• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.390-398
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• 1999

The thermomechanical control process(in hot rolling strip mill) was employed to produce 2.25Cr-1Mo steel, which is to be construction material for the steam generator for power plant. Although the Conventional processes has been the primary means of producing the 2.25Cr-1Mo steel, an alternative method was used to meet the specification of ASTM heat treatment for A387-22-Classl using autotempering after coiling in hot rolling strip mill. The microstructures, tensile properties at various temperatures, and creep-rupture properties have been investigated to compare the properties with those of materials produced by the conventional process and to certify the application of the thermomechanical control process to an actual process of manufacturing 2.25-Cr-1Mo steel, this in turn, will reduce the cost of the process. About 14 to 34% glanular bainite (remainder proetectoid ferrite) formed in a coil, and this variety of volume fraction stems from the different cooling rates, which varies with position of the coil after coiling. Tensile testing from room temperature to 700$^{\circ}C$ indicated that strength increases with test temperature showing peaks at around 600$^{\circ}C$. Creep-rupture properties have been being investigated at the temperature of 500$^{\circ}C$ with 27.5, 32kg/$\textrm{mm}^2$ loads and have showed no rupture for over 1000 hours.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.115-118
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• 1997

Recently, hot rolling oil lubrication technology is required to face with the new environments such as the rapid introduction of high wear resistent high speed steel roll the development of continuous hot rolling technology. In the hot strip mill, according to rolling and quality required conditions are constrict, Roll material of hot rolling finishing stand is changing Hi-Cr Roll to High Speed Steel [HSS] Roll. The problem of HSS Roll of roll force and strip scale defects are increasing in hot strip mill, So we have tested HSS Roll in hot rolling simulator as rolling condition, rolling speed, draft, hot oil concentration. To reduce roll force and prevent scale defects. We get some merit rolling force, rolling torque, roll wear reduction, roll and strip surface roughness and hot rolling critical oil concentration 0.4%. Finally we are going to investigate the effect of hot rolling oil of on rolling with HSS Roll.

• Corrosion Science and Technology
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• v.10 no.6
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• pp.194-198
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• 2011

This is the first release of an interim report on the development of coating technology of Zn-Mg alloy layers on steel strip by EML-PVD (electromagnetic levitation - physical vapor deposition) process in an air-to-air type continuous PVD pilot plant. It intends to introduce a basic principle of the EML-PVD process together with the high speed PVD pilot plant built in Posco. Due to the agitation effect provided by the high frequency induction coil, simultaneous evaporation of Zn and Mg from a droplet could produce alloy coating layers with Mg content of 6% to 12% depending on the composition of the droplet inside the coil. For its superior corrosion resistance, Zn-Mg alloy coated steel would be a very promising material for automotive, electrical appliances, and construction applications.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.4
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• pp.382-387
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• 2011

In this paper, a LBCC (Latter Bank Cooling Control) for the high strength steel is proposed to obtain the desirable temperature and the property of the material along the longitudinal direction of the steel on the ROT (Run-Out Table) process. A cooling valve is modeled to analyze the response of the ROT banks. The control concept is derived from a field data, a valve model considering the valve response and a TTT (Time-Temperature Transformation) diagram. The proposed control is verified from the simulation results under the various carbon quantities. It is shown through the field test of the hot strip mill that the deviation of the CT (Coiling Temperature) is considerably decreased by the proposed temperature control.

• Journal of the Korean institute of surface engineering
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• v.34 no.2
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• pp.115-124
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• 2001

Gas wiping process of continuously hot-dip galvanized coating on steel strip has noise and coating problems. To improve the qualify of product, characteristics of air flow on the steel surface must be investigated. In this paper, fluid dynamic model of the gas flow is setup and solved numerically using STAR-CD. The effects of edge baffle, distance between steel plane edge and baffle, inlet pressure, and gap between air knife and strip steel surface are investigated, and it is concluded that edge baffle can reduce over-coating and edge built-up.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.80-88
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• 2006

This paper proposes a new steel strip surface inspection system. The system acquires bright and dark field images of defects by using a stroboscopic IR LED illuminator and area camera system and the defect images are preprocessed and segmented in real time for feature extraction. 4113 defect samples of hot rolled steel strip are used to develop KNN (k- Nearest Neighbor) classifier which classifies the defects into 8 different types. The developed KNN classifier demonstrates about 85% classifying performance which is considered very plausible result.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.379-383
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• 2005

This paper proposes a new steel strip surface inspection system. The system acquires bright and dark field images of defects by using a stroboscopic IR LED light and area camera system and the defect images are preprocessed and segmented in real time for feature extraction. 4113 defect samples of cold roll steel strips are used to develop KNN (k-Nearest Neighbor) classifier which classifies the defects into 8 different types. The developed KNN classifier demonstrates about 85% classifying performance which is considered very plausible result.

• Journal of the Korean institute of surface engineering
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• v.32 no.4
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• pp.555-560
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• 1999

Gas wiping of continuously hot-dip galvanized coating on steel strip has generated edge overcoating and noise problems. The overcoating of zinc in the edge zone from edge to 50mm inside of the strip along its width was measured and analyzed. The overcoating is thought to occur due to the reduced impinging pressure of wiping gas onto the strip edges by the boundary effect and it can decrease by 50% or more by applying edge baffles when the baffle-to-strip distance is maintained to 20mm or less. The overcoating was compared with edgedrop of the cold-rolled steel substrate. Edge buildup mostly at the edge area 10 to be 20mm from the edge results in if the edgedrop is not sufficient enough to compensate for the overcoating to be flat on the edgedrop or/and if the overcoating is not small enough to the given edgedrop. Edge baffles can reduce effectively this type of edge buildup.

• Transactions of Materials Processing
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• v.6 no.2
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• pp.118-135
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• 1997

In order to analyze the deformation and residual curvature of steel sheets in the strip processing lines, a program for calculating curvature and work hardening of sheet was developed. Strip deformation caused by repeated bending under tension in the process lines was analyzed on the basis of the incremental-plasticity theory with the mixed hardenting model for the purpose of predicting the strip shape and the yield stress change. The developed calculation program was applied to predict curl and gutter of sheets within a 10% difference. The yield stress increment was also predicted with the similar accuracy. Application of the model to tension legvelling process showed that gutter could be controlled by intermesh and elongation. The yield stress increment in the electro-galvanizing line calculated by the developed program was found to be dependent on the yield strength, the applied tension and the diameter of the smallest roll.

• Journal of the Korean Geosynthetics Society
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• v.8 no.4
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• pp.1-8
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• 2009

In this study, the large-scale pullout tests are conducted to evaluate pullout resistance of steel strip reinforcement with transverse members. The test results clearly showed the passive effect by normal stress. This suggests that both friction resistance and passive resistance by normal stress should be taken into account in the evaluation of pullout resistance for design. Therefore, The evaluation results confirmed that the developed steel strip reinforcement with transverse members depend heavily on passive resistance by normal stress.