• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.74-80
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• 1999

Work roll wear in the cold rolling of mild steel strip is strongly affected by rolling materials, rolling conditions such as roll arrangement in the cold rolling mill and lubrication. The tests were performed to find the effects of roll arrangement n the cold rolling mill on the work roll wear under the same lubricating conditions. The obtained results are as follows:If the distance of cold rolling is about 60km, the surface roughness of its was reduced by half(Ra 0.49${\mu}{\textrm}{m}$) and Pc(peak count) also was decreased to 60 ea/cm.It is easier for CC(Continuous casting) to make a slip on rolling than IC(Ingot casting). It is due to surface mirror in which first residual product appears and iron powder included Al2O3 is sticked. Because bending degree of 4Hi-rolling mill is higher than 6Hi-rolling mill, the first surface mirror was occurred to its center-point which is loaded strongly. 6Hi-rolling mill shape-controlled by intermediate roll doesn't need the initial crown to work roll. Therefore, fatigue and wear would appear a little bit.

• Journal of Korea Foundry Society
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• v.10 no.5
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• pp.435-443
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• 1990

By using the centrifugal atomization, which is one of the rapid solidification processes, Al-5,10wt%Pb alloys which are monotectic alloys were melted at 150K over two liquid phase line in the phase diagram. The melted alloy was poured on the rotating disk, being made into atomized powders, and then the solidified microstructure and morphology of the powder were investigated. This study converted the produced powders into strips by strained powder rolling. According to sintering temperature, the microstructure and hardness were investigated. The solidified structure of the powders were almost cellular dendritic structure. Pb particles ($2.0-3.0{\mu}m$) were fairl distributed in the Al matrix. Powder shapes were irregular. Rolling property and the compacting was good, respectively, because of increasing mechanical interlocking and surface area in the small size powders. With increasing temperature, the boundarys of powders were in porous form due to the diffusion. Pb particles which were surrounding the pores were inverse-segregated at the surface of the powders. With increasing of sintering temperature, the hardness of the powders and the strips decreased. In particular rolling-strip, the hardness abruptly decreased due to the release of work-hardening.

• Journal of the Korean Society of Clothing and Textiles
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• v.10 no.3
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• pp.27-36
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• 1986

The purpose of this study was, to estimate the detergency of commercial detergent and to examine the interrelationship between detergency and detergent characteristics, detergent concentration, fiber characteristics, and Rolling-up phenomenon which is the major removal mechanism of oily soil. A mixture of oleic acid-olive oil was used as oily soil. The detergency was estimated by analysis of oleic acid on cotton ana polyester fabrics before and after washing by means of liquid scintillation counting. The Rolling-up of oily soil from PET film was observed and change of contact angle and removal time were measured. The results were as follows ; 1. In the case of soaps and powder synthetic detergents, the optimum concentrations we-re about $0.2\~0.3\%$. And detergencies of liquid synthetic detergents were considerably low, and the detergency was continually increased up with increasing concentration to $0.5\%$, which seemed to be caused by the lower pH than that of soap and powder synthetic deter-gent solutions. 2. As the effect of external or internal fiber structure; the detergency of cotton was lower than that of polyester. 3. In the observation of Rolling-up, the contact angle increased and the Rolling-up time became shorter with increasing detergent concentrations ($0.05\~0.5\%$). And it was confirmed that detergency was increased with Rolling-up effect. In addition, the study on the actual laundry condition was studied using the questionaire. From the results, about $76\%$ of households used the concentration of detergent roughly or excessively and housewives were highly concerned on the recommended dose, but grade of practice were very low.

• Electrical & Electronic Materials
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• v.9 no.6
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• pp.600-604
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• 1996

High-T$_{c}$, superconducting wire is very important element for the application of electrical power systems. But it is very difficult to develope the long high T, wire with excellent properties. BiSrCaCuO multi-layer tapes are fabricated by a rolling method and pressing method sintered for several step at 840.deg. C. The critical current densities of 637 filament multi-layer tapes sintering 100 hours fabricated by the rolling method and pressing method are 1.3*10$^{4}$ A/cm$^{2}$ and 5.5*10$^{3}$ A/cm$^{2}$. The critical cur-rent densites of multi-layer tapes made by rolling method are found to be better than those fabricated by the powder-in-tube method and pressing process. As result, the rolling method is the best way to fabricated the multi-layer filament.t.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.10b
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• pp.34-35
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• 1998

• Journal of Powder Materials
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• v.14 no.1 s.60
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• pp.13-18
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• 2007

The mother Ni-W (1-5 wt.%) alloy billets for coated conductor substrate were fabricated by powder metallurgy process. The tensile test results for the sintered Ni-W rods showed the increase of mechanical strength and decrease of ductility with increasing W content due to the solid solution hardening. All the fracture surfaces of the tested specimens showed the typical ductile fracture mode of dimple rupture due to the local necking. The Ni-W alloy billets were made into tape by cold rolling. After the appropriate heat treatment for recrystallization, the brass texture formed by the cold rolling was converted to the complete cube texture. The in-plane and out of plane texture of the tapes estimated by x-ray pole figure were smaller than 9 degree and 7 degree, respectively. The effect of the W addition on the texture development seems not to be significant.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.623-629
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• 1995

To investigate the effects of powder shape on U loading density of fuel meat, two kinds of fuel meats were prepared with atomized and comminuted U$_3$Si$_2$ powders by extrusion or rolling process. Extruded fuel meats with atomized spherical U$_3$Si$_2$ powder appeared to have much less porosity than those with comminuted irregular U$_3$Si$_2$ powder at higher U$_3$Si$_2$ fraction- The U$_3$Si$_2$ particles with spherical shape are less fractured in extrusion than in rolling. Most of atomized particles on the whole maintained to have spherical shapes in the extrusion. It has been shown that atomized spherical particles are expected to approach similar upper loading limits comparing with comminuted particles in rolled plates, but exceed comminuted powder loading limits in extruded rods.

• Journal of Powder Materials
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• v.29 no.2
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• pp.123-131
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• 2022

The purpose of this study is to improve the mechanical properties and develop manufacturing technology through self-soluble alloy powder flame spray coating on the surface of a run-out table roller for hot rolling. The roller surface of the run-out table should maintain high hardness at high temperatures and possess high wear, corrosion, and heat resistances. In addition, sufficient bonding strength between the thermal spray coating layer and base material, which would prevent the peel-off of the coating layer, is also an important factor. In this study, the most suitable powder and process for roll manufacturing technology are determined through the initial selection of commercial alloy powder for roll manufacturing, hardness, component analysis, and bond strength analysis of the powder and thermal spray coating layer according to the powder.

• Korean Journal of Materials Research
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• v.28 no.8
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• pp.435-439
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• 2018

MA Al alloys are examined to determine the effects of alloying of Mg and Cu and rolling on tensile deformation behavior at 748 K over a wide strain rate range($10^{-4}-10^3/s$). A powder metallurgy aluminum alloy produced from mechanically alloyed pure Al powder exhibits only a small elongation-to-failure(${\varepsilon}_f$ < ~50%) in high temperature(748 K) tensile deformation at high strain rates(${\acute{\varepsilon}}=1-10^2/s$). ${\varepsilon}_f$ in MA Al-0.5~4.0Mg alloys increases slightly with Mg content(${\varepsilon}_f={\sim}140%$ at 4 mass%). Combined addition of Mg and Cu(MA Al-1.5%Mg-4.0%Cu) is very effective for the occurrence of superplasticity(${\varepsilon}_f$ > 500%). Warm-rolling(at 393-492 K) tends to raise ${\varepsilon}_f$. Lowering the rolling-temperature is effective for increasing the ductility. The effect is rather weak in MA pure Al and MA Al-Mg alloys, but much larger in the MA Al-1.5%Mg-4.0%Cu alloy. Additions of Mg and Cu and warm-rolling of the alloy cause a remarkable reduction in the logarithm of the peak flow stress at low strain rates (${\acute{\varepsilon}}$< ~1/s) and sharpening of microstructure and smoothening of grain boundaries. Additions of Mg and Cu make the strain rate sensitivity(the m value) larger at high strain rates, and the warm-rolling may make the grain boundary sliding easier with less cavitation. Grain boundary facets are observed on the fracture surface when ${\varepsilon}_f$ is large, indicating the operation of grain boundary sliding to a large extent during superplastic deformation.

• Journal of Industrial Technology
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• v.35
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• pp.3-8
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• 2015

A study has been made on defects which are formed in manufacturing processes of engine bearing and also on fatigue crack growth behavior in each step of bearing metal manufacturing. After the first step(sinter brass powder on steel plate ; Series A) many voids are made on brass surface and its size is decreased by the second step(rolling process of sintered plate ; Series B). After the third step(re-sintering step of brass powder and rolling ; Series C) the number of voids is decreased and its type shows line. The time of fatigue crack initiation and the growth rate of fatigue crack are in order of Series A, Series B, Series C. These reasons are that void fosters the crack initiation and growth, and residual stress made by rolling process effects on the crack growth rate in Series B, C. In forming and machining processes by use of final bearing metal, crack was observed at internal corner of flange and peeling off was observed at junction between steel and brass. Owing to the above crack and peeling off, it is considered that there is a possibility of fatigue fracture during the application time.