발간논문

Home > KJMM 논문 > 발간논문

Numerical analyses of fluid flow, heat transfer, solidification and inclusion transport in a steel slab caster under the application of static magnetic field were carried out. The effects of magnetic flux density and casting speed on distributions of fluid velocity and inclusion concentration were studied. At low casting speed and high magnetic flux density, the inclusion removal rate is found to be high due to the low inclusion penetration depth. With the increase of inclusion size and the decrease of casting speed, the effect of magnetic field on inclusion removal increases. The position of peak inclusion concentration in the fully solidified slab moves toward the top side of slab with the increase of inclusion diameter. The high magnetic flux density results in a low value of peak inclusion concentration. The inclusions of flotation velocity in the rage of 0.05∼0.36 times the casting speed show the highest peak in inclusion concentration.

keyword : Inclusion removal, Numerical analysis, Magnetic field, Casting speed, Continuous casting, Steel slab

Studies on effects of the initial textures prior to equal channel angular pressing(ECAP) on the texture evolution in the 1050 Al alloy sheets, fabricated by the continuous confined strip shearing (C2S2) process, were conducted. The four different specimens having various initial textures, i.e. the cold rolled, the heat treated, the warm rolled, and the as-cast 1050 Al alloy sheets, were prepared using various thermomechanical processes. Effect of the texture evolution due to ECAP on deep drawbility and planar anisotropy was analyzed in terms of the γ-values and the Δγ-values determined based on the measured pole figures. A feasibility for producing the 1050 Al alloy sheets having high deep drawbility and low planar anisotropy was demonstrated.

keyword : ECAP, Texture, Deep drawbility, Planar anisotropy

Hydrogen is considered to be an ideal energy source in the foreseeable future. The bulk hydrogen is commercially produced by the catalyzed steam reformation of carbonaceous materials. However, CO_2-gas is producted as a by-product which brings about problems of green house. Therefore, it is necessary to develop a new method which is free from the green house effect and good for the fuel cell. Such a hydrogen can be produced from water by using a variety of energy source, such as solar and nuclear energies without detrimental environmental effects, but known, yet, not to be feasible. It is, however, well known that metals or their lower oxides can effectively reduce steam to produce the high quality hydrogen. In this experiment, iron and its oxide pellets were used as reducers to produce hydrogen gas from steam. Reduction was carried out by passing superheated steam through the pellet-bed in a vertical tube furnace at temperatures of 500 to 900℃ and hydrogen gas produced was measured volumetrically. Results show that the effective reduction of steam was obtained at temperature about 800℃ and the reduction reaction follows the linear rate law. It is also worth to note that wustite was the most active reducer among iron and its higher oxides. The yield was found to be about 56 ㏖e% of hydrogen at the consumption rate of water, 10 ㎖ per hour at 900℃. The reduction mechanism was discussed in terms of the cation deficit structure of wustite.

keyword : Hydrogen production, Steam decomposition, Ferrous iron oxide, Steam-iron process