钢铁钒钛

RESEARCH ON MECHANICAL PROPERTIES OF ULTRA-FINE GRAIN STEEL

SONG Li-qiu, HOU Huo-ran, TANG Li, LIU Qing-you, CHENG Xing-de, ZHANG Kai-jian, DONG Han

2003, 24(4): 1-5.

Abstract(55) PDF(1)

Abstract:
Ultra-fine grain hot rolled sheets were produced in 1450 hot mill at PZH Steel, its composition is the same as Q235. The microstructures of ultra-fine grain steel are ferrite and pearlite. Ferrite grain size is about 4 μm. The tensile strength and yield strength of hot rolled sheets are over 510 MPa and 400 MPa respectively. The anisotropy of ultra-fine grain hot rolled sheet is slight. Inclusions are dispersed in steel, so the steel sheet is of good cold-bending property.

TESTING ON PRODUCTION OF VANADIUM-MICROALLOYED HSLA STEEL WITH OVER 550 MPa STRENGTH IN CSP

ZHU Tao, JIANG Chang-lin, HE Yi-zhu

2003, 24(4): 6-13.

Abstract(59) PDF(1)

Abstract:
In order to produce HSLA steel which tensile strength exceeds 550 MPa on CSP line, chemical composition design, CSP continuous-casting simulation, rolling test and Gleeble experiment were carried out. The effect of vanadium-microalloying and controlled rolling & controlled cooling technique was investigated. The production process was drafted and this is the base for further investigating on vanadium-microalloying behavior on CSP line.

EFFECT OF HOT DIP PROCESS ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Ti-IF STEEL SKIN-PASSED GALVANIZED SHEET

ZHENG Zhi-wang, XU Zhe-feng, CHEN Jie

2003, 24(4): 14-19.

Abstract(53) PDF(1)

Abstract:
Effect of hot dip process on the microstructure and mechanical properties of Ti-IF steel skin-passed galvanized sheet are studied on a continuous hot dip galvanizing line. The results show that the ferrite grain has a size of No.10 when the sheet temperature in RTH is below 830℃ and then coarsens gradually as sheet temperature increasing. As a result, the annealing texture of hot dip galvanized sheet changes from mainly {332}and {114}, when the ferrite grain is fine, to the typical {111} as the grain growth, accompanying with the increase of intensity, therefore the r-value increases. However, the r-value will decrease dramatically as the result of randomly distribution of texture when the sheet temperature in RTH exceeds 900℃. Skin-passing reduction has evidently effect on the mechanical properties of final products of Ti-IF steel skin-passed galvanized sheet. As the skin-passing reduction increasing, the yield strength increases obviously, the n-value decreases markedly, and the elongation decreases, but the tensile strength almost remains unchanged. In addition, its effect depends on the ferrite grain size of the final products. The coarser the ferrite grain is, the bigger the effect becomes. Therefore, r-value and n-value are contradictory to each other for skin-passed hot-dip galvanized Ti-IF sheets, and they should be balanced during planning hot-dip processes according to the application demand of customers.

STUDY ON CORROSION RESISTANCE OF JT245 WEATHER-RESISTANT TOWER STRUCTURAL STEEL

XIA Mao-sen, CAI Zhang-ping, LIU Jiang, JIANG Shan-yu, GU Bao-shan, GUAN Xiao-jun

2003, 24(4): 20-24,34.

Abstract(45) PDF(1)

Abstract:
The corrosion resistance of JT245 tower structural steel was tested through interior accelerated corrosion test, electrochemical corrosion test, outside atmospheric corrosion test and surface rusty scale analysis. The results show that the weather resistance of JT245 is as well as CortenA. JT245 steel is an excellent weather-resistant material and could be used to produce tower steel structure. JT245 steel has been applied in the haven and electricity net project, the social effects and economic effects are notable.

RESEARCH ON PRODUCTION OF 300 km/h HEAVY RAIL USING CONTINUOUSLY CAST ROUND BLOOM

CHEN Yong, LI Gui-jun, ZHAO Ke-wen

2003, 24(4): 25-30.

Abstract(53) PDF(2)

Abstract:
The manufacturing process of EF steelmaking→LF refining→VD degassing→round concast has been established, by which rail steel round blooms U71Mn and PD₃ have been successfully produced three times. The inspection of round bloom quality suggests that the surface defect-free achieves 100% of total rounds produced from continuous casting. Meanwhile, center looseness is ≤ 1.0, shrinkage cavity is ≤ 0.5, central segregation index of carbon is ≤ 1.07, and the ratio of equiaxed crystal zone is ≥ 40%. The internal quality and mechanical property of experimental rails produced from continuously cast rounds could meet the requirement of 300 km/h high-speed tracks.

EFFECT OF MICROALLOY ELEMENT Cr ON MICROSTRUCTURE AND PROPERTIES OF HIGH-CARBON STEEL WIRE

FENG Yun-li, YANG Hai-li

2003, 24(4): 31-34.

Abstract(46) PDF(1)

Abstract:
The effect of microalloying element Cr on microstructure and mechanical properties of high-carbon steel wire and the reasonable content of Cr in steel were investigated. The results show that the microstructure of steel is optimized with the Cr added,the content of pre-eutectoid ferrite in metallographic structure reduce,the content of sorbite increase,and the tensile strength of wire increase 75~100 MPa. The comprehensive performance of high-carbon steel wire is improved and the reasonable content of Cr is within the range of 0.18%~0.24%.

EXPERIMENTAL INVESTIGATION ON DISSOLVING OXYGEN IN HOT METAL PRETREATMENT

WU Bao-guo, LI Chun-lin, DONG Yuan-chi, WANG Shi-jun

2003, 24(4): 35-38.

Abstract(31) PDF(1)

Abstract:
The changing law of oxygen potential was studied during hot metal pretreatment by using Fe₂O₃-CaO-CaF₂ and Na₂CO₃-Na₂SO₄ fluxes under the laboratory conditions. At the same time, the suitable range of oxygen potential for removing phosphorus and sulfur simultaneously was discussed. The results show that the oxygen potential in iron melt during dephosphorization can be reached to 5.911×10^-6~10.03×10^-6 in 5 min and then changes only in a narrow range. The final [P] content of 0.008%~0.012% and sulphur content of 0.003%~0.007% can be obtained at 1 623 K if the oxygen potential is controlled in the range 3.0×10^-6~6.5×10^-6.

CONTROLLING OF INCLUSION MORPHOLOGY IN STEEL CORD BY COMPOSITE REFINING SLAG

ZHANG Jun, WANG Yong, LI Ben-hai, XU Xiao-dong

2003, 24(4): 39-43.

Abstract(51) PDF(1)

Abstract:
The inclusion morphology is controlled by changing slag formation and reducing the added quantity of Al and bauxite in refining process. The results demonstrate that the most effective method to control the inclusion morphology is adding wollastonite or the mixture of wollastonite in refining process of steel cord. The cleanliness of molten steel has been greatly improved after adopting new slag refining process.

EFFECT OF LADLE REFINING TECHNIQUE ON YIELDING RATE OF VN ALLOY

ZHANG Chen

2003, 24(4): 44-48.

Abstract(70) PDF(3)

Abstract:
The effect of ladle refining parameters on yielding rate of N and V of VN alloy was studied. The results show that the temperature, composition of steel and the slag quantity have no effects on the yielding rate. Oxygen-potential is the key factor, and its regressive relationship with the yielding rate of N was obtained. Although the final yielding rate of V and N isn't affected by adding Al₂O₃ and CaF₂ in slag, the velocity of VN alloy entering steel is delayed greatly. The yielding rate of V can stably keep higher than 95% under normal conditions, but V will be oxidized gradually if the oxygen content is higher than 0.01%.

RESEARCH ON INCREASING TiO₂ RECOVERY PERCENT ON MAIN MANUFACTURING PROCESS AT TITANIUM RECOVERY PLANT OF PZH STEEL

CENG Li-guo

2003, 24(4): 49-54.

Abstract(44) PDF(1)

Abstract:
According to the situation of total TiO₂ recovery percent being lower 21% in the main manufacturing process (coarse ore dressing) and tiny ore manufacturing process (tiny ore dressing) at Titanium Recovery Plant of PZH Steel, the effect of magnetic mineral on TiO₂ recovery percent from gravity concentrate was investigated. The choice of suitable iron removal position and equipment was discussed. The measures of increasing TiO₂ recovery percent on main manufacturing process are put forward considering the iron removal.

RESEARCH ON WEATHERABILITY OF NANO-TiO₂ MODIFYING EXTERIOR LATEX PAINT

WU Jian-chun, HUANG Wan-xia, ZHENG Hong-ping, CAO Jian-jun

2003, 24(4): 55-58.

Abstract(65) PDF(1)

Abstract:
Employing ultrasonic dispersing technology makes nano-TiO₂ powder into normal latex paint to manufacture nano-TiO₂ modifying latex paint. The experiments show that the ageing resistance and weatherability of latex paint is evidently improved as nano-TiO₂ powders being dispersed into.

TESTING AND ANALYSING FOR DUCTILE-BRITTLE TRANSITION TEMPERATURE OF HRB400 ANTI-SEISMIC STEEL BAR

QIN Bin, SHENG Guang-min, GONG Shi-hong

2003, 24(4): 59-63.

Abstract(54) PDF(1)

Abstract:
Series of impact test for HRB400 anti-seismic steel bars with diameters of Ø25 mm and Ø32 mm dedicate the ductile-brittle transition temperature of big size steel bars are higher than small ones. Light microscope observation reveals the Ø32 mm steel bar has coarse grain, SEM show brittle fracture take place at 12℃. TEM was used to analyze the form and distribution of vanadium, then vanadium-nitrogen alloying and controlled rolling was brought forward as a suggest to enhance the impact property of HRB400 steel bars at low temperature.

INFLUENCE OF CONTAINING Ba DEOXIDIZER ON QUALITY OF STEEL STRIP

ZHENG Wen-guang, GUO Dian-feng, ZHAO Dian-qing, ZHANG Xiao-guang

2003, 24(4): 64-66.

Abstract(48) PDF(1)

Abstract:
The influence of two different deoxidizer BaCaAlSi and SiC on quality of steel strip were investigated by contrasting the deoxidizing practice of BaCaAlSi and SiC in steel tapping. The T[O] is 14.8×10^-6 and 17.8×10^-6 respectively, [N] is 48.6×10^-6 and 53×10^-6 respectively in steel strip when adopting BaCaAlSi and SiC as deoxidizer. The results show that the inner quality of finial strip is better using BaCaAlSi than using SiC.

INFLUENCE OF ALLOYING ELEMENT TITANIUM ON FORMATION OF D-TYPE GRAPHITE

LI Xiao-ping, ZHONG Yuan-long, LIN Yuan-zu

2003, 24(4): 67-70.

Abstract(54) PDF(2)

Abstract:
The influence of alloying element Ti on the formation of D-type graphite was analyzed from two aspects. Ti promotes the precipitation of primary austenitic dendrite, affects the morphology of the austenitic dendrite, and creates the avail condition for nucleation and growth of D-type graphite. The influence of titanium on nucleation and growth of graphite is connected to its content. When the content of Ti > 0.1%, it will primarily holdback graphitizing, and is helpful to the formation of D-type graphite.

2003 Vol. 24, No. 4