• Journal of Ocean Engineering and Technology
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• v.18 no.2
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• pp.70-76
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• 2004

In the steel marking industry, most companies have adapted the continuous casting process, due to its economical benefit. Casting rolls are utilized for frictional drive and the transport of solidifying slap. Dimensional tolerances, mechanical stability, and surface condition of the casting rolls can affect both the surface and the internal quality of the product being cast. To overcome these problems, the industry now is focused on accelerating the rate of technological improvements. This study has been undertaken for the development of casting rolls overlaid materials (SAW FCW wire), with the addition of Vanadium and Molybdenum to the martensitic stainless steel, in order to increase tensile strength and hardness at elevated temperatures.

• Journal of Power System Engineering
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• v.8 no.3
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• pp.30-35
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• 2004

In the steel making industries, the continuous casting process has been applied to the number of company because of its economical benefit. Casting rolls are utilized for frictional drive and transport of solidifying slap. Dimensional tolerances, mechanical stability and surface condition of the cast roll can affect both the surface and internal quality of the product being cast. To overcome these problems, the industry is accelerating on the rate of technology improvements. Samples were overlaid on the S45C steel by submerged arc welding process. And the hardness, wear, electrochemical corrosion and oxidation tests were carried out. Test results were that all these materials were satisfying basic requirements of caster rolls. By these results, the addition of 0.1%Nb and 0.15%V increase mechanical properties and tempering resistance by its superior carbide forming characteristics in low carbon $12{\sim}13%Cr$ martensitic stainless steels.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.189-205
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• 1996

The twin-roll type strip continuous casting process(or direct rolling process) of steel materials is characterized by two rotating water cooled rolls receiving a steady supply of molten metal which solidifies onto the rolls. A solidification analysis of molten metal considering phase transformation and thermofluid is performed using finite diffefence method with curvilinear coordinate to reduce computing time and molten region analysis with arbitrary shape. An enthalpy-specific heat method is used to determine the temperatures inthe roll and the steel. The temperature distribution of cooling roll is calculated using two dimensional finite element method, because of complex roll shape due to cooling hole in rolls and improvemnt accuracy of calculation result. The energy equaiton of cooling roll is solved simultanuously with the conservation equaiton of molten metal in order to consider heat transfer through the cooling roll. The calculated roll temperature is compared to experimental results and the heat transfer coefficient between cooling roll surface and rolling material(steel) is also determined from comparison of measured roll temperature and calculated temperature.

• Journal of Korea Foundry Society
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• v.43 no.2
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• pp.55-63
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• 2023

Due to the importance of the surface on the final slab quality, it is essential to maintain a smooth segment roll surface that is in touch with the thin solid shell during solidification. In this paper, the surface of the used continuous casting guide roll was analyzed to realize the mechanism of its surface deterioration. Surface analysis has revealed severe corrosion at two distinct areas leading to deep roughness occurring on the guide roll. Firstly, the severe corrosion follows prior austenite grain boundary due to exposure with acidic environment. Also, in heat affected zone (HAZ) where two cladding beads overlap, more severe corrosion takes place. The overheat input results in local ferritization without full melting which increases retained δ-ferrite content almost 10 times higher than surrounding area. Corrosion was observed to happen at the δ-γ interface where Cr depletion takes place.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.913-922
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• 1987

In this paper the solidification phenomena at the molten pool has been modeled and simulated in terms with the one dimensional unsteady-state heat transfer of the solid and molten phase and the pressure distribution in the solid phase for the twin-roller continuous casting of Sn-15% Pb. The further purpose of this study was to effectively analyze the thermal and mechanical deformation of roll applying the results of the heat transfer and the pressure distribution to the boundary conditions. The strip thickness of rapidly solidified metallic strip decreases with increasing angular velocity of the roller and with increasing initial roll gap. For this reason the roll spacing and angular velocity of the rolls are considered to be main variables. The recommended optimal casting regimes for continuous strip dimensions is near 0.8mm-1.0mm in thickness at the given angular velocity .omega.=2.0 rad/sec. Results of the experiment using Sn-15% Pb are compared with model predictions. The calculated roll deformation has been in good agreement with the observed value of roll deformatiion. All the deformation. All the deformation of the roller is within the elastic range, the plastic yielding are not occured. However, these elastic stresses are sufficient to take place of the shortened roller life by the thermal fatigue and a notch fatigue. The higher cooling rates were obtained by a twin-roller quenching technique. Also the quenched microstructure of the rapidly solidified shell was verified.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.109-113
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• 2002

Steel industry is the most capital intensive and the largest energy consuming industry, which operate huge and complex facilities to supply various steel products as the primary materials to almost every manufacturing industry Major steel products are hot-rolled and cold-rolled coils, plates, and wires that are produced through molten iron making, molten steel making, casting, and rolling. Each process runs in batch between setups and the specifications or bach are different with each other High energy consuming and heavy material handling require careful synchronization or processes, as well. Considering the synchronization or processes, the lot planning and scheduling problem in the integrated steelmaking process rovers the roll grouping with given casts. the sequencing or rolls over time, and the machine assignment and time scheduling or charges and casts. The problem is investigated by dividing it into two cases whether single or parallel machines at the molten steel making and the continuous casting processes. Problem descriptions and solution approaches or each instance are introduced. To test their performance and conformity, implementation or the algorithms and numerical experiments are carried out with real world and constructed data sets.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.3-9
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• 1999

The recent technical trend in hot rolling of steel can be described as process and product technologies which have been progressed with modern mill equipment and computers. Precise gauge and width control can be achieved by up-to-date control methods such as AGC and AWC systems. Roll benders and various shape control systems enabled high quality flatness and crown control. Mills can produce higher tensile materials by new process based on process metallurgy. The use of high speed steel rolls and on line roll grinders make the schedule free rolling easier which results in cost saving. Process itself goes toward continuous and simple flow type which has lower operation. Endless rolling and strip casting are examples of the trend. Materials with higher tensile strength and various functions have been developed in last years to meet the customer's needs and this trend will continue.