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2015年, 第22卷, 第10期 刊出日期:2015-10-15
  

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    Review
  • Song-qin XIA, Zhen WANG, Teng-fei YANG, Yong ZHANG
    中国钢铁期刊网. 2015, 22(10): 879-884.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    As an increasing demand of advanced nuclear fission reactors and fusion facilities, the key requirements for the materials used in advanced nuclear systems should encompass superior high temperature property, good behavior in corrosive environment, and high irradiation resistance, etc. Recently, it was found that some selected high entropy alloys (HEAs) possess excellent mechanical properties at high temperature, high corrosion resistance, and no grain coarsening and self-healing abil-ity under irradiation, especially, the exceptional structural stability and lower irradiation-induced volume swelling, compared with other conventional materials. Thus, HEAs have been considered as the potential nuclear materials used for future fission or fusion reactors, which are designed to operate at higher temperatures and higher radiation doses up to several hundreds of displacement per atom (dpa). An insight into the irradiation behavior of HEAs was given, including fundamental researches to investigate the irradiation-induced phase crystal structure change and volume swelling in HEAs. In summary, a brief overview of the irradiation behavior in HEAs was made and the irradiation-induced structural change in HEAs may be relatively insensi-tive because of their special structures.
  • Metallurgy and Metal Working
  • Jian-hong DONG, Min CHEN, Nan WANG
    中国钢铁期刊网. 2015, 22(10): 885-891.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    A novel-type delivery system consisting of a special feeding device and delivery device was developed and applied to a f600 mm×1 000 mm twin-roll casting system for producing the steel strip of 2 mm in thickness, and the characteristics of fluid flow and temperature field in the casting pool were investigated by mathematical simulation. The results showed that the melt from the novel-type delivery system was distributed to the casting pool along the width direction smoothly and uniformly. At the casting speed of 80 m/min, the difference of minimum residence time (tmin) and actual average residence time (tave) among different ports of the delivery device was less than 0.18 s and 0.26 s respectively, and the average amplitude of level fluctuation was 0.3 mm to 0.6 mm on the free surface of casting pool. In addition, the difference of temperature on the free surface of the pool was below 20 K and the difference across the width direction of roll in different pool depths was less than 13 K, which indicates that the uniformity of temperature distribution was obtained in the casting pool to maintain the casting process and the defect-free steel strip can also be obtained.
  • Guang-ming CAO, Teng-zhi WU, Rong XU, Zhi-feng LI, Fu-xiang WANG, Zhen-yu LIU
    中国钢铁期刊网. 2015, 22(10): 892-896.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    The influences of coiling temperature and cooling condition on structural transformation of the hot-rolled ter-tiary oxide scale formed under continuous cooling conditions were studied by thermal gravimetric analyzer. The fourth oxide scale formed under different conditions were classified and plotted. Because the oxide scale structure transformation is diffusion-controlled and the transformation law is similar to “C” curve, the eutectoid transformation nose temperature is 450 °C. Under condition of low temperature and high cooling rate, ion diffusion behavior is restricted so that the eutectoid reaction is suppressed, resulting in that the fourth oxide scale is mainly made up of pre-eutectoid Fe3O4 and FeO without eu-tectoid products. From scale structure transition diagram, the eutectoid reaction process was affected by coiling temperature and cooling rate, leading to various scale structures.
  • Sheng-fu ZHANG, Liang-ying WEN, Kun WANG, Chong ZOU, Jian XU
    中国钢铁期刊网. 2015, 22(10): 897-904.
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    High-sulfur coal, as an alternative coal source, has a relatively high proportion in coal reserves. However, the feature of high sulfur content, which can cause environmental pollution and poor quality of molten iron, restrains its utilization in coking industry. Coking experiments of high-sulfur coal with Fe2O3, La2O3 and CaO as additives were carried out in order to fix the sulfur in coke. The effects of additives on sulfur distribution, crystallite structure, surface morphology and properties of coke were inves-tigated. The results indicate that CaO can be used as sulfur-fixing agent in coking process, and CaS is the main mineralogical phase of the sulfur-contained mineral constituents in coke. Fe2O3 and La2O3 facilitate the conversion of CaO to CaS. The additives mainly influence the crystallite height and the average interlayer spacing d002 of coke. The addition of La2O3 increases the value of the crys-tallite height while the addition of CaO and Fe2O3 decreases it. CaO leads the pores of coke to increase with its physical action and agglomerating characteristic. Fe2O3 and C can form (Fe,C), resulting in the pulverization and erosion of the pore wall. La2O3 makes the coke surface become more compact and thinner. The reactivity of coke increases with the decrease of crystallite height and crystallite layer number.
  • Guo-hua ZHANG,, Kuo-chih CHOU,
    中国钢铁期刊网. 2015, 22(10): 905-908.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    The deoxidation equilibrium of liquid steel was investigated from a new perspective. Dissolved associate MmOn was used to describe the interaction between dissolved M and dissolved oxygen instead of the interaction parameter of Wagner. The concen-tration of unassociated oxygen could be considered as the activity of oxygen. Or, the percentage of unassociated oxygen in the total dissolved oxygen was the activity coefficient of oxygen. When the content of deoxidizer was low, the dissolved oxygen was mainly composed of the unassociated oxygen, while more and more MxO formed with gradually increasing M content. The present model gave a good description to the aluminum deoxidation equilibrium after considering AlO and Al2O. Furthermore, the higher the con-tent of Al was, the higher the content of Al2O relative to the content of AlO would be.
  • Yousef MOHASSAB, Hong-yong SOHN
    中国钢铁期刊网. 2015, 22(10): 909-915.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    In principle, slag basicity can be expressed as the concentration of free oxygen (O2?) in the slag system. This free oxygen content is equilibrated with different silicate anions in addition to other components in the silicate-based slags. X-ray photon spec-troscopy (XPS) and scanning electron microscope equipped with energy dispersive spectrometer (SEM-EDS) were used to investi-gate the effect of water vapor on the free oxygen content in ironmaking slags. It was found that water in the gas atmosphere plays a significant role in the silicate anion equilibria. Water decreases the amount of free oxygen in the studied slags, with the free oxygen expressed as percentage of the total oxygen decreasing in the order of the following gas mixtures: CO+CO2 (44%, pH2O = 0 kPa) > CO+CO2+H2+H2O (41%, pH2O = 10.13 kPa) > H2+H2O (37%, pH2O = 14.19 kPa). The content of free oxygen ion affects the distribu-tion of elements such as sulfur, phosphorus, and manganese. In addition, it affects the iron oxide content in the slag as well as the interaction between slag and furnace lining.
  • Jagannath PAL, Satadal GHORAI, Debajyoti BANDYOPADHYAY, Sukomal GHOSH
    中国钢铁期刊网. 2015, 22(10): 916-923.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    Lump lime as the most common flux and iron ore as a coolant are used in basic oxygen steel making. However, high melting point, poor dissolution property, fines generation tendency and hygroscopic nature of lump lime often create problems in operation. As the combination of both iron oxide (Fe2O3) and CaO shows eutectic at 1 230 °C, a combined mass of iron oxide and lime melts at lower temperature and dissolves faster in a molten bath. A partially pre-fused synthetic flux (PSF) was prepared through an innovative way in combination of iron oxide fines viz. Linz Donawitz converter sludge and blast furnace flue dust and lime fines by micro-pelletization of the mix followed by coke breeze free sintering. The developed PSF shows good cold handling strength, low melting point (1 180 o), good thermal shock resistance, etc. As a low melting synthetic flux, its performance was as-sessed through dissolution/melting study in hot metal bath and refining of hot metal in a simulated bottom blown converter using (i) PSF, (ii) only lump lime and (iii) lump lime with iron ore when keeping other conditions identical. Very fast dissolution (27–80 s for 1–3 g lumps), enhanced removal of C and P (11–12 min), controlled slag foaming, and reduced oxygen consumption was obtained for using PSF.
  • Material
  • Yong-zheng JIANG, Hua-ping TANG
    中国钢铁期刊网. 2015, 22(10): 924-930.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    The tube rotation method (TRM) refers to the rotational movement of steel tube about its axis as well as translation in rolling direction in stretch reducing rolling process. The influence of the TRM on transverse wall thickness precision of seamless steel tube was studied. Thickness distribution of the TRM was obtained by superimposing the thickened amount of single pass roll-ing. Results show that the TRM can effectively improve the evenness of thickness distribution. In order to analyze the influence mechanism of the TRM, the finite element method was adopted to simulate the thickness distribution in stretch reduction process. Results show that the TRM changes the roundtrip flow between two fix places of conventional stretch reducing and inhibits the directional accumulation of metal. In addition, the TRM has a correction effect on thickness cusp. All these advantages of the TRM help to improve the transverse wall thickness precision of seamless steel tube.
  • Metallurgy and Metal Working
  • Fang PENG, Xiang-huai DONG, Kai LIU, Huan-yang XIE
    中国钢铁期刊网. 2015, 22(10): 931-936.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    The martensitic transformation behavior and mechanical properties of austenitic stainless steel 304 were studied by both experiments and numerical simulation. Room temperature tensile tests were carried out at various strain rates to investigate the effect on volume fraction of martensite, temperature increase and flow stress. The results show that with increasing strain rate, the local temperature increases, which suppresses the transformation of martensite. To take into account the dependence on strain level, strain rate sensitivity and thermal effects, a kinetic model of martensitic transformation was proposed and constitutive modeling on stress-strain response was conducted. The validity of the proposed model has been proved by comparisons between simulation results and experimental ones.
  • Material
  • Xian-bo SHI,, Wei YAN, Wei WANG, Lian-yu ZHAO, Yi-yin SHAN, Ke YANG
    中国钢铁期刊网. 2015, 22(10): 937-942.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    The hydrogen induced cracking (HIC) behavior of a high deformability pipeline steel was investigated with three differ-ent dual-phase microstructures, ferrite and bainite (F+B), ferrite and martensite/austenite islands (F+M/A) and ferrite and martens-ite (F+M), respectively. The HIC test was conducted in hydrogen sulfide (H2S)-saturated solution. The results showed that the steels with F+B and F+M/A dual-phase microstructures had both higher deformability and better HIC resistance, whereas the harder martensite phase in F+M microstructure was responsible for the worst HIC resistance. The band-like hard phase in dual-phase mi-crostructure was believed to lead to increasing susceptibility to HIC.
  • Li-dong WANG, Feng-lei LIU, Qing-yun ZHAO, Hui-bin WU
    中国钢铁期刊网. 2015, 22(10): 943-948.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    In order to investigate the CO2 corrosion behavior and the grooving corrosion susceptibility of electric resistance welded tubes of the Q125 grade, the high temperature and high pressure autoclave was employed to conduct CO2 corrosion experiments for the welded joint. The mechanisms of grooving corrosion and the factors influencing grooving corrosion susceptibility were identified by electrochemical measurement, microstructure observation, residual stress examination, micro-region composition and orientation analysis. The CO2 corrosion results show that the corrosion resistance of the base material is the best, followed by heat-affected zone and the welded seam is the worst. The grooving corrosion occurred in the welded seam, and the grooving corrosion susceptibility of welded seam is relativity high. The dominated reason for the grooving corrosion of the electric resistance welded joint is the notable inclusions consisting of MnS as the main content in the welded seam. The proportion of high-angle grain bound-aries in the welding zone is higher than that of base metal and the heat affected zone, which plays an important role in the corrosion behavior of the welded seam.
  • Chang-gen SHI, Yu WANG, Lin-sheng ZHAO, Hong-bao HOU, Yu-heng GE
    中国钢铁期刊网. 2015, 22(10): 949-953.
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    One-dimensional detonation model and two-dimensional P-M (Prandtl-Meyer) expanding model of double vertical ex-plosive welding were established. A one-dimensional formula of flyer plate velocity was obtained and the bending angle curve rep-resenting flying attitude of flyer plate in double vertical was deduced as well. Compared with single parallel explosive welding, the double vertical explosive welding combines two cladding plates in one explosion. Due to closed charging structure, the influence of rarefaction wave on the plate’s surface in double vertical explosive welding is eliminated and explosion loading time and displace-ment are increased, resulting in the increase of flyer velocity and energy utilization rate by 1.3 times to 1.6 times in different mass ratios. The analysis of microstructure in bonding zone of double vertical cladding plate under traditional charging shows that there is a clear over-melting near the interface, which is in line with the conclusion of detonation mechanism.
  • P. M. AJITH, T. M.AFSAL HUSAIN, P. SATHIYA, S. ARAVINDAN
    中国钢铁期刊网. 2015, 22(10): 954-960.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    The optimum friction welding (FW) parameters of duplex stainless steel (DSS) UNS S32205 joint was determined. The experiment was carried out as the central composite array of 30 experiments. The selected input parameters were friction pressure (F), upset pressure (U), speed (S) and burn-off length (B), and responses were hardness and ultimate tensile strength. To achieve the quality of the welded joint, the ultimate tensile strength and hardness were maximized, and response surface methodology (RSM) was applied to create separate regression equations of tensile strength and hardness. Intelligent optimization technique such as genetic algorithm was used to predict the Pareto optimal solutions. Depending upon the application, preferred suitable welding parameters were selected. It was inferred that the changing hardness and tensile strength of the friction welded joint influenced the upset pressure, friction pressure and speed of rotation.
  • Yong-wei SUN, Ji-zhi CHEN, , Jun LIU
    中国钢铁期刊网. 2015, 22(10): 961-968.
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    High strength bolt steel 0Cr16Ni5Mo was charged with hydrogen by means of electrochemical technique to evaluate the hydrogen diffusion behavior. The bolt steels were investigated by a combination of electrochemical hydrogen permeation, thermal desorption spectroscopy (TDS), slow strain rate test (SSRT) and microstructure observation. The hydrogen concentration of both 10.9 grade (Rm=950—1 150 MPa) and 12.9 grade (Rm=1 150—1 250 MPa) bolt steels increases with increasing the hydrogen charging current densities and charging time. The 12.9 grade bolt steel has higher apparent diffusion coefficient than 10.9 grade steel, corresponding to the value of 4.7×10—7 mm2/s. By means of TDS tests, the activation energies of the two experimental steels are 17.74 kJ/mol and 18.92 kJ/mol, respectively. The hydrogen traps of both grade bolt steels are dislocations and crystal lattice. The notch tensile strength of the steels is reduced with the hydrogen concentration carried out by SSRT. The fracture morphologies of the steels after hydrogen charging present ductile dimple and quasi-cleavage characteristic.
  • Li-xing SUN, Miao-quan LI
    中国钢铁期刊网. 2015, 22(10): 969-976.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    The isothermal compression of M50 steel is carried out on a Gleeble-3500 thermo-mechanical simulator in temperature range of 1 223—1 423 K and strain rates range of 10—70 s—1. The results show that the carbides play a significant role in the flow behavior and microstructure evolution during isothermal compression of M50 steel. The average apparent activation energy for deformation in isothermal compression of M50 steel is (281.1±42.6) kJ.mol—1 at the strains of 0.4—0.8. The dynamic recrystallization of austenite grains occurs in isothermal compression of M50 steel at 1 363 K and 1 393 K, enhancing with the increase of strain rate and/or strain. The volume fraction of the carbides decreases with the increase of deformation temperature during isothermal compression of M50 steel and the fine carbides inhibit the dynamic recrystallization of austenite grain. With the occurrence of dynamic recrystallization, the austenite grains are refined, leading to a minor increase in the flow stress and apparent activation energy for deformation in isothermal compression of M50 steel. The austenite grains begin to coarsen at 1 423 K and dynamic recrystallization is limited. Hot working of M50 steel should not be performed above 1 393 K in order to achieve good workability.