• 한국레이저가공학회지
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• 제10권4호
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• pp.7-12
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• 2007

The aluminized steel sheet exhibits excellent resistance to oxidation and corrosion, and can substitute for stainless steel or heat-resisting steel in some situations. Furthermore it has wide applications, owing to its low cost and excellent performance, in the petrochemical industry, electric power, other energy conversion system, etc. and has attracted the attention of many investigators. Laser welding is a remarkably advantageous method for welding of thin sheets and surface-treated steel sheets since the method requires less heat input, and it is suitable for high-speed welding. In this study, thus, the laser weldability of aluminized steel sheet was investigated. As the result from the study, there is an Al-rich zone in a welded part which has decreased the welding strength due to the intermetallic compounds in the Al-rich zone.

• 대한토목학회논문집
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• 제30권1C호
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• pp.27-35
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• 2010

사질토지반에 진동타입되는 강널말뚝의 거동을 파악하고자 계측기를 부착한 강널말뚝을 각각 1본씩 단독시공 및 연결시공하여 현장시험을 수행하였다. 깊이측정장치를 통해 구한 깊이에 따른 관입속도결과에 따르면 연결부 마찰의 영향이 강널말뚝의 관입속도에 큰 영향을 미친다는 사실을 알 수 있었다. 연결시공시 연결부 마찰은 관입깊이에 대해 불규칙한 양상을 보여주었으며, 그 크기는 19.1kN/m이었다. 진동타입시 강널말뚝은 거의 강체로 거동함이 계측결과를 통해 확인되었다. 단독시공시의 효율계수는 0.42이었으며 연결시공시의 효율계수는 0.71이었다. 계측자료로부터 유도한 하중전이곡선의 양상은 Dierssen이 제안한 그것과 가장 유사하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1575-1578
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• 2005

As GA(Galvannealed sheet steel, GA) has good corrosion resistance, weldability and paintability as well as excellent stamping formability it's demand is rapidly increasing for automotive panel. But the layer of the Galvannealed sheet steel is easy to have a coating layer such as powdering and flaking in the press process because it is composed of Fe-Zn alloy. Therefore, the process condition is properly required to form the surface treated sheet steel. The frictional characteristics with dies are changed according to the annealing temperature, $505^{\circ}C,\;515^{\circ}C\;and\;540^{\circ}C$ during the process. To obtain the frictional characteristics of GA sheet steel in this study, on flat friction test is conducted. The friction coefficient is compared with the variation of pressure and velocity, viscosity of lubricant at the various galvannealed temperatures.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권5호
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• pp.250-257
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• 2006

It is well known that Grain-oriented electrical steel sheets have two dimensional magnetic properties according to the direction of exciting field such as non-linear phase difference between magnetic flux density and magnetic field intensity vectors, different iron loss and permeability even when an alternating magnetic field is applied. The measurement and application of the two dimensional magnetic properties of the Grain-oriented electrical steel sheets, therefore, are very important for the design and precise performance analysis of electric machines made of them. As the direction of exciting field changes, in this paper, the two dimensional magnetic properties of a Grain-oriented electrical steel sheet, i.e., non-linear B-H curves, phase difference between B and H, and iron loss characteristics, are measured using SST(Single Sheet Tester) which has two axes excitation. The measured results are presented in two ways: using $(B,\theta_B)$ method and using hysteresis loops along rolling and transverse directions, respectively.

• 소성∙가공
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• 제22권4호
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• pp.223-228
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• 2013

The friction coefficients of advanced high strength steel sheets were experimentally determined. In the friction test, the pulling and holding forces acting on the sheet for various friction conditions, such as lubricant viscosity, pulling speed, blank holding pressure, sheet surface roughness, and hardness of the sheet were measured and the friction coefficient was calculated based on Coulomb's friction law. While the friction coefficient, generally, decreases as the value of friction factor increases, the factor associated with the sheet surface roughness shows U shape behavior for the friction coefficient. Furthermore, the relationship between friction coefficient and the wear volume, which was computed for the roughness of both sheet surfaces and the friction area, is linearly proportional.

• 한국정밀공학회지
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• 제23권9호
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• pp.149-155
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• 2006

This paper is concerned with the weight reduction of front side member of a vehicle considering the application of high strength steel sheet. The influence of steel sheet grade and thickness on the energy absorption, impact load and deformed shape of front side member is investigated by using reverse engineering and FE-analysis. The reverse engineering is applied to obtain 3D model of front side member from B.I.W for the FE simulation. FE analysis is carried out with commercial crash analysis SW PAM-CRASH. The crashworthiness of front side member is considerably improved with steel sheet strength and thickness increase. From the result of this study the weight reduction in automotive parts for the improvement of the fuel efficiency can be easily achieved with replacing high strength steel without deterioration of crashworthiness.

• 한국생산제조학회지
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• 제23권5호
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• pp.525-531
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• 2014

A cowl cross is a part of the car's instrument panel used to maintain the rigidity of the vehicle body side. The application of laser welding has the benefits of speed and thermal deformation compared to arc welding. An ultra-high strength steel sheet is used to reduce the weight of the vehicle body parts. Generally, formability of such a steel sheet is poor because its elongation is very low. For this reason, a method for cold forming of an ultra-high strength steel sheet is required. This paper describes how to improve the formability and weldability of the ultra-high strength steel sheet. Mechanical tests of this material were also performed to evaluate the welding properties of $CO_2$ (GMAW) and those of laser welding.

• 한국정밀공학회지
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• 제15권7호
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• pp.36-43
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• 1998

Surface roughness of cold rolled steel sheet as well as the coating technique itself is quite important in obtaining high image clarity of electronic products and car outer panels. Especially, surface characteristics of steel sheet have acquired increasing attention from the steel and automotive industries. While the influence of such characteristics on paintability formability and painted surface appearance is important in defining steel surface requirements for automotive industries. Therefore this paper is dedicated primarily to the issue of paint appearance and reviews for improvement of roughness and peak count about the surface of work roll for the actual temper mill. The conclusions were obtained as follows ; 1) Roughness and peak count about the surface of steel sheet is strongly affected by surface condition of work roll. 2) The electro-discharge textured roll has more uniform roughness distribution than shot blasted roll and it's painted appearance of steel sheet has more improvement than that of the shot blasted because it has more harmonic wave roughness, and the higher peak count of surface roughness.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.781-784
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• 2004

Method of Steel plate reinforced by fiber sheet is advantageous in the secure loading facility. For this method are a light weight and a high strength, the thickness of steel can be reduced Effects of composite system are depreciated when the thickness of steel is thin. This is the result of the difference of ductility ratio with steel plate. Steel plate reinforced by fiber sheets confirms the ability of transformation. This is the result of the property of steel materials Steel plate reinforced by fiber sheet didn't display an enough performance when theadhesives are epoxy rosin. This is the result of the slide of the surface of stee1. The adhesive ability is varied by the number and span of anchor bolts. There wasn't happening the separation between steel and epoxy. Thus the method used in combination with anchor and epoxy is best excellent. This is the result of the upward of accumulation effects Shearing force is in proportion to the number of bolts. But the ability of shearing force per one bolt is reducing. Thickness of steel plate reinforced by fiber sheet must be designed so that steel is endure before concrete is wreck.

• Corrosion Science and Technology
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• 제23권3호
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• pp.215-220
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• 2024

Recently, the demand for Zn-Ni electrogalvanized steel sheets for home appliances and automobiles is increasing. Products should have a thick plating (30 to 40 g/m²) on both side with a thin thickness (≤ 0.8 mm) and the highest surface quality. By a high current density operation, current is concentrated in the edge part of the steel sheet, resulting in large surface dent defects due to dendritic plating. This can lead to a low productivity due to low line speed operation. To solve this problem, this study aimed to identify factors influencing dendritic plating. A cylindrical electroplating device was manufactured. Effects of cut edge shape and thickness of steel plate, current density, temperature, flow rate, electrolyte concentration, and pH on dendrite generation of Zn-Ni electroplating were examined. To investigate effect of edge shape of the steel sheet, the steel sheet was manufactured using three processing methods: shearing, polishing after shearing, and laser. Relative effects thickness and cut edge processing methods of the steel plate, current density, temperature, flow rate, electrolyte concentration, and pH of plating solution on dendrite plating were investigated. To prevent dendrite plating, an edge mask was manufactured and its application effect was investigated.