LIU Yan
,
JIANG Mao-fa
,
XU Li-xian
,
WANG De-yong
钢铁研究学报(英文版)
For describing and resolving the process of chromium ore smelting reduction in a converter preferably, the coupling dynamic model was established based on the kinetic models of chromium ore dissolution and interfacial reducing reaction between the slag and metal. When 150 t stainless steel crude melts with chromium of 12% are produced in a smelting reduction converter with no initial chromium in metal at 1560 ℃, the results of the coupling dynamic model show that the mean reduction rate and injection rate of chromium ore are 0091 %·min-1 and 467 kg·min-1, respectively. The foundation of the coupling dynamic model provides a reference and basis on the constitution of rational processing route for a practical stainless steelmaking.
关键词:
coupling dynamic model
,
smelting reduction
,
stainless steel crude melt
,
converter
MIN Yi
,
JIANG Mao-fa
钢铁研究学报(英文版)
In this paper, exergy analysis was applied to the ladle furnace refining process of modern clean steelmaking. Results showed that, exergy loss induced by unavailable electric energy is the largest, and the electric energy efficiency is 46.20%. To cut down the unavailable electric energy, industrial experiments of submerged arc heating were carried out combined with slag composition modification. Results showed that, submerged arc heating can be achieved within most heating period, average heating rate increased by 0.5℃•min-1, unavailable electric energy decreased by 21.730 MJ per ton steel, and electric energy efficiency enhanced by 14.84%.
关键词:
LF (ladle furnace);exergy analysis;exergy loss;submerged arc heating
QU Tian-peng
,
LIU Cheng-jun
,
JIANG Mao-fa
钢铁研究学报(英文版)
The fluid flow in tundish is a non-isothermal process and the temperature variation of stream from teeming ladle dominates the fluid flow and thermal distribution in tundish. A numerical model was established to investigate the effect of inlet cooling rate on fluid flow and temperature distribution in tundish based on a FTSC (Flexible Thin Slab Casting) tundish. The inlet cooling rate varies from 0.5 to 0.25 ℃/min. Under the present calculation conditions, the following conclusions were made. When the stream temperature from teeming ladle drops seriously (for inlet cooling rate of 0.5 ℃/min), there is a “backward flow” at the coming end of casting. The horizontal flow along the free surface turns to flow along the bottom of tundish. The bottom flow shortens the fluid flow route in tundish and deteriorates the removal effect of nonmetallic inclusions from molten steel. Nevertheless, when the inlet cooling rate decreases to 0.25 ℃/min, the horizontal flow is sustained during the whole casting period. The present research provides theoretical directions for temperature control in teeming ladle and continuous casting tundish during production of advanced steels.
关键词:
tundish
,
thermal distribution
,
unsteady
,
numerical simulation
LIU Cheng-jun
,
HUANG Ya-he
,
JIANG Mao-fa
钢铁研究学报(英文版)
Clean high carbon heavy rail steel was prepared by the process of vacuum induction furnace smelting, forging and rolling. Mechanisms of RE on the impact toughness and fracture toughness for clean high carbon steel were investigated. In addition, the appropriate range of RE content for clean high carbon steel was determined. Both the austenite grain size and pearlite lamellar spacing decreased due to small amount of RE, consequently the impact toughness and fracture toughness were improved evidently. When the RE content exceeded a critical value, the pearlite lamellar spacing was increased, because RE was segregated on the austenite grain boundaries, damaged the orientation relationship of pearlite transformation, caused the disorder growth and morphology degenerating of pearlite. With the increasing of RE content, both the impact toughness and fracture toughness of clean high carbon steel were gradually increased at first and then decreased. It was found that when the RE content was between 00081% and 00088%, both the impact toughness and fracture toughness of clean high carbon heavy rail steel were the best. The maximum ballistic work was 212 J (20 ℃) and 122 J (-20 ℃), respectively. The maximum plane-strain fracture toughness was 4567 MPa·m1/2 (20 ℃) and 3704 MPa·m1/2 (-20 ℃), respectively.
关键词:
rare earth
,
high carbon steel
,
heavy rail steel
,
clean steel
,
impact toughness
,
fracture toughness
李尊
,
吴谨
,
刘劲
,
吴秋红
液晶与显示
doi:10.3788/YJYXS20153002.0353
在经典 Criminisi 图像修复算法框架的基础上，针对优先权可靠性低和全局搜索最佳模板效率低、错误匹配率大的缺点进行改进。改进的算法为基于萤火虫算法(FA)的快速 Criminisi 图像修复算法。首先从数学的角度引入正规化函数至置信度，以此提升优先权计算的可靠性；然后引入 FA 到最佳模板的搜索与填充中，能够有效地将全局搜索与局部搜索有效地结合，鲁棒性较高，提高效率且错误匹配率低。实验结果表明：采用本文的改进算法能在保证修复质量的基础上降低时耗，提高效率。
关键词:
Criminisi算法
,
优先权
,
最佳匹配模板
,
FA
Applied Surface Science
A novel kind of micro-arc oxidation (MAO) coating was prepared on magnesium alloy surface coated with rare earth conversion film (RE-film) in an alkaline aluminum oxidation electrolyte by AC power source. Inspection of scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) microspectroscopy, the structure and composition of MAO coating formed on AZ91D with RE-film under different applied voltages were investigated and the performance of the optimized MAO coating compared with the MAO coating directly formed on magnesium alloy. As the pretreatment of magnesium alloy with RE-film, the cerium oxides can be incorporated into the MAO coatings, reduce porosity of the MAO coating surface and enhance the thickness of MAO coating. These structure features and the cerium oxides incorporated into the MAO coating result in greatly improved corrosion resistance. Base on electrochemistry impedance spectroscopy (EIS) measurement, the electronic structure and composition analysis of the MAO coating, a double-layer structure, with a compact inner layer and a porous outer layer, of the coating was proposed for understanding its corrosion process. (C) 2010 Elsevier B.V. All rights reserved.
关键词:
Magnesium alloy;Rare earth conversion film;Micro-arc oxidation;Porosity;az31 magnesium alloys;micro-arc oxidation;mg-al alloys;electrolyte;resistance;cerium;phosphate
Science China-Technological Sciences
Product/metal ratio (PMR) was introduced as a novel criterion for the evaluation of electrolytes on micro-arc oxidation (MAO) of Mg and its alloys. The criterion initially sprang from Pilling-Bedworth ratio (PBR), focused on the roles of electrolytes for the compactness of the fabricated coatings, and took attention on properties of reactants/products during MAO. Meanwhile, based on our experiments as well as the results from literatures, the effects of electrolyte additives on morphologies and compositions of the fabricated MAO coatings of Mg alloys were exploited for verification and supplement of the initial criterion. In combination of the initial PMR criterion and experimental verification, PMR could be represented by special mode (PMR (s)=V (oxide products)/V (alloy substrates)) and general mode (PMR (g)= PMR (s)+ PMR (d)). The ideal PMR (s) should be between 1 and 2, while PMR (d) is related to the coating deposition during MAO. PMR (d) is a supplement to PMR (s) when the effect of the overlaying property (O) of the coatings and the effective deposition (D) of electrolyte composites are considered (PMR (d)=f(O, D). O is related to the melting point (MP) and boiling point (BP) of the MAO products. D is related to the effective reactions between alloy substrates and electrolytes during MAO.
关键词:
micro-arc oxidation;Mg alloys;Pilling-Bedworth ratio;product/metal;ratio;az91d magnesium alloy;electrochemical corrosion behavior;silicate-containing electrolytes;ceramic coatings;potassium fluoride;resistance;films;surface;microstructure;technology
周筠
,
吴勇生
,
李如燕
,
孙可伟
,
王敏
硅酸盐通报
以粉煤灰(FA)、铸造旧砂热法再生粉尘(DHRS)为原料,在水玻璃型碱性激发液的激发作用下研究制备了DHRS-FA地质聚合物材料(铸造旧砂热法再生粉尘-粉煤灰基地质聚合物材料).为了探讨不同的养护工艺对DHRS-FA地质聚合物材料强度的影响,研究了自然养护、湿养养护、高温蒸养(40℃、60℃、80℃)养护对地质聚合物强度的影响.结果表明:试样在高温养护工艺下,其早期抗压强度形成较快,且优于自然养护和湿养养护工艺下试样形成的抗压强度;试样在高温养护工艺下,中期和后期抗压强度趋于自然养护试样的抗压强度;而湿养条件下养护的试样抗压强度最差.
关键词:
粉煤灰
,
铸造旧砂热法再生粉尘
,
地质聚合物材料
,
高温养护工艺
Electrochimica Acta
Protective composite coatings were prepared on magnesium alloy AZ91D by micro-arc oxidation (MAO) treatment plus a top coating with sealing agent using multi-immersion technique under low-pressure conditions. The corrosion resistance of AZ91D alloy with composite coatings was superior evidently to that with merely MAO film. SEM observations revealed that the sealing agent was integrated with MAO film by physically interlocking; therewith covered uniformly the surface as well as penetrated into pores and rnicro-cracks of MAO film. The anti-corrosion properties in 3.5% NaCl solution of the composite coatings were evaluated by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Based on the results of chronopotentiometric (E similar to t) and EIS measurements for long time immersion in 3.5% NaCl solution, appropriate equivalent circuits for the composite coatings system were proposed. It follows that due to the blocking effect of the sealing agent in pores and cracks in MAO film, the composite coatings can suppress the corrosion process by holding back the transfer or diffusion of electrolyte and corrosion products between the composite coatings and solution during immersion. (c) 2005 Elsevier Ltd. All rights reserved.
关键词:
composite coatings;MAO film;sealing;magnesium alloy AZ91D;EIS;micro-arc oxidation;impedance spectroscopy;interfacial factors;phosphate coatings;alkaline-solutions;aluminum-alloys;nacl solution;anodic films;mg alloys;part 2
