• Journal of Korean Society of Steel Construction
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• v.27 no.4
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• pp.377-386
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• 2015

In this study, inelastic buckling strength of HSA800 steel columns were tested to investigate the applicability of current column curve (KBC2009, 2010 AISC-LRFD) to HSA800 steel. Key test variables included width-thickness ratio, plate-edge restraints, and column slenderness ratio. Specimens made of ordinary steel (SM490) were also tested for comparison purposes. All the concentrically loaded HSA800 specimens exhibited sufficient buckling strength compared to the current column curve, but some of SM490 specimens showed understrength. This difference can be explained by the lower residual stress present in HSA800 specimens.

• Journal of Welding and Joining
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• v.16 no.5
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• pp.134-141
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• 1998

In this study, a fillet size for bending fatigue strength of one side fillet welded T-joint, used in box type girder and other welding structure, was investigated by bending fatigue test with or without edge preparation and burn through, with variation of joint shape. As a result, the following conclusions were obtained. (1) In one side fillet welded T-joint, the larger the leg length, the greater the bending fatigue strength. The increase in bending fatigue strength. (2) One side filet welded T-joint with edge preparation showed higher bending fatigue strength than that with twofold-large leg length and without edge preparation. (3) In one side fillet welded T-joint without edge preparation, both manual welding and automatic welding were carried out with same condition. In this case, automatic welding shoed deeper penetration and more increased horizontal leg length than manual welding, so that automatic welding offers grater bending fatigue strength. (4) For one side fillet welded T-joint without edge preparation, the ratio(h/t) of the leg length (h) and the main plate thickness (t) in which toe crack can occur was 1.2 over. (5) In one side fillet welded T-joint with edge preparation, the burn through led to reduced bending fatigue strength. However, this bending fatigue strength was higher than that of one side fillet welded T-joint without edge preparation and with a larger leg length.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.463-471
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• 2014

As building height and span is getting taller and longer, the researches to increase material's strength and serviceability are continuously performed. This study evaluated mechanical and chemical properties of newly developed high-strength steel (HSS) for building structures, namely HSA800 and verified cost-effectiveness and applicability of HSS for a tall building by comparing the analysis results of normal strength steel (SM490) model. HSA800 was manufactured by TMCP to have a good weldability in spite of HSS and satisfied Korean Industrial Standards (KS). The analysis results for evaluating cost-effectiveness show that total steel quantity could be saved approximately 30% when using HSS compared to SM490. It is expected that HSA800 will contribute to enhance constructability of building.

• Journal of the Korean Society of Safety
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• v.34 no.6
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• pp.7-12
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• 2019

Flux Cored Arc Welding (FCAW), which has been widely used in many industries, was developed in the 1950s to supplement shortcomings of the Shielded Metal Arc Welding (SMAW). FCAW has an advantage in that it can weld regardless of postures and give good quality results in the filed with many different working conditions. In this study, SM490A (rolled steel for welding structural purpose) with different thicknesses (L:25T+R:30T) were welded using FCAW. Then the mechanical properties (tension test, bending test, hardness test, impact test and macro test) were analyzed and the following conclusions were drawn. In the tensile test, it exceeds the KS standard tensile strength range (400~510) in all welding positions, which means there is a problem in the tensile force transmission performance. In the bending test, it was found that most of the specimens did not exhibit surface rupture or other defects during bending test and they exhibit sufficient toughness even after plastic deformation. In the hardness test, all the results were lower than the standard value of 350 Hv of KS B 0893, which means they have good hardness. In the impact test, all results were larger than the KS reference value of 27J. In the macro test, they showed uniform structure state by the shape of the weld, and there was risk of lamination because no internal defects, bubbles, or impurities were found on the surface of the weld.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.171-176
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• 2004

Electro chemical corrosion tests were conducted on two structural steels, SS400 and SM490A, in various solutions with different pH values, All materials showed typical active corrosion behaviors in the solutions, and corrosion potential and current density were measured from the slopes obtained from the Tafel curves using linear polarization method. Corrosion potential increased in the acidic region and then decreased depending on the pH values of the solutions. All materials showed the fast corrosion rate in artificial acid rain(pH=4.7), but the slower corrosion rate was observed in NaOH solution(pH=12.0) for SS400 and in distilled water(pH=7.0) for SM490A, respectively, which is thought to come from the difference in chemical composition of two alloys. Generally homogeneous corrosion occurred in acid rain condition, and almost no corrosion was observed in distilled water in both alloys. NaOH solution produced more corrosion than distilled water, and more corrosion had progressed in SS400 than in SM490A in $3.5\%$ NaCl solution.

• Journal of Welding and Joining
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• v.23 no.5
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• pp.20-24
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• 2005

Due to the difficulties associated with the supply of steel plates, hot rolled coil (Steel grade: SM490A) is considered fur structural materials in replace of the existing SWS50A-M1. However, it is found that SM490A exhibits a significant anisotropy in terms of impact energy with respect to transverse and longitudinal directions. In this study, an experimental investigation is carried out to examine the relationship between the anisotropy in impact values and the fatigue strengths of SM490A with respect to the rolling direction of test specimens. All test specimens failed around 1,500,000 cycles regardless of the test specimen direction. Therefore, it is found that the anisotropy in impact energy is not related to the fatigue strength of the materials considered in this study. However, the transverse direction specimen showed more rapid brittle fracture mode compared to that of longitudinal direction specimen, and this appears to be related to the lower impact values in transverse direction.

• Fire Science and Engineering
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• v.27 no.5
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• pp.1-7
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• 2013

Fire at building can occur enormous damages to life, properties, and environment and the risk of fire breakout is going up higher because of application of combustible materials than before. Therefore, the steel industries are trying to develop fire resistant steel in order to sustain the load bearing capacity of steel structures during fire situation. In this paper, to give the basis data-bases for evaluation of structural stability of steel structures applied fire resistant steel, FR 490, the tests of mechanical and thermal properties at high temperature were conducted and the comparisons are done with the SM 490 that has the same mechanical one.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.146-153
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• 2004

We compared the fatigue characteristics of weld metal with those of base metal, and not heat-treated with heat-treated. Also, we examined the influence of bead in a viewpoint of fatigue life. From the experimental results, it has been seen that the fatigue characteristics of welded specimens grinded the toe of bead are slightly better than not grinded. We have seen that the fatigue life is affected more by the stress concentration on the profile change in the weld toe rather than by residual stress influence, because heat-treated or not had almost no influence on the fatigue characteristics.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.859-864
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• 2004

In this study, we compared the fatigue characteristics of weld metal with those of base metal. Also we examined the influence of heat treatment and weld bead profiles for the fatigue life of weld metals. From the experimental results, it was seen that the fatigue characteristics of welded specimens with a grinded toe of bead are slightly better than those are not grinded. Also the fatigue life is affected more by the stress concentration on the profile change in the weld toe rather than by residual stress influence, because the fatigue characteristic of weld metals was not influenced whether the heat treatment is conducted or not.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.5
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• pp.80-86
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• 2005

High velocity oxy-fuel thermally sprayed coating of the WC-Co cermet material is a well-established process for modifying the surface properties of the structural components exposed to the corrosive and wear attacks. The hard WC phase in the coating resists to the wear while the soft metallic Co increases the adhesive and cohesive bonding properties. The coating properties deposited by the HVOF process are greatly dependent on the feedstock materials and processing parameters. The effects of the feedstock material and process coating parameters including the in-flight particle parameters and resultant coating microstructures were observed in this paper.