• 제목/요약/키워드: Steel Base

검색결과 1,060건 처리시간 0.027초

소규모 철골조건축물 강축방향 노출형 주각부의 내진성능 향상을 위한 실험 연구 (Experimental Study on Seismic Performance Enhancement of Exposed Column-base Plate Strong-axis Connections for Small-Sized Steel Buildings)

  • 유영찬
    • 대한건축학회논문집:구조계
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    • 제34권12호
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    • pp.11-20
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    • 2018
  • The purpose of this study is to investigate the seismic performance of exposed column-base plate strong-axis connections for small-sized steel buildings. Even though the seismic design for small-sized buildings became mandatory since Dec.2017, the arbitrary connection details in steel structure have been applied at the construction site, which is considered to be very insufficient to secure structural safety and stability considering the increased seismic risk. Therefore, a series of experimental test programs had been carried out to develop enhanced connection details in order to ensue the adequate seismic safety of small buildings. The hysteretic behavior of the exposed column-base plate connections commonly used in Korea seem to be very pure poor due to the "Rocking" phenomena between anchor plate and concrete by the residual plastic deformation of anchor bolts. A series of hysteretic tests were conducted to find the solution to overcome the "Rocking" phenomena of the exposed column-base plate connections, finally the stable seismic behavior was obtained by uisng at least 8 anchor bolts with good bonding strength to the protptype specimen.

탄소강 용접접합부의 모재블록전단내력에 관한 실험적 연구 (An Experimental Study on Block Shear Strength of Carbon Steel Fillet Welded Connection with Base Metal Fracture)

  • 이화영;황보경;이후창;김태수
    • 대한건축학회논문집:구조계
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    • 제34권1호
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    • pp.11-18
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    • 2018
  • An experimental study on the ultimate behaviors of the mild carbon steel (SPHC) fillet-welded connection is presented in this paper. Seven specimens were fabricated by the shielded metal arc welding (SMAW). All specimens failed by typical block shear fracture in the base metal of welded connections not weld metal. Block shear fracture observed in the base metal of welded connection is a combination of single tensile fracture transverse to the loading direction and two shear fractures longitudinal to the loading direction. Test strengths were compared with strength predictions by the current design equations and suggested equations by previous researchers. It is known that current design specifications (AISC2010 and KBC2016) and Oosterhof & Driver's equation underestimated overly the ultimate strength of the welded connection by on average 44%, 31%, respectively and prediction by Topkaya's equation was the closest to the test results. Consequently, modified equation is required to be proposed considering the stress triaxiality effect and material property difference on the block shear strength for base metal fracture in welded connections fabricated with mild carbon steel.

Corrosion Inhibition Studies on Low Carbon Steel in Hydrochloric Acid Medium Using o-Vanillin-Glutamine Schiff Base

  • Thusnavis, G. Rexin;Archana, T.V.;Palanisamy, P.
    • Corrosion Science and Technology
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    • 제21권1호
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    • pp.32-40
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    • 2022
  • The o-Vanillin - Glutamine Schiff base [2-Hydroxy-3-Methoxy BenzylidineCarbomyl) -2-Butanoic Acid] was examined for low carbon steel corrosion inhibition in acid media. Weight loss studies were carried out at three different temperatures to determine the inhibition efficiency (IE). Electrochemical impedance spectroscopy revealed that the charge transfer resistance controlled the corrosion reaction and Tafel polarization indicated that the Schiff base acts as mixed mode of inhibitor. SEM images were recorded for the surface morphology of the low carbon steel surface. DFT studies revealed corrosion control mechanisms using quantum chemical parameters such as EHOMO, ELUMO, energy gap (∆E), chemical Hardness (η), chemical Softness (σ), Electronegativity (χ), and the fraction of electron transferred (∆N), which is calculated using Gaussian software 09. The gas-phase geometry was fully optimized in the Density Functional Theory (DFT/B3LYP-6-31G (d)).The DFT results are in good agreement with the experimental results. All the results proved that the Schiff Base (2-Hydroxy-3-Metoxy BenzylidineCarbomyl) -2-Butanoic is a suitable alternative for corrosion inhibition of low carbon steel in acid media.

Electrochemical corrosion study on base metals used in nuclear power plants in the HyBRID process for chemical decontamination

  • Kim, Sung-Wook;Park, Sang-Yoon;Roh, Chang-Hyun;Shim, Ji-Hyung;Kim, Sun-Byeong
    • Nuclear Engineering and Technology
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    • 제54권6호
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    • pp.2329-2333
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    • 2022
  • Base metal corrosion forms a significant issue during the chemical decontamination of the primary coolant loop in nuclear power plants as it is directly related to the economic and safety viability of decommissioning. In this technical note, potentiodynamic evaluations of several base metals (304 stainless steel, SA106 Grade B carbon steel, and alloy 600) were performed to determine their corrosion behavior during the hydrazine (N2H4)-based reductive ion decontamination (HyBRID) process. The results suggested that N2H4 protected the surface of the base metals in the HyBRID solution, which is primarily composed of H2SO4. The corrosion resistance of the carbon steel was further improved through the addition of CuSO4 to the solution. The corrosion rate of carbon steel in the H2SO4-N2H4-CuSO4 solution was lower than that exhibited in an oxalic acid solution, a commonly used reaction medium during commercial decontamination processes. These results indicate the superiority of the HyBRID process with respect to the base metal stability.

Vacuum Characteristic of a Chamber Made of Mild Steel

  • Park, Chongdo;Ha, Taekyun;Cho, Boklae
    • Applied Science and Convergence Technology
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    • 제24권4호
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    • pp.84-89
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    • 2015
  • The base pressure and outgassing rate of a mild steel chamber were measured and compared to those of a stainless steel chamber. A combined sputter-ion and non-evaporable getter pump with a nominal pumping speed of 490 l/s generated the base pressure of $2.7{\times}10^{-11}$ mbar in the mild steel chamber and $1.2{\times}10^{-10}$ mbar in the stainless steel chamber. The rate-of-rise measurements show that the mild steel has an extremely low outgassing rate of $2.6{\times}10^{-13}$ mbar $ls^{-1}cm^{-2}$, which is about one-order of magnitude smaller than the outgassing rate of the stainless steels. Vacuum annealing of the mild steel at $850^{\circ}C$ reduced the outgassing rate further to $8.8{\times}10^{-14}$ mbar $ls^{-1}cm^{-2}$, which was comparable to the outgassing rate of a heat treated stainless steel for extreme-high vacuum use.

TMCP 고장력강 용접부의 피로파양 특성에 관한 연구 (A study on the fatigue fracture characteristics of TMCP high tensile strength steel welds)

  • 김영식;노재충;한명수;김윤해
    • Journal of Advanced Marine Engineering and Technology
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    • 제12권1호
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    • pp.47-54
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    • 1988
  • TMCP steel manufactured by controlled rolling followed by accelerated cooling process is known to have extra-ordinary mechanical properties such as tensile strength and toughness. However, there is much uncertainty about the fatigue fracture characteristics of this steel. In this paper, the fatigue fracture behaviour of the TMCP steel in base metal and weldment were inspected through the Dynamic Implant test method. Those results were quantitavely compared with those of the ordinary normalized steel of same strength level. Moreover, the effect of the diffusible hydrogen included in the welded part on the fatigue fracture behaviour were made clear. As the experimental results, the fatigue fracture characteristics of the TMCP steel in case of base metal proved out to be superior to that of the normalized steel. However, the TMCP steel weldment including the diffusible hydrogen appeared to have inferior fatigue characteristics compared with the same conditioned normalized steel weldment.

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TIG 용접한 저방사화 페라이트강 (JLF-1)의 고온강도 및 피로수명특성 (High Temperature Tensile Strength and Fatigue Life Characteristics for Reduced Activation Ferritic Steel (JLF-1) by TIG Welding)

  • 윤한기;이상필;김사웅
    • 대한기계학회논문집A
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    • 제27권9호
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    • pp.1444-1450
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    • 2003
  • The fatigue life and tensile strength of JLF-1 steel (Fe-9Cr-2W-V-Ta) and its TIG weldment were investigated at the room temperature and $400^{\circ}C$. Four kinds of test specimens, which associated with the rolling direction and the TIG welding direction were machined. The base metal of JLF-1 steel represented almost anisotropy in the tensile properties for the rolling direction. And the base metal of JLF-1 steel showed lower strength than that of TIG weldment. Also, the strength of all materials entirely decreased in accordance with elevating test temperature. Moreover, the fatigue limit of weld metal was largely increase than that of base metal at both temperatures. The fatigue limit of JLF-1 steel decreased in accordance with elevating test temperature. The fatigue limit of JLF-1 steel decreased in accordance with elevating test temperature. The SEM fractography of tensile test specimen showed conspicuous cleavage fracture of a radial shape. In case of fatigue life test specimen, there were so many striations at crack initiation region, and dimple was observed at final fracture region as a ductile fracture mode.

탄소강-스테인리스강 용접부의 피로균열진전 특성에 관한 연구 (A Study on the Fatigue Crack Growth Characteristics for the Weldment of Carbon steel-Stainless steel)

  • 권재도;김우현;김길수;박중철;배용탁;김중형
    • Journal of Welding and Joining
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    • 제16권4호
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    • pp.47-54
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    • 1998
  • Various equipments in plants are welded with two different materials and it is required to investigate the effects of fatigue crack propagation on the neighborhood of a welded portion. The characteristics of fatigue crack growth in the base metal of carbon and stainless steel, in the carbon and stainless steel sides located in the neighborhood of welded portion (carbon/stainless steel), respectively and welded portion, are investigated. The results show that the crack growth in the welded portion (carbon/stainless steel) is an average value of the crack growths in the carbon and stainless steel respectively located in the neighborhood of the welded portion. It is found that the crack growth in the welded portion is not significantly different from those in the carbon and stainless steel sides. Hence it can be concluded that the structure welded with two different materials wold not impede the integrity based on the fatigue crack growth.

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Cu-Sn 삽입금속을 이용한 DP강의 아크 브레이징 접합부의 미세조직과 인장특성 (Microstructure and Tensile Strength Property of Arc Brazed DP steel using Cu-Sn Insert Metal)

  • 조욱제;조영호;윤중길;강정윤
    • Journal of Welding and Joining
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    • 제31권1호
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    • pp.58-64
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    • 2013
  • The following results were obtained, microstructures and tensile properties in arc brazed joints of DP(dual phase) steel using Cu-5.3wt%Sn insert metal was investigated as function of brazing current. 1) The Fusion Zone was composed of ${\alpha}Fe+{\gamma}Cu$ and Cu23Sn2. The reason for the formation of these solid solutions. Despite, Fe & Cu were impossible to solid solution at room temperature. It's melting & reaction to something of insert metal & Base Metal (DP Steel) by Arc. Brazing Process has faster cooling rate then Cast Process, Supersaturated solid solution at room temperature. 2) The increase Hardness of Fusion Zone was directly proportional to the rise of welding current. Because, ${\alpha}Fe+{\gamma}Cu$ phase (higher hardness than the Cu23Sn2.(104.1Hv < 271.9Hv)) Volume fraction was Growth, due to increasing the amount of base metal melting by High current. 3) The results of tensile shear test by Brazing, All specimens happen to fracture in Fusion Zone. On the other hand, when Brazing Current increasing tend to rise tensile load. but it was very small, about 26-30% of the base metal. 4) The result of fracture analysis, The crack initiate at Triple Point for meet to Upper B.M/Under B.M/Fusion Zone. This Crack propagated to Fusion zone. So ruptured by tensile strength. The Reason to in the fusion zone fracture, Fusion zone by Brazing of hardness (strength) was very lower then the base metal (DP steel). In addition the Fusion Zone's thickness in triple point was thin than the base metal's thickness in triple point.

On the numerical assessment of the separation zones in semirigid column base plate connections

  • Baniotopoulos, C.C.
    • Structural Engineering and Mechanics
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    • 제2권3호
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    • pp.295-309
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    • 1994
  • The present paper concerns the mathematical study and the numerical treatment of the problem of semirigid connections in bolted steel column base plates by taking into account the possibility of appearance of separation phenomena on the contact surface under certain loading conditions. In order to obtain a convenient discrete form to simulate the structural behaviour of a steel column base plate, the continuous contact problem is first formulated as a variational inequality problem or, equivalently, as a quadratic programming problem. By applying an appropriate finite element scheme, the discrete problem is formulated as a quadratic optimization problem which expresses, from the standpoint of Mechanics, the principle of minimum potential energy of the semirigid connection at the state of equilibrium. For the numerical treatment of this problem, two effective and easy-to-use solution strategies based on quadratic optimization algorithms are proposed. This technique is illustrated by means of a numerical application.