2006年, 第1卷, 第4期　刊出日期：2006-08-15

  

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Abstracts
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  Modeling of Incubation Time for Austenite to Ferrite Phase Transformation

  ZHOU Xiao-guang;LIU Zhen-yu;WU Di;WANG Wei;JIAO Si-hai

  中国钢铁期刊网. 2006, 1(4): 0-0.

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  On the basis of the classical nucleation theory, a new model of incubation time for austenite to ferrite transformation has been developed, in which the effect of deformation on austenite has been taken into consideration. To prove the precision of modeling, ferrite transformation starting temperature (Ar3) has been calculated using the Scheil’s additivity rule, and the Ar3 values were measured using a Gleeble 1500 thermomechanical simulator. The Ar3 values provided by the modeling method coincide with the measured ones, indicating that the model is precise in predicting the incubation times of austenite to ferrite transformation in hot deformed steels.
Review
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  Indirect Methods to Detect and Evaluate Inclusions in Steel  A Review

  ZHANG Li-feng

  中国钢铁期刊网. 2006, 1(4): 0-0.

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  Indirect methods to detect and evaluate inclusions in steel are extensively reviewed, including total oxygen measurement, nitrogen pickup, steel and slag composition measurement, lining refractory observation, tracer studies to determine exogenous inclusions from slag and lining erosion, SEN clogging and final product tests. There is no single ideal method to detect and evaluate inclusions in steel, so it is best to couple several methods together to give a more accurate evaluation. Total oxygen content and nitrogen pickup in low carbon aluminum-killed steel as criterion of clean steel in many plants are summarized.
Material
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  Giant Stress-Impedance Effect in Co71.8Fe4.9Nb0.8Si7.5B15 Amorphous Glass-Covered Wires

  CHEN Zheng;;LI De-ren;;LU Zhi-chao;;ZHOU Shao-xiong;

  中国钢铁期刊网. 2006, 1(4): 0-0.

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  The giant stress-impedance (GSI) effect in as-cast and DC current annealed Co71.8Fe4.9Nb0.8Si7.5B15 amorphous glass-covered wires is presented. The SI ratio of the as-cast sample exhibits negative GSI effect. For the sample annealed by 60 mA DC current, the SI ratio first increases with applied tensile stress, then decreases with the applied tensile stress. The maximum ΔZ/Z ratio of 304% is obtained. Frequency dependence in the range from 1 to 110 MHz of the GSI effect is investigated. Experimental results show that the real part R and the imaginary part X of impedance play an important role at high frequency and low frequency, respectively. At 1 MHz, the maximum ΔX/X of 1 448% is obtained. At 110 MHz, the maximum ΔR/R ratio of 648% is obtained.
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  Superplasticity of Directionally Solidified NiAl-15Cr Alloy at High Temperature

  ZHANG Guang-ye;;ZHANG Hua;ZHANG Hou-an;WU Xian-ming;GUO Jian-ting

  中国钢铁期刊网. 2006, 1(4): 0-0.

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  Ni-25Al-15Cr (atomic percent, %) alloy was directionally solidified (DS) under argon atmosphere in an Al2O3-SiO2 ceramic mold by standard Bridgman method. The microstructure of the as-fabricated alloy was studied using optical microscope, X-ray diffractometer, and scanning electron microscope. The alloy consisting of dendritic -NiAl phase, interdendritic  phase, and transient layer  phase, has been investigated. This alloy exhibits superplastic deformation behavior at 1 273−1 373 K over an initial strain rate range of 8.35×10-4−1.67×10-2 s-1. The maximum elongation of 280% with strain rate sensitivity index m=0.22 was obtained at the temperature of 1 323 K and an initial strain rate of 8.35×10-3 s-1. Transmission electron microscopy (TEM) observations indicate that the superplastic deformation stems from the balance between high resistance (by dislocation sliding) and strain softening (by dynamic recovery and recrystallization).
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  Interfacial Microstructure of Al-Sn-Pb Alloy/Steel During Liquid-Solid Bond Rolling

  XU Guang-ming;LI Bao-mian;CUI Jian-zhong

  中国钢铁期刊网. 2006, 1(4): 0-0.

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  Studies were conducted on the interfacial microstructure of a steel/liquid aluminium and its evolution during the bonding rolling process. The effects of wetting time and rolling deformation on the diffusion layer and on the bonding strength were examined. By means of electron microscopy and electron probe analysis, it was found that the diffusion layer is mainly composed of FeAl3. For a steel temperature of 250 ℃ and an aluminium temperature of 850 ℃, the diffusion layer was formed within 3 s, and the shear strength of the samples increased after 8 to 14 s. Although the interface was not damaged, it was deformed notably. For an aluminium temperature of 750 ℃ and a wetting time of 11 to 17 s, the shear strength of the interface remained high, but the interface was obviously broken during rolling, leading to reduced bonding strength.
Metallurgy
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  Anticorrosion Performance of Carbon Steel in 55%LiBr Solution Containing PMA/SbBr3 Inhibitor

  HU Xian-qi;LIANG Cheng-hao;HUANG Nai-bao;

  中国钢铁期刊网. 2006, 1(4): 0-0.

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  The anticorrosion performance of carbon steel in 55%LiBr solution containing PMA/SbBr3 inhibitor was studied by weight-loss tests, electrochemical measurements and surface analysis. In 55%LiBr+PMA/SbBr3 solution, corrosion rates of carbon steel at 145 ℃, 175 ℃, 190 ℃ and 240 ℃ are 18.32 μm•a-1, 27.68 μm•a-1, 53.58 μm•a-1 and 73.78 μm•a-1, respectively. PMA/SbBr3 inhibitor may inhibit the corrosion of carbon steel in 55%LiBr solution effectively. Especially, it shows an excellent corrosion inhibition performance agent at high temperature. Both anodic and cathodic reactions of carbon steel may be inhibited by PMA/SbBr3 inhibitor, and so it may be classified as mixed inhibitor. In 55%LiBr+PMA/SbBr3 solution, the apparent activation energy of the corrosion reaction of carbon steel is 29.61 kJ•mol-1. The corrosion inhibition mechanism of PMA/SbBr3 is suggested as follows: PMA has the effect of inhibiting hydrogen producing and a strong oxidizing property; Sb3+ also exhibits oxidizing properties, and can exist stably with PMA in LiBr solutions; the passive film comprising Fe2O3 and antimony formed on carbon steel surface may prevent bromine- from diffusing into the metal surface due to the synergistic effect of PMA and Sb3+; As a result, the anticorrosion performance of carbon steel may be improved by PMA/SbBr3 inhibitor in 55% LiBr solution.
Material
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  Comparative Study on Constitutive Modeling of Tantalum and Tantalum Tungsten Alloy

  ZHOU Jian-qiu;Akhtar S. Khan;CAI Rui;CHEN Ling

  中国钢铁期刊网. 2006, 1(4): 0-0.

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  As a model bcc metal, tantalum and its alloys have wide applications in defense-related fields. The KHL (Khan, Huang, Liang, 1999) model and the constitutive model proposed by Nemat-Nasser et al (Nemat-Nasser and Kapoor, 2001) for tantalum and its alloys were analyzed and compared with each other. A set of published data recorded during elastic-plastic deformations of tantalum, tantalum alloy containing tungsten of 2.5% (Ta-2.5W), over a wide range of strains, strain rates, and temperatures were used to correlate the two models. Overall, it can be concluded that KHL model correlates much better with the data than the model used by Nemat-Nasser et al.