钢铁钒钛

RESEARCH ADVANCE OF NANO TITANIUM DIOXIDE AND ITS APPLICATION IN FUNCTIONAL MODIFICATION OF PLASTICS

CAO Jian-jun

2004, 25(4): 1-8.

Abstract(38) PDF(0)

Abstract:
The synthetic methods of nano-titanium dioxide are reviewed, which includes prepare methods of gas phase and liquid phase. The surface modification technologies of nano-TiO₂ particles, including inorganic coating and organic modification, are summarized. The physico-chemical properties and application fields of nano-TiO₂ are introduced in brief. The research advance of nano-TiO₂ in functional modification of plastics is reviewed in particularly, such as aging resistance composites, antibacterial composites and so on. Furthermore, the action mechanisms of nano TiO₂ in aging resistance and antibacterial are emphatically discussed.

INFLUENCE FACTORS AND IMPROVING MEASURES ON APPLICATION PERFORMANCE OF TiO₂

LI Qin, HU Hong-fei, WU Liang-ying, HOU Sheng-dong, CHEN De-ming, WEI Chang

2004, 25(4): 9-14,28.

Abstract(35) PDF(1)

Abstract:
The influence factors of application performance, which includes hiding power, durability, dispersivity and so on, for titanium dioxide are discussed. The ways of coating silica and alumina on rutile titanium dioxide are explained, and the effects of the coating way on the application performance are emphatically discussed. The principle of the coating and the main problems in coating technologies are introduced, and the solving measures for the problems are put forward.

DEVELOPING TREND OF GALVANNEALED AUTO SHEET STEELS

ZHANG Li-yang, LI Jun, ZUO Liang

2004, 25(4): 15-19.

Abstract(36) PDF(0)

Abstract:
The present development situation of galvannealed automobile sheet steel at home and abroad was introduced. For galvannealed IF steel, traditional strengthening method and new strengthening technology were introduced, and it was pointed out that galvannealed IF steel is developing to high strength when maintaining good formability. The developing situation of 340 MPa galvannealed bake-hardening steel was introduced in detail. It was pointed out that this steel was developing to good formability, good powdering resistance and good anti-aging. Galvannealed low-carbon equivalent type high-strength steel and dual-phase steel were introduced, too. And they are developing to good formability. Furthermore, the present developing situation of galvannealed TRIP steel were introduced too. It was put forward that galvannealed sheet steel, especially high-strength galvannealed sheet steel, for automobile should be paid attention in China.

OPTIMIZATION OF MOLD COOLING PROCESS AT BLOOM CONTINUOUS CASTING

CHEN Yong, ZHANG Da-de, YANG Su-bo, LI Gui-jun, LI Jian-quan

2004, 25(4): 20-23.

Abstract(62) PDF(0)

Abstract:
The existing cooling ability of bloom continuous casting mold at PZH Steel was evaluated, then, the mold cooling process was optimized. The practical operation shows that the solidified shell of molten steel at the exit of mold is increased from 14.5~15.0mm to 19.0~20.5mm by enhancing cooling intensity in mold, while, the solidified shell thickness is more uniform with adjusted the mold water flow distribution to balance the heat removal between wide and narrow plates, and the longitudinal corner crack is obviously reduced.

DEVELOPMENT AND APPLICATION PERFORMANCE OF Al-AlN-Al₂O₃ MULTIPHASE SLIDE PLATE

BU Jing-long, YU Zhi-dong, YANG Xiao-chun, WANG Zhi-fa, WANG Rui-sheng, WANG Rong-lin

2004, 25(4): 24-28.

Abstract(54) PDF(1)

Abstract:
Using 80%~90% tabular corundum and 10%~20% Al as the main material, a multiphase Al-AlN-Al₂O₃ material whose main crystalline phase is corundum and the bond phases are Al and AlN can be prepared by nitridation-sintering at 1 100 ℃ and surface oxidation treatment under 800 ℃. Made multiphase Al-AlN-Al₂O₃ of sliding gate of steel ladle, obtained excellent application effect. The experiments show that the slide plate is of compact structure because of the molten Al fill in the gaps of corundum grains and the bulk expansion with the formation of AlN and Al₂O₃. The Al-AlN-Al₂O₃ multiphase slide plate has excellent corrosion resistance and thermal shock resistance, so its service life is two times longer than that of Al₂O₃-C slide plate.

EFFECT OF VANADIUM ON GRAIN REFINEMENT WITH LARGE DEFORMATION AT LOWER TEMPERATURE

ZHANG Kai-hua

2004, 25(4): 29-32,36.

Abstract(74) PDF(2)

Abstract:
The mechanical properties and grain sizes of low carbon steel with different vanadium content were tested under large deformation. The results show that vanadium has no effect on grain refinement when rolled at higher temperature, but when rolled at lower temperature, vanadium can refine ferrite grain and enhance the yield strength and the tensile strength of low carbon steel.

STUDY ON 60 kg GRADE FIRE-RESISTANT STEEL WITH LOW YIELD RATE

HU Shu-e, SUN Wei-hua, LIU Xiao-mei, LI Long, DING Hua

2004, 25(4): 33-36.

Abstract(59) PDF(0)

Abstract:
A fire-resistant steel with low yield rate was tested, and the chemical compositions, experimental parameters, mechanical properties of the steel were presented. The effect of alloying elements and microstructure on the yield rate and high temperature strength was discussed in detail. Testing results show that the experimental steel have excellent comprehensive mechanical properties, low yield rate with ferrite matrix and bainite. The high temperature strength of steel increases as adding alloying-element Cr、Mo、Nb etc.

RESEARCH ON HIGH TEMPERATURE PLASTICITY OF X70 PIPELINE STEEL IN CONTINUOUS CASTING

ZHANG Chen

2004, 25(4): 37-41.

Abstract(44) PDF(3)

Abstract:
Tensile testing for X70 pipeline steels in 600~1 350 ℃ was carried out, and the fracture micrographs of samples in different temperature were examined with SEM and metallographic microscope. The effects of C, N content on area reduction (RA) were examined. The results show 700~900 ℃ is the embrittlement region III, where the RA is lower than 40%. The plasticity decreases in 1 000~1 250 ℃ with the increase of C and N, while the plasticity is improved slightly in region III. It's the contribution of pinning function of carbonitride of Nb, V precipitated in grain boundary.

STUDY ON HYDRATION CHARACTERISTICS OF GROUNDED HIGH TITANIUM SLAG

AO Jin-qing

2004, 25(4): 42-46.

Abstract(49) PDF(1)

Abstract:
The characteristics of grounded high titanium slag during the hydration process were discussed comparing with grounded low titanium one. The mineral composition, hydability and hydrating characteristics of grounded high titanium slag, and the hydration product were analyzed by means of X-ray diffraction analysis, SEM, EMPA, DTA separately. The results demonstrate that the hydaulic activation index of high titanium BF slag is 77.4% while that of slag with low titanium is 108%. The high titanium slag has the same hydration product as the low titanium slag and the portland cement. However, the amount and the crystallinity of hydration product in the high titanium BF slag are obviously lower than that in the low titanium slag. This means the high titanium slag has low hydaulic activation index.

ANALYSIS ON HORIZONTAL CRACKING OF RAIL FLASH WELDING JOINT

LI Da-dong

2004, 25(4): 47-52.

Abstract(61) PDF(0)

Abstract:
The cracking fractures of U75V rail flash welding joint were inspected using metallographic microscope and SEM. A lot of dimples wood grain area was found in crack source, and the cracks expanded from the other side of rail to weld and stopped at weld. The decarbonization on surface of the cracks confirm the cracks generate in high temperature period of weld,so it is welding hot crack.

INFLUENCE OF STRUCTURAL PARAMETERS ON STEADY STATE HIGHEST TEMPERATURE AND THERMAL STRESS OF BF COOLING STAVE

DENG Kai, WU Li-jun, CHENG Hui-er, QIAN Zhong

2004, 25(4): 53-58.

Abstract(63) PDF(0)

Abstract:
The process of steady-state heat transfer of blast furnace stave and the influence of different structural parameters(diameter and shape of cooling water pipes, space between cooling water pipes, thickness of stave and cast-in bricks) on the steady-state highest temperature and thermal stress of stave were numerically simulated and analyzed by engineering software ANSYS. This provides important theoretical basis for the structural design of cooling stave.

NUMERICAL SIMULATION OF TEMPERATURE FIELD AND STRESS FIELD FOR COLD ROLLED COIL IN BELL TYPE ANNEALING

LI Jun-hong, ZHOU Dan, FENG Kai-rong, ZHOU Yi-lin

2004, 25(4): 59-63.

Abstract(55) PDF(0)

Abstract:
The temperature and thermal stresses are important parameters in the process of bell type annealing. The computational models of the temperature fields and stresses fields in the bell type annealing process were established by the methods of the finite difference method and the finite element method. The change event of temperature and thermal stresses in coils are quantitatively analyzed and compared with the measured results. The distribution regularities of temperature and thermal stresses in the process of bell type annealing are arrived at. This work could be a guidance for the optimization of annealing practice.

FINITE ELEMENT ANALYSIS ON TEMPERATURE FIELD OF BOF SHELL UNDER HI-VAP COOLING

MA Xue-dong, MENG Hui-rong, GAO Xing-qi, FAN Xun

2004, 25(4): 64-68.

Abstract(41) PDF(0)

Abstract:
After the magnesium-carbon bricks were used as BOF lining, the temperature of BOF shell went up greatly, and led the BOF shell to creep. By means of Hi-Vap cooling technology, the temperature of BOF shell could be controlled. Based on the FEM, and making use of ANSYS software package, the temperature field of BOF shell was analyzed under complicated working state for a large complicated structure and complex heat transfer status and Hi-Vap cooling etc. The cooling parameters were rationally fixed on, such as cooling time and water flow etc. These achieved the purpose of restraining creeping and provide a base for the cooling system design as well as the maintaining technology of BOF body.

2004 Vol. 25, No. 4