• Journal of Korea Foundry Society
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• v.41 no.6
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• pp.543-549
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• 2021

Aluminum cast iron has excellent oxidation resistance and good resistance to sulfide and corrosion. Compared to Ti and Ni alloys, it is expected to be a substitute material for structural materials and stainless steels because it is relatively inexpensive to use Fe, which is a non-strategic element. This results in a weight reduction effect of about 30% as compared to the use of stainless steel. With regard to aluminum as an alloying material, it is an element that has been widely used for the alloying of cast iron in recent years. Practical use has been delayed owing to the resulting lack of ductility at room temperature and the sharp decrease in the strength above 600℃ of this alloy, however. The cause of the weak room temperature ductility is known to be environmental embrittlement by hydrogen, and the addition of various alloying elements has been attempted in order to mitigate these shortcomings. Although alloying elements such as vanadium, chromium, and manganese are mainly used to increase the hardness and wear resistance of gray cast iron, the price of finished products containing these elements and the problems associated with alloys with this material impose many limitations.

• Journal of Powder Materials
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• v.14 no.6
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• pp.367-371
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• 2007

P/M high speed steel (1.26% C, 4.42% Cr, 6.54% W, 4.92% Mo, 3.21 % V, 8.77% Co, bal. Fe) was applied to hot former die. It showed that the die life became 2.7 times higher than that of cast/wrought SKH 55 tool steel which is commercially used. The increase of die life was corresponding to the improved hardness and transverse rupture strength of PM high speed steel due to the finer grain and carbide as well as the uniform carbide distribution. The P/M high speed steel with the promoted die life could be an alternative to the conventional SKH55.

• Journal of the Korea Concrete Institute
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• v.21 no.6
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• pp.737-744
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• 2009

In this study, the flexural behavior of steel fiber reinforced ultra high performance concrete (UHPC) was investigated. It presents experimental results of steel fiber reinforced UHPC with steel fiber content of 2% by volume and steel reinforcement ratio of less than 0.02. This study aims at providing more information about UHPC beams in bending in order to establish a reasonable prediction model for flexural resistance and deflection in structural code in the future. The experimental results show that UHPC is in favor of cracking behavior and ductility of beams, and that the ductility indices range from 6.29 to 10.44, which means high ductility of UHPC. Also, the flexural rigidity of beam whose cast is begun from end of beam is larger than that of beam whose cast is begun from midspan of beam. This result represents that the flexural rigidity is affected by the placing method of UHPC.

• Transactions of Materials Processing
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• v.19 no.6
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• pp.378-386
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• 2010

Nowadays there has been great interest in using heat treated cast material for press dies due to several advantages like reduction in die production costs. However, in hot press forming processes H13 forged tool steel is mostly used. Cooling performance of dies in hot press forming processes is considered as an important factor of study and also the IHTC parameter between cast material die and sheet metal should be considered as an essential. In the present study, the IHTC was calculated for the sheet metal in the hot press forming process with cast and forged material dies. The temperature measurements were performed for the sheet metal, casting and forged material dies by applying various contact pressure in hot press forming. IHTC was calculated and studied by adopting the inverse heat convection method in DEFORM-2D. Each IHTC was considered as a function of contact time and contact pressure. The experimental data were compared with calculated data obtained from the proposed equation and references.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.2 no.2
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• pp.146-152
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• 2002

Mold level control has been a major control task for continuous casting plants. The system involves nonlinearities such as stick-slip friction in the sliding gate, time-delay, friction force variations between molten steel and the inner wall of mold, and nozzle logging/unclogging. These complex problems should be solved to control mold level for steel cast. In this paper, we propose a neural fuzzy mold level control technique for solving these complex problems and give experiment studies to show the mold level control in continuous casting process.

• Steel and Composite Structures
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• v.6 no.2
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• pp.123-138
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• 2006

This paper proposes a model for the analysis of the construction sequences of steel-concrete composite decks in which the slab is cast-in-situ for segments. The model accounts for early age shrinkage, such as thermal and endogenous shrinkage, drying shrinkage, tensile creep effects and the complex sequences of loading due to pouring of the different slab segments. The evolution of the structure is caught by suitably defining the constitutive relationships of the concrete and the steel reinforcements. The numerical solution is obtained by means of a step-by-step procedure and the finite element method. The proposed model is then applied to a composite deck in order to show its potential.

• International Journal of High-Rise Buildings
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• v.5 no.4
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• pp.293-304
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• 2016

The diagrid structural system for constructing tall buildings is a recent invention. Debuting in 2004 with the construction of the Swiss Re Tower in London, this aesthetically driven structural system has centered the perfecting of its technology on the development of the nodes that form its innovative deviation from standard steel tall framing methods. The paper examines variations in node design, understanding the linked dependence the modularity and the choice to expose the steel in the building, as well as on advances in digital modelling that allow an increasingly seamless line of communication from the engineering design through to the actual fabrication of the nodes. This advanced design and fabrication technology will be seen to have resulted in the expanded use of the technical term "node" to inform the design and construction of a range of other applications in the structuring of tall buildings, including the use of steel castings.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.1
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• pp.39-44
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• 2015

The fracture toughness of 2.25Cr-1Mo cast steel (SA217-WC9) samples which were taken from the check valves of feed water piping of Korean Standard Nuclear Power Plant(KSNPP) was measured by Master Curve method. The measured $T_0$ reference temperature of SA217-WC9 steel was $-30^{\circ}C$. The obtained $T_0$ was compared to the derived value from Charpy impact test data following to SINTEP procedure. The heat-to-heat variation in fracture toughness of SA217-WC9 steel was observed. It was found that the low toughness of a heat of SA217-WC9 steel was attributed to the coarse MnS inclusion originated by high sulfur content as the results of microanalyses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.94-102
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• 2020

Precast concrete segment arch system has an economic and construct ability that combined with advantage of precast concrete and arch behavior. A precast concrete segment arch system with outrigger is consisted of segmented precast panels, a steel outrigger rib, and V-strip to connect precast panels with a steel outrigger rib and cast-in-place anchors in precast panels to connect V-strip should have sufficient pull-out capacity to form its arch shape by site lifting for assembled precast panels and outriggers. However, it is difficult to secure its embedment depth due to the relatively shallow thickness of precast panel. It can be also occurred that flexure deformation of precast panels caused by its pull-out behaviors. In this study, pull-out capacity of cast-in-place anchor was examined for construction of precast concrete segment arch system with outriggers. Therefore, a total of 24 precast panel specimens were fabricated to examine pull-out capacities of cast-in-place anchor in precast panels, and installation depth of anchors, diameter of anchors and wire mesh effects for the precast panel were examined. From this pull-out tests, its pull-out capacities and failure modes were evaluated and the type of the cast-in-place anchor applicable to the precast concrete segment panel arch system with outriggers was determined from comparison of the design specification values.

• Journal of Korea Foundry Society
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• v.25 no.1
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• pp.23-29
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• 2005

Mechanical characteristics of Hi-Cr cast irons containing 16.8%Cr and 3.0%C were studied with various heat treatments. After as-cast Y-block ingots were annealed fully, the ingots were machined into cylinderical specimens with the size of 9mm in diameter and 20mm in length in order to investigate the effect of heat-treatments on mechanical characteristics of high Cr cast irons. All specimens were heat-treated by quenching- tempering, austempering and cyclic heat at the various temperatures(950, 1000, 1050 and $1100^{\circ}C$) respectively. The wear amount was measured for each heat-treated specimens against the counterpart of a hardened SKD11 steel at the following conditions; wearing velocity: 0.7 m/s, load: 100N and sliding distance: 70 km. After as-cast specimens were annealed, fine $M_{3}C$ carbides were formed, which affected the hardness and the wear resistance of Hi-Cr specimens. High hardness and good wear resistance were appeared on the specimens treated at 950 and $1000^{\circ}C$ and the austempered specimens show excellent wear resistance as well as high hardness.