• Tribology and Lubricants
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• v.30 no.6
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• pp.330-336
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• 2014

Sintered metallic brake pads and low alloy heat resistance steel disks are applied to mechanical brake systems in high energy moving machines that are associated with recently developed 200km/h trains. This has led to the speed-up of conventional urban rapid transit. In this study, we use a lab-scale dynamometer to investigate the effects of the composition of friction materials on the tribological characteristics of sintered metallic brake pads and low alloy heat resistance steel under dry sliding conditions. We conduct test under a continuous pressure of 5.5 MPa at various speeds. To determine the optimal composition of friction materials for 200 km/h train, we test and the evaluate frictional characteristics such as friction coefficients, friction stability, wear rate, and the temperature of friction material, which depend on the relative composition of the Cu-Sn and Fe components. The results clearly demonstrate that the average friction coefficient is lower for all speed conditions, when a large quantity of iron power is added. The specimen of 25 wt% iron powder that was added decreased the wear of the friction materials and the roughness of the disc surface. However when 35 wt% iron powder was added, the disc roughness and the wear rate of friction materials increased By increasing the amount of iron powder, the surface roughness, and temperature of the friction materials increased, so the average friction coefficients decreased. An oxidation layer of $Fe_2O_3$ was formed on both friction surfaces.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1252-1262
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• 1999

The effect of microstructures on the strength-flangeability of Nb bearing hot-rolled high strength steel was investigated in order to improve the strength-flangeability of conventional TS 580MPa grades HSLA steel for the automotive wheel disc. The low temperature coiling method using 3-step controlled cooling pattern after hot rolling was effective to produce the Nb-bearing high strength steel with the polygonal ferrite and bainite duplex microstructures. It was suggested that the suppressed precipitation of grain boundary cementites and the decreased hardness difference between ferrite matrix and bainite cause the excellent stretch-flangeability of ferrite-bainite duplex microstructure steel. Therefore, the formation and propagation of microcracks were suppressed relative to the conventional HSLA steel with ferrite and pearlite microstructure. In addition, the elongation was improved as compared with that of hot-rolled steel sheets using conventional early cooling pattern because the volume fraction of polygonal ferrite was increased.

• Resources Recycling
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• v.3 no.2
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• pp.9-16
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• 1994

In this study, the grinding and wet cyclone process of the dust for the effective separation of high purity iron powder and iron oxide were investigated. The results obtained in this study can be summarized as follows: 1. By applying the wet cyclone technique for the iron powder(+200 mesh) produced from EC dust of the Kwangyang 2nd steel making factory, the iron powder of high content more than 99.76% of Fe was obtained with 47.66% yield at grinding time of 5 minutes by attritor. 2. The particle size distribution of the iron powder recovered from converter dust is quite simillar with the iron powder of sweden Hoganas Co.(W40.24, W40.29, W40.37, W40.37OX). 3. By using iron powder, copper ions are all adsorbed and removed in any concentration ranges of copper sulfate solution(Cu:100, 200, 300, 600 ppm).

• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.444-449
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• 2016

Industrial by-products generated by integrated iron and steel manufacture cause environmental pollution. The by-products contain not only iron element but also harmful substances. Therefore, in view of to waste recycling and environmental preservation, production of sponge iron using the by-product is considered an effective recycling method. In this study, reduction efficiency of pellets from blast furnace dust was measured. Metallization was found to be increased, as $C/Fe_{total}$ ratio and reaction time were increased. The pellets were formed into a globular shape, and calcined for 60 minutes at $1100^{\circ}C$ in an electric furnace. Phase changes were analyzed using an X-ray diffractometer. Microstructures of the pellets were observed by a scanning electron microscope.

• Analytical Science and Technology
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• v.8 no.1
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• pp.85-90
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• 1995

Corrosion characteristics of 4 kinds of the Fe-Al damping alloys has been studied in the 3.5% NaCl solution and compared with a cold rolled mild steel and pure Ti, No passivation, besides Ti, was observed in the Fe-Al damping alloys and a cold rolled mild steel. Corrosion rate was decreased with lower carbon concentration. In the case of Mn addition for improving damping capacity, corrosion rate was decreased in scrap iron but was not decreased in electrolytic iron. It has been shown that corrosion rate of Fe-Al damping alloys lays between that of the pure Ti and that of a cold rolled mild steel.

• Environmental and Resource Economics Review
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• v.19 no.2
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• pp.341-360
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• 2010

The goal of this study is to forecast the scales of seaborne trade of iron ore and coal. It is assumed that the seaborne trade of iron ore is the function of two independent variables(crude steel production, world GDP) and the seaborne trade of coal is the function of two independent variables(crude steel production, world electricity generation). The result shows that the regressions of two functions are statistically significant respectively. As the results of forecasting, the seaborne trade of iron ore in 2010 may be 892 million tons which is increased 5.1% compare to the level of 2009. Also the seaborne trade of coal in 2010 may be 827 million tons which is increased 6.1% compare to the level of 2009. In terms of the compound annual growth rate, it is forecasted that the iron ore may show 4.7% of increasing rate from 2009 to 2015 and the seaborne trade of coal may be increased 6.1% annually for the same period.

• Resources Recycling
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• v.12 no.5
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• pp.36-41
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• 2003

Although slag has an enough potential as the secondary resources due to its high content of iron, quite a large amount of slags are simply landfilled when market prices of iron and steel are not so beneficial. The purpose of this study is to investigate the basic characteristics regarding the recovery of iron content from slag by magnetic separation method for the enhancement of its recycling rate. Three kinds of slags such as blast furnace slag, water-cooled converter slag, and air-cooled converter slag were tested taking the strength of magnetic field, revolving speed of drum, and feeding rate of slag as the influential factors on the magnetic separation. For blast furnace slag, the recovery of iron was observed to increase as drum speed and feeding rate were lowered. For water-cooled converter slag, iron recovery was raised as feeding rate was increased and drum speed was lowered. Also, finer slag particles were observed to be more favorable for the higher recovery of iron content. Regarding air-cooled converter slags, higher iron recovery was accomplished when both feeding rate and drum speed were increased or decreased. In addition, when the magnetic field strength was increased the iron recovery was raised, however, the iron grade of separated product was observed to diminish because of the co-separation of impurities.

• Corrosion Science and Technology
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• v.17 no.5
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• pp.249-256
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• 2018

Metallic structures in the oil and gas production undergo severe degradation due to sweet and sour corrosion caused by the presence of $CO_2$ and $H_2S$ in the fluid environment. The corrosion behavior of 304 austenitic stainless was investigated in the presence of varying concentrations of $CO_2$ or $H_2S$ and $CO_2+H_2S$ to understand the effect of the parameters either individually or in combination. Potentiodynamic polarization study revealed that a small amount of $CO_2$ aided in the formation of calcareous deposit of protective layer on passive film of 304 steel, while increase in $CO_2$ concentration ruptured the layer resulting in sweet corrosion. The presence of $S^{2-}$ damaged the passive and protective layer of the steel and higher levels increased the degradation rate. Electrochemical impedance studies revealed lower polarization resistance and impedance at higher concentration of $CO_2$ or $H_2S$, supporting the outcomes of polarization study. XRD analysis revealed different types of iron carbides and iron sulphides corresponding to sweet and sour corrosion as the corrosion products, respectively. SEM analysis revealed the presence of uniform, localized and sulphide cracking in sour corrosion and general corrosion with protective carbide layer amid for sweet corrosion.

• Korean Journal of Heritage: History & Science
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• v.46 no.3
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• pp.134-149
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• 2013

The Sudang-ri Site in Geumsan is considered the historic site where Baekje dominated the inland traffic route to Gaya through Geumsan and Jinan in the 5th Century. This study identified the production techniques of iron by conducting an analysis of metallographical microstructure of the artifacts such as an iron sword and an iron sickle that were excavated in Sudang-ri Site, Geumsan, one of the regions ruled by Baekje, and tried to figure out the characteristics and the technical systems of Baekje's ironmaking around the 5th Century by comparing them with other iron artifacts produced around the same time. The analysis showed that various production techniques were applied to the artifacts excavated in Sudang-ri Site, Geumsan. Depending on the production techniques, they can be divided largely into three methods: the simple shape-forging method, the steel manufacture method after forging, and the steel manufacture & heat-treatment method after forging. The iron sickle from the stone chamber tomb No. 1, which was produced only through forging, is mostly composed of soft ferrite at both edges of the blade and at the rear making the use of the weapon impractical. From this fact, it is presumed that they were produced as burial objects or ceremonial accessories for the person buried. The iron axe from the outer stone coffin tomb No. 1 and the iron swords and sickle from the outer stone coffin tomb No. 12, which were produced through the steel manufacture method after forging such as carburizing, did not go through the heat treatment such as quenching, but applied different production processes to each part. Therefore, it is deemed that they were produced as daily tools for cultivation rather than burial objects or ceremonial accessories. The production techniques following the forging process - carburizing and heat treatment - can be found on the iron swords from the outer stone coffin tomb No. 5 and the outer stone coffin tomb No. 12. The sturdy structure of the blade part and the durable structure of the rear processed with heat are deemed to have been produced as weaponry and used by the person buried. Based on the analysis of the iron artifacts excavated from Sudang-ri Site in Geumsan, the characteristics of iron production techniques were investigated by comparing them with the artifacts from Yongwon-ri Site in Cheonan, Bongseon-ri Site in Seocheon, and Bujang-ri Site in Seosan that were made around the same time as the cluster of Baekje tombs examined by the metallographical microstructure analysis of this study. For the iron artifacts analyzed here, the changes in the techniques were investigated using the iron swords common in all of the tombs. In the case of the iron swords, it was identified the heat treatment technique called tempering was applied from the 4th Century.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.48-53
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• 2003

The steel slag, a by-product which is produced on the process of manufacturing steel by refining pig iron is mainly used as road materials after aging it. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the volume expanded. Due to this reason it prevents steel slag from being used as aggregate of concrete. But steel slag used in this study is controled by a air-jet method which rapidly cools substance melted at a high temperature. Rapid cooling prevents from generating of free-CaO in steel slag. In this study, it was investigated that steel slag manufactured by air-jet method affects on concrete in the freezing and thawing. As results of this study, concrete mixed with steel slag was worse in the freezing and thawing than concrete mixed with sand in spite of using air entraining agent. To obtain durability of concrete in the freezing and thawing, it is desirable to mix 50% of steel slag in concrete per unit weight of volume.