발간논문

Home > KJMM 논문 > 발간논문

Improvement of characteristics of pseudo particle formation is affected by surface area of nucleus particle, contact angle (r·cosθ) of adherent particle and size distribution of raw sinter mix. Therefore, production rate of iron ore sinter is increased by improvement of permeability on sinter bed through improvement of pseudo-particle formation. This fact was defined by following results; 1. Critical Water content of pseudo-particle formation is changed by surface area of nucleus particles of iron ore brand. Increase of granular index of pseudo-particle formation is dependent upon surface areas of nucleus particles. 2. Decreased r·cosθ of adherent particles, in which increase of the Al₂O₃content is found on the contrary, improved granular index of pseudo particle. Therefore, Al₂O₃/SiO₂as well as reduction degradation index is increased.

keyword :

The precipitation process in 17-4 PH stainless steel was investigated by measuring the changes in electrical resistivity at the liquid nitrogen temperature. From the results of derivatves of resistivity changes obtained by isochronal aging, three kinds of precipitation reactions P1, P2 and P3, tentatively named, were detected at about 410℃, 450℃ and 650℃ respectively. The activation energy for P1 precipitation reaction determined from resistivity measurement was about 49㎉/㏖ and this P1 precipitation was interpreted as the formation of Ni-rich zone. P1 was detected more evidently during re-aging at low temperature after high temperature aging at 560℃. The activation energy for P2 reaction was about 53㎉/㏖ and P2 was interpreted as the formation of Cu-rich phase.

keyword :

The effects of substituting W for Mo on Mechanical Properties in a quenched and tempered martensitic AISI 4340 steel were investigated. The alloys containing 0.3-0.6 w/o W exhibited 35-75% increase at room temperature in impact toughness over the alloy containing 0.25% Mo after tempered at 600℃. However, the yield strength and the ultimate tensile strength were not increased significantly by substituting W for Mo. The mechanical properties were not improved greatly the W content exceeded about 0.4 w/o. Therefore it is recommended that 0.3-0.4 w/o W is suitable for optimizing the strength and the toughness when substituting W for Mo in AISI 4340 steel.

keyword :

Gas flow is affected by physical properties of burden in packed bed of iron blast furnace. The gas permeability with the different size of ore in a packed bed is studied to show the following results. 1. Apparent and bulk density of the sinter in 4DL in POSCO are decreased with the ore size. 2. Pressure drop equation of packed bed is satisfied with Ergun equation. 3. Pressure drop is increased with the addition of -5㎜ sinter ore.

keyword :

keyword :

keyword :

keyword :