDF(1)

Abstract:
To enhance the metallurgical results of mold electromagnetic stirring (M-EMS) in continuous casting of bloom, experiments for optimizing the structure of M-EMS are carried out. The operation shows that the magnetic induction intensity and bloom internal quality are obviously improved by increasing external diameter and height of mold electromagnetic stirrer, while reducing the internal diameter of the stirrer and raising the coil turns. The magnetic induction intensity is increased from 29.5 mT to 57.2 mT and the ratio of center looseness ≤ 1.0 grade is increased from 90.72% to 96.85%, free center line cracks is increased from 61.56% to 72.65%, and central segregation index of carbon is decreased from 1.10~1.16 to 1.05~1.08.

Influence of Annealing Temperature and Time on Structure and Texture of Cold Rolled Non-oriented Silicon Steel

Luo Laihui, Li Yaohui, Xu Xiangqi

2007, 28(3): 47-50.

Abstract(33) PDF(1)

Abstract:
Considering the annealing technology of cold rolled non-oriented silicon steel, the effects of annealing temperature and time on structure and texture are investigated. The results show that the density of {100} texture drops obviously in the α line and grains get together from {112} < 110 > to {111} < 112 > after annealed. The {100} < hkl > texture increases with the proper lasting of incubation time. The texture distributes homogeneous and the occupancy of {001} texture are improved when the cold rolled non-oriented silicon steel is annealed at 900℃, holding 180 s and then water cooling.

Coupling Analysis of Casting Speed and Tundish Superheat and Controlling Secondary Cooling in Continuous Casting

Ji Zhenping, Liu Wenhong, Xie Zhi, Jia Guanglin, Lai Zhaoyi

2007, 28(3): 51-55.

Abstract(35) PDF(1)

Abstract:
A three-dimensional solidification heat transfer model has been developed to analyze the influence of casting speed and tundish superheat on solidification in continuous casting process. The virtual casting speed and tundish superheat are introduced as feed-forward control variables to determine the secondary cooling water distribution. The simulation results show that this analysis method can eliminate the temperature 'peak' caused by the suddenly changing of speed and temperature. A two-element dynamic cooling water distribution control model based on casting speed and temperature signal of tundish is presented. The application results show that the control strategy is effectual for improving the internal quality of casting billet.

Study on Preparing W-doped Vanadium Dioxide Film by Inorganic Sol-gel Process

Liu Bianmei, Xiong Renjin, Jiang Dongmei, Zhang Huaifa, Yang Weizhong, Zhou Dali

2007, 28(3): 33-36.

Abstract(22) PDF(1)

Abstract:
W-doped vanadium dioxide film was prepared by dipping V-W commixed sol on surface of glass slide and reducing in hydrogen atmosphere. XRD and XPS were used to analyze the phase components of the film. Synthetic conditions of steady V-W commixed sol and W-doped VO₂ film were researched.Results show that the phase transition temperature (T_c) of W-doped Vanadium dioxide film prepared by an inorganic sol-gel process can be reduced to room temperature. At the nearby of phase transition temperature, the resistance and the IR transmission of W-doped vanadium dioxide film have a notable change, and the visible light transmission decreases with the rising of environment temperature.

Research on Direct Reduction of Vanadic Titanomagnetite

Xue Xun

2007, 28(3): 37-41.

Abstract(26) PDF(2)

Abstract:
The direct reduction behaviour of vanadic titanomagnetite is researched in laboratory. The influence of technological parameters on the degree of metallization is discussed, which include reduction temperature, reduction time, atmosphere and the carbon rate. The results show the reduction temperature and atmosphere are the most important influence factors. The degree of metallization can be achieved over 90% steadily at the conditions of temperature being above 1 300℃, over 20 min time and neutral atmosphere or reduction atmosphere. The mineralogy of reduced pallet is analyzed, and the difference of direct reduction behaviour of vanadic titanomagnetite and common iron ore are discussed.

Development and Application of Casting Flux for Bloom Continuous Casting of Medium and Low Carbon Steel

Chen Tianming, Yang Subo, Wen Yongcai, Wang Qian

2007, 28(3): 56-61.

Abstract(26) PDF(1)

Abstract:
Based on the research works of home and abroad, a casting flux was developed according to the bloom continuous casting process of medium and low carbon steel at PZH Steel. The coordination of glasslike-crystal property, capacity of absorbing inclusions and carbon mixing technology of casting flux were researched as key contents in laboratory, a reasonable slag system of casting flux for medium and low carbon steel bloom continuous casting were determined. Industrial-scale experiments showed that the developed casting flux could meet the technological requirements of the bloom continuous casting.

Development of Raw Material for Cold Rolled Ribbed Bar

Su Hezhou, Zhang Weiqiang, Li Jinzhu, Wang Yuan

2007, 28(3): 62-68.

Abstract(16) PDF(1)

Abstract:
With the aim of improving the adaptability of raw material produced for cold rolled ribbed bar, a series of hot rolled rod coil was developed by optimizing the chemical composition and the cooling process of high speed rolling. The rolling yield of cold rolled ribbed bar was increased obviously after using the developed raw material. The influence of chemical composition and ferrite rate as well as crystal grain size on the property of hot rolled rod coil was discussed. The technical measures of improving the adaptability of hot rolled rod coil were put forward.

2007, 28(3): 69-70.

Abstract(23) PDF(1)

Abstract:

2007 Vol. 28, No. 3