• Journal of Welding and Joining
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• 제18권6호
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• pp.62-67
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• 2000

Metallurgical characteristics of bonded region and high temperature mechanical properties of heat resistant alloy, Fe-35Ni-26Cr during liquid phase diffusion bonding were investigated employing AM17 insert metal. The insert metal for bonding, AM17 was newly developed Ni-base metal using interpolation method. Bonding of specimens were carried out at 1,403~1,463K for 600s in vacuum. The microconstituents in the bonded interlayer disappeared in the bonding temperature over 1,423K. The microstructures, alloying elements and hardness distribution in the base metal. The tensile strength and elongation of the joints at elevated temperatures were the same level as one of the base metal in the bonding temperature over 1,423K. The creep rupture strength and rupture lives of joints were almost identical to those of base metal.

• Steel and Composite Structures
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• 제8권3호
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• pp.179-200
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• 2008

This paper reports the results of a recent experimental study into the behavior of welded fin-plate connections to both hollow and concrete filled tubular (CFT) columns under shear. Experiments have been performed at both ambient and elevated temperatures with the aid of an electric kiln. The observed failure modes include fracture of the fin plate and tearing out of the tube around the welds. By considering the results of previously published research, the current design method for similar connections under purely tensile load, in CIDECT Guide 9, based on a deformation limit of 3% of the tube width is shown to be inadequate when evaluating the ultimate strength of such connections. By comparing the results from the current test program which failed in the fin-plate with Eurocode guidance for failure of a fin-plate alone under shear and bending load it is shown that the column face influences the overall connection strength regardless of failure mode. Concrete in-fill is observed to significantly increase the strength of connections over empty specimens, and circular column specimens were observed to exhibit greater strength than similarly proportioned square columns. A finite element (F.E.) model, developed using ABAQUS, is presented and validated against the experimental results in order that extensive parametric tests may be subsequently performed. When validating the model against elevated temperature tests it was found that using reduction factors suggested in published research for the specific steel grades improved results over applying the generic Eurocode elevated temperature steel strength reduction factors.

• 한국생산제조학회지
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• 제20권6호
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• pp.785-792
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• 2011

Equal channel angular(ECA) pressing is the established processing technique in which a polycrystalline metal is pressed through the die to achieve a very high plastic strain. Therefore, the capability to produce an ultra-fine grain size in the materials is provided. To investigate that mechanical properties at elevated temperature have the ultrafine grain ECA pressing, experiments were conducted on an Al-4.8% Mg-0.07% Mn-O.06% Si alloy. After having been solution treated at 773K for 2hrs, the billet for ECA pressing was inserted into the die. And it was pressed through two channel of equal to cross section intersecting at a 90 degree angle. The billet can be extrude repeatedly because of 1:1 extrusion ratio. Since the billet is passed through the cannel for 2 times, a large strain is accumulated in the alloy. The tensile tests on elevated temperature were carried out with initial strain rate of $10^{-3}s^{-1}$ at eight temperature distributed from 293K to 673K.

• Journal of Welding and Joining
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• 제18권3호
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• pp.106-113
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• 2000

Single crystallization behavior ad high temperature tensile properties of TLP bonded joints of Ni-base single crystal superalloy, CMSX-2 were investigated using MBF-80 and F-24 insert metals. CMSX-2 was bonded at 1523~1548K for 1.5~1.8ks in vacuum. The (100) orientation of bonded specimen was aligned perpendicular to the joint interface. Crystallographic orientation analyzed points over the bonded region possessed the almost same orientation across the joint interface and misorientation $\Delta^{\theta}$ was negligibly small in as-bonded and post-bond heat-treated situations. It was confirmed that single crystallization could be readily achieved during TLP bonding. The tensile strengths of all joints at elevated temperatures were equal to or greater than those of base metal the range of testing temperature between 923K and 1173K. The elongation and reduction of area in values were almost the same as those of base metal. SEM observation of the fracture surfaces of joints after tensile test revealed that the fracture surface indicated the similar morphologies each other, and that the fracture of joints occurred in the base metal in any cases.

• 한국생산제조학회지
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• 제23권5호
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• pp.519-524
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• 2014

The use of light weight magnesium alloy offers significant potential towards improvement of the automotive fuel efficiency. However, the application of formed magnesium alloy components in auto-body structures is restricted due to the low formability at room temperature and lack of knowledge for processing magnesium alloys at elevated temperatures. In this study, a warm tensile test of magnesium alloys was performed to measure tensile strength and elongation. An improvement in formability was confirmed at increased temperatures above about $250^{\circ}C$. Car body warm forming technology was conducted for forming forming reinforced dash components of the magnesium alloy AZ31B sheet at elevated temperatures.

• Elastomers and Composites
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• 제1권1호
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• pp.56-62
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• 1966

The aging characteristics of vulcanized rubber products manufactured in Korean industries have been studied, especially in terms of relationship between aging temperature and time, and also the comparison of results between Geer's oven testing and tube testing was made. It was assessed from changes in tensile properties resulting from conditioning at elevated temperatures for specified period of time. Even though the recipe of each sample is different, the results, as would be expected, has shown that at lower aging temperature the change of tensile strength indicate moderately and at the elovated severely as shown in Figure 9. Consequently, in spite of that the results from conditioning at various temperatures for certain specified period of time must be equivalent to each other, it shows inignorable tolerance. The results of Geer's oven test and tube test have shown slightly different value. It seemed to be caused by the result of migration phenomena on aging in Geer's oven.

• 대한기계학회논문집
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• 제6권2호
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• pp.101-106
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• 1982

This study was undertaken to determine tensile properties and low-cycle fatigue behavior of 0.6%C high carbon steel used of structural purposes at temperatures up to 500.deg.C. In the low-cycle fatigue test the upper limit was decided by elongation(i.e. the total strain range), while the lower limit was defined by the load (i.e. zero load). The following results were obtained. Both, the ultimate tensile strength and low-cycle fatigue resistance attain the maximum values near 250.deg.C. Above this temperature the values decrease rapidly as the temperature increases. The low-cycle fatigue resistance decreases whenever there is an increase of the total strain range. Because the hardness of cycle fatigued specimen correlates cyclic hardening and cyclic softening, therefore the hardness of cycle fatigued specimen is smaller than that of the nonfatigued specimen at room temperature and 500.deg.C but much larger than the hardness of the nonfatigued specimen near 250.deg.C.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.110-116
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• 2002

At elevated temperature, very complex precipitations occur in STS316. To investigate the effect of the precipitation on mechanical properties in SIS316, tensile tests and fatigue crack growth tests were carried out at $650^{\circ}C$ using artificially degraded materials. The material degradation was simulated by aging for up to 20000 hrs. at $750^{\circ}C$, which is equal to 179000hrs (about 20yrs) of service life at $650^{\circ}C$, after conducting solution treatment for 20 min. at $11300^{\circ}C$. The result of the hardness test and the tensile test showed that both properties are closely related to the mean free distance of carbides. Also, from the results of fracture tests at $650^{\circ}C$, ${\triangle}K_{th}$, after values were found to decrease as aging time and microstructure, as the volume fraction of $\sigma$ phase increased.

• Steel and Composite Structures
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• 제51권3호
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• pp.271-288
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• 2024

The primary objective of this study is to investigate the production and performance characteristics of structural concrete incorporating varying proportions (0%, 25%, and 50% by volume) of pumice stone, as well as aluminum lathe as an additive at 0%, 1%, 2%, and 3%, under fire conditions. The experiment will be conducted over a period of up to 1 hour, at temperatures ranging from 24℃, 200℃, 400℃ and 600℃. For the purpose of this, a total of twelve test samples were manufactured, and then tests of compressive strength (CS), splitting tensile strength (STS), and flexural strength (FS) were performed on these samples.Next, a comparison was made between the obtained values and the influence of temperature. To achieve this objective, the manufactured samples were placed at temperatures of 200℃, 400℃, and 600℃ for a duration of 1 hour, and were subjected to the influence of temperature.These values at 24 ℃ were then contrasted with the CS results obtained from test samples that were subjected to the temperature effect for an hour at 200 ℃, 400 ℃, and 600 ℃. A comprehensive analysis of the test outcomes reveals that the incorporation of aluminum lathe wastes into a mixture results in a significant reduction in the compressive strength of the concrete. As a result of this adjustment, the CS values dropped by 32.93%, 45.70%, and 52.07%, respectively. Furthermore, It was shown that testing the ratios of pumice stone alone resulted in a decrease in CS outcomes. Additionally, it was found that the presence of higher temperatures is clearly the primary factor contributing to the decrease in the strength of concrete. Due to elevated temperatures, the CS values decreased by 19.88%, 28.27%, and 38.61% respectively.After this investigation, an equation that explains the connection between CS and STS was provided through the utilization of the data of the experiments that were carried out.

• 한국재료학회지
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• 제15권1호
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• pp.25-30
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• 2005

The microstructural changes by hot extrusion of AZ31B magnesium alloy were observed, and the relation to the tensile property was examined. The tensile properties as oriented longitudinal(L), half transverse(HT) and long transverse(LT) to the extrusion direction were investigated at $20^{\circ}C,\;100^{\circ}C,\;200^{\circ}C,\;300^{\circ}C\;and\;400^{\circ}C$, respectively. As the results, many recrystallized small grains distributed uniformly in large banded microstructures formed along the extrusion direction. The grain size of as-extruded specimen was around $30\~150\;{\mu}m$. As increasing the test temperature the tensile and yield strength with respect to the angle between the axis of the tensile and the longitudinal direction in extrusion was decreased, but their elongation were increased and their deviation between L and LT specimens have disappeared from $300^{\circ}C$. This mechanical anisotropy was reduced at elevated temperatures and almost disappeared at $400^{\circ}C$. It was considered that the homogenization was occured by the recrystallization and the change of slip system was occurred during tensile test process in elevated temperatures.