• Journal of Korean Society of Steel Construction
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• v.28 no.4
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• pp.263-270
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• 2016

Corrosion resistance steel has been widely used for port and offshore structures exposed to harsh coastal and oceanic environments, due to lower corrosion rate. New higher strength corrosion resistance steel tubes named STKM500 in KS D 3300 were recently developed by domestic technology and expected to replace foreign ASTM A690 steel. In this study, tensile test results are included to show higher yield and tensile strength of STKM500. Then, buckling test results obtained from 2m, 6m, and 12m steel tubes are demonstrated, based on which an allowable axial compressive stress curve for STKM500 steel tubes is suggested.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.314-317
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• 2007

Domestic automobile industries have been focusing their effort on development of exhaust manifolds using high temperature stainless steel. Exhaust manifolds fabricated with stainless steels can be categorized into tubular and cast ones. The former is usually manufactured by forming and welding process and the latter by vacuum casting process. In the present study, high temperature mechanical properties of 5 austenitic stainless steels, one was sand cast and the others vacuum cast, were investigated by performing a series of high temperature tensile tests and high temperature low cycle fatigue tests.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.303-306
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• 1999

For the purpose of Military means, explosion proof concrete, which protect the structures from the damage due to the explosion of bomb and maintain its shape, is required to develop. Therefore, in this paper, mechanical and explosionproof properties of concrete are tested under various steel fiber contents and member size. According to the experimental results, compressive, tensile and flexural strength go up with the increase of fiber contents. Energy bearing capacities is higher with the increase of fiber contents. Especially, it is confirmed that slurry infiltrated fiber concrete (SIFCON) gains in high strength and has high energy bearing capacities. SIFCON is expected to apply in the construction of explosion proof structures.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.821-825
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• 2000

Drawing is one of the oldest metal forming operations and has major industrial significance. This process allows excellent surface finishes and closely controlled dimensions to be obtained in long products that have constant cross sections. In drawing of the high carbon steel wire, exit speeds of several hundreds meters per minute are very common. Drawing is usually conducted at room temperature using a number of passes or reductions through consequently located dies. In multi-stage drawing process like this, temperature rise in each pass affects the mechanical properties of final product such as bend, twist and tensile strength. In this paper, therefore, to estimate the wire temperature in multi-stage wire drawing process, wire temperature prediction method was mathematically proposed. Using this method, temperature rise at deformation zone as well as temperature drop between die exit and the next die inlet were calculated.

• Transactions of Materials Processing
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• v.13 no.2
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• pp.160-167
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• 2004

In order to theoretically analyze the creep behavior of high Cr steel at $600^{\circ}C$, a unified elasto-viscoplastic constitutive model based on the consideration of dislocation density is proposed. A combination of a kinetic equation describing the mechanical response of a material at a given microstructure in terms of dislocation glide and evolution equations for internal variables characterizing the microstructure provides the constitutive equations of the model. Microstructural features of the material such as the grain size and spacing between second phase particles are directly implemented in the constitutive equations. The internal variables are associated with the total dislocation density in a simple model. The model has a modular structure and can be adjusted to describe a creep behavior using the material parameters obtained from uniaxial tensile tests.

• Transactions of Materials Processing
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• v.26 no.6
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• pp.372-377
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• 2017

In this paper, an effective design procedure was proposed to design the rib of die structure for auto-body member with ultra-high strength steel (UHSS) having ultimate tensile strength (UTS) of 1.5 GPa. From analysis results of the die structure, structural safety of the die was evaluated with information such as displacement and von-Mises stress. It was concluded that the casting part could be designed in order to reduce tool deformation. A design guideline of the die structure was proposed, especially for the rib structure in the casting part with an optimization scheme and local reinforcement concept. Simulation result following the design guideline fully explained that stability of the tool structure could be obtained simultaneously with weight minimization.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.3
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• pp.129-136
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• 2000

In the side of military purpose, the explosion proof concrete, which contributes to protect the military facilities from damages due to the explosion of bomb and to maintain their shapes, is required to develop, Therefore. in this paper, mechanical and explosion-proof properties of concrete are tested under various steel fiber contents and member size. According to the experimental results, compressive, tensile and flexural strength gain higher levels with an increase in fiber contents. It shows that energy bearing capacities are higher with an increase in fiber contents. Especially. it is confirmed that slurry infiltrated fiber concrete(SIFCON) gains high strength and has high energy bearing capacities. SIFCON is expected to be applied in the construction of explosion proof structures.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.281-285
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• 2008

Ferritic stainless steel is used for parts of exhaust system of commercial vehicle, because it has such advantages as low price and high corrosion resistant compared with austenite stainless steel. Even though ferritic stainless steel has these merits, to manufacture multi-layer bellows with complex geometry, austenite stainless steel is being used in the industry, because of it's high ductility. However, recently, the mechanical property of the ferritic stainless is getting improved and alternating austenitic stainless steel. In this paper, the possibility of mass production of bellows made of ferritic stainless steel like MH1 and 443CT is studied. Tensile test and ridging test are carried out to observe mechanical properties of STS304, MH1 and 443CT. Forming analysis using FEM is performed to investigate plastic strain during forming process. Prototype bellows has been made using STS304, MH1 and 443CT, respectively, and fatigue tests are carried out to evaluate fatigue life of bellows.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.356-365
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• 1999

The present study is aimed at developing the TRIP(transformation induced plasticity) aided high strength low carbon steel using reversion process. An excellent combination of elongation over 40% and tensile strength abut 100kgf/$\textrm{mm}^2$ achieved in processing of 0.15C-0.5 Si-6Mn steel by slow heating to intercritial temperature region and accelerated cooling into room temperature. This good combination is caused by TRIP phenomena of retained austenite in steels during deformation. The stability of retained austenite is very important for the good ductility and it depends on the diffusion of carbon and manganeses during heat treatment. The accelerated cooling after holding at annealing temperature retards the formation of pearlite and provides the carbon enrichment in retained austenite in steel, resulting in the increase in elongation of the cold-rolled TRIP steel. On the other hand, heat treating the steel at 600$^{\circ}C$ for 5 hour before cold rolling increases elongation but reduces the amount of retained austenite after reversion processing. It is accounted that the heat treating is effective for the increase in the stability of retained austenite.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.135-143
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• 2002

This study is to investigate its use by applying stainless steel wire mash reinforcement method of construction, which is newly developed, on the high strength concrete beam mixed with polymer-steel fiber. In this test, it is investigated and observed such as follows: the ultimate load, the initial flexure crack load, the initial diagonal tension crack load, the relation between load and deflection, load-strain relation, and also crack growth and fracture aspect by increasing load. The results of this test are; first, the stainless steel wire showed some useful reinforcement effects in multiplying the steel's resisting force of moment to the tensile force of beam or slab: second, the promoting strength and internal force was made in the process of the integration at the same reaction by using the penetrating polymer-mortar with an excellent durability and physical property. On the basis of this results, because such instances in applying stainless steel wire Mash reinforcement method of construction have been few so far, through the experimental investigation such as this test over and over again, the efficient and useful method must be developed for the practice.