材料期刊网

Effect of Sulfate Reduced Bacterium on Corrosion Behavior of 10CrMoAl Steel

WANG Hua , LIANG Chenghao

钢铁研究学报(英文版)

The effects of sulfate reduced bacterium (SRB) on the corrosion behavior of 10CrMoAl steel in seawater were studied by chemical immersion, potentiodynamic polarization, electrochemical impedance spectroscopy measurement, and scanning electron microscope techniques. The results show that the content of element sulfur in the corrosion product of 10CrMoAl steel in seawater with SRB is up to 923%, which is higher than that of the same in sterile seawater. Xray diffraction demonstrates that the main corrosion product is FeS. SRB increases the corrosion rate by anodic depolarization of the metabolized sulfide product. SEM observation indicates that the corrosion product is not distributed continuously; in addition, bacilliform sulfatereduced bacterium accumulates on the local surface of 10CrMoAl steel. Hence, SRB enhances sensitivity to the localized corrosion of 10CrMoAl steel in seawater.

关键词: sulfate reduced bacterium;10CrMoAl steel;localized corrosion

Resistance Switching Properties of Ag/ZnMn2O4/p-Si Fabricated by Magnetron Sputtering for Resistance Random Access Memory

WANG Hua , LI Zhida , XU Jiwen , ZHANG Yupei , YANG Ling , QIU Wei

武汉理工大学学报-材料科学版(英文版) doi:10.1007/s11595-015-1288-1

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Effect of Overaging on Solute Distributions and Bake Hardening Phenomenon in Bake Hardening Steels

WANG Hua , SHI Wen , HE Yan-lin , LU Xiao-gang , LI Lin

钢铁研究学报(英文版)

Specimens of two different kinds of bake hardening steels (BH-Mn and BH-P) were prepared and treated with different annealing processes (water quenching and overaging). A novel technique of three dimensional atom probe was used to investigate solute distributions in these steels. The results indicate that C concentration decreases, whereas V increases during overaging in both bake hardening steels. The conclusion that no vanadium carbides precipitate during the overaging is therefore originally obtained by microanalysis in bake hardening steels. Moreover, bake hardening values of all the specimens were tested by tensile experiments with 2% pre-deformation. However, those of overaged specimens were further measured with higher levels of pre-deformation because no bake hardening phenomenon was present at 2% pre-deformation. As the pre-deformation increases from 2% to 6% and 8%, both overaged steels show bake hardening values, and the value data are almost the same.

关键词: ultra-low carbon , bake hardening steel , three dimensional atom probe , solute C , water quenching , overaging , bake hardening phenomenon

Ilmenite Smelted by Oxygen-Enriched Top-Blown Smelting Reduction

LI Hui-bin , WANG Hua , QI Yi-long , HU Jian-hang , LI You-ling

钢铁研究学报(英文版)

Total ilmenite from Yunnan, China, difficult to smelt in blast furnace, was smelted by oxygen-enriched top-blown smelting reduction ironmaking technology. Much more details on smelting were discussed. Specifically, the influence of reduction temperature, slag basicity and molar ratio of carbon to oxygen on the reduction quality level including iron recovery and titanium and sulfur contents in the pig iron produced in the experiment was investigated. Iron recovery rate could reach 95% with titanium content below 005% in pig iron produced, under the conditions of holding time of 30 min at 1823 K, basicity of 11, carbon to oxygen molar ratio of 10 and oxygen-enriched flow rate of 250 L/h. Oxidization potential of top-space of smelting reduction vessel and slag combination could create the driving force to partition phosphorous, titanium and silicon into the slag, which ensured low contents of the impurities involved above and carbon in pig iron. In addition, it avoided the generation of Ti(C,N) that could reduce interfacial tension of slag, which induced the formation of foaming slag seriously. Furthermore, jam of chargings and bubble flooding would be triggered, resulting in deterioration of BF state, increase of iron loss and decline of desulfurization rate.

关键词: smelting reduction , ilmenite , iron recovery , desulfurization

Optimization of Low-Temperature Exhaust Gas Waste Heat Fueled Organic Rankine Cycle

WANG Hui-tao , WANG Hua , ZHANG Zhu-ming

钢铁研究学报(英文版)

Low temperature exhaust gases carrying large amount of waste heat are released by steel-making process and many other industries, Organic Rankine Cycles (ORCs) are proven to be the most promising technology to recover the low-temperature waste heat, thereby to get more financial benefits for these industries. The exergy analysis of ORC units driven by low-temperature exhaust gas waste heat and charged with dry and isentropic fluid was performed, and an intuitive approach with simple impressions was developed to calculate the performances of the ORC unit. Parameter optimization was conducted with turbine inlet temperature simplified as the variable and exergy efficiency or power output as the objective function by means of Penalty Function and Golden Section Searching algorithm based on the formulation of the optimization problem. The power generated by the optimized ORC unit can be nearly as twice as that generated by a non-optimized ORC unit. In addition, cycle parametric analysis was performed to examine the effects of thermodynamic parameters on the cycle performances such as thermal efficiency and exergy efficiency. It is proven that performance of ORC unit is mainly affected by the thermodynamic property of working fluid, the waste heat temperature, the pinch point temperature of the evaporator, the specific heat capacity of the heat carrier and the turbine inlet temperature under a given environment temperature.

关键词: waste heat recovery , organic Rankine cycle , optimization , working fluid , exergy , pinch point