• Title, Summary, Keyword: low-carbon steel

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Effect of the Arc Furnace Manufacturing Process, Blast Furnace Manufacturing Process, and Carbon Content on the High-temperature Oxidation of Hot-rolled Steel between 650 and 900℃ (열간 압연강의 600~900℃에서의 고온산화에 미치는 전기로제조법, 고로제조법 및 탄소량의 영향)

  • Kim, Min Jung;Lee, Dong Bok;Baek, Seon-Pil
    • Korean Journal of Metals and Materials
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    • v.48 no.10
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    • pp.907-913
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    • 2010
  • Hot-rolled steel plates of SPHC and SS400 were oxidized at 600, 750 and $900^{\circ}C$ for 2 hr in air. With an increase in the oxidation temperature, their oxidation rates increased, and this was accompanied by the formation of pores and cracks in the thickened oxide scales, which were non-adherent. SPHC steels manufactured by either an arc furnace or a blast furnace displayed similar oxidation rates, indicating that their oxidation rates were insensitive to the manufacturing process. Medium-carbon SS400 steel displayed somewhat faster oxidation rates than low-carbon SS400 steel, indicating that the carbon content did not significantly influence the oxidation rates.

High power $CO_2$ laser beam welding for low carbon steels (저탄소강의 고출력 $CO_2$ 레이저 빔 용접)

  • 김재도
    • Journal of Welding and Joining
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    • v.7 no.4
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    • pp.12-21
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    • 1989
  • Laser beam welding parameters have experimentally investigated, using a continuous wave 3kW $CO_2$ laser with the various travel speeds, beam mode and laser beam power in low carbon steels. An optimum position of focus and the effect of shielding gas on penetration depth with varying the flow range of 0.5 to 5.1m/min have been combined to investigate the effect of laser power and travel speed on penetration depth and bead width. It is found that the optimum position of focus in 3kW class laser is 0.5 to 1.5mm below the surface of the material. The flow rate of shielding gas affects the penetration depth and He is more effective than Ar. The penetration depth in laser welds of low carbon steels is between two and four times of the bead width. Laser beam welding of butt joints in 2mm thick carbon steel has been carried out to establish a weldability lobe. The lobe indicating acceptable welding conditions is introduced.

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Dilatometry Analysis of Low Carbon Steel considering Transformation Mismatch Plasticity (변태소성을 고려한 저탄소강 상변태의 Dilatometry 해석)

  • Suh D. W.;Oh C. S.;Kim S. J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.332-335
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    • 2005
  • A model is developed to quantitatively analyze the dilatometry curve of carbon steel for the evaluation of phase fraction during transformation. The effect of anisotropic volume change due to transformation mismatch plasticity as well as carbon enrichment in austenite during the transformation is considered in the developed model. The developed model is applied for the analysis of dilatometry curves of carbon steels. The result shows that considering the anisotropic dilatation is very essential to quantitatively evaluate the phase fraction from the dilatation curve.

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$Co_2$ Corrosion Mechanism of Carbon Steel in the Presence of Acetate and Acetic Acid

  • Liu, D.;Fu, C.Y.;Chen, Z.Y.;Guo, X.P.
    • Corrosion Science and Technology
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    • v.6 no.5
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    • pp.227-232
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    • 2007
  • The corrosion behavior of carbon steel (N80) in carbon dioxide saturated 1%NaCl solution with and without acetic acid or acetate was investigated by weight-loss test, electrochemical methods (polarization curve, Electrochemical impedance spectroscopy). The major objective is to make clear that the effect of acetic acid and acetate on the corrosion of carbon steel in $Co_2$ environments. The results indicate that either acetic acid or acetate accelerates cathodic reducing reaction, facilitates dissolution of corrosion products on carbon steel, and so promotes the corrosion rate of carbon steel in carbon dioxide saturated NaCl solution. All Nyquist Plots are consisting of a capacitive loop in high frequency region, an inductive loop in medial frequency region and a capacitive arc in low frequency region. The high frequency capacitive loop, medial frequency inductive loop and low frequency capacitive arc are corresponding to the electron transfer reaction, the formation/adsorption of intermediates and dissolution of corrosion products respectively. All arc of the measured impedance reduced with the increase of the concentration of Ac-, especially HAc. However, the same phenomenon is not notable after reducing pH value by adding HCl. HAc is a stronger proton donor and can be reduced directly by electrochemical reaction firstly. Ac- can't participate in electrochemistry reaction directly, but $Ac^-$ an hydrate easily to create HAc in carbon dioxide saturated environments. HAc is as catalyst in $Co_2$ corrosion. As a result, the corrosion rate was accelerated in the presence of acetate ion even pH value of solution increased.

Chip Forming Characteristics of Bi-S Free Machining Steel (Bi-S 쾌삭강의 칩생성특성)

  • 이영문
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.351-356
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    • 1999
  • In this study, the characteristics of chip formation of the cold drawn Bi-S free machining steels were assessed. And for comparison, those of the cold drawn Pb-S free machining steel, the hot rolled low carbon steel which has MnS as free machining inclusions and the conventional steels were also investigated. During chip formation, the cold drawn free machining steels show relatively little change in thickness and width of chip compare to those of the conventional carbon steels. And a single parameter which indicates the degree of deformation during chip formation, 'chip cross-section area ratio' is introduced. The chip cross-section area. The variational patterns of cross-section area is divided by undeformed chip cross-section area. The variational patterns of the chip cross-section area ratio of the materials cut are similar to those of the shear strain values. The shear stress, however, seems to be dependent on the carbon content of the materials. The cold drawn BiS and Pb-S steels show nearly the same chip forming behaviors and the energy consumed during chip formation is almost same. A low carbon steel without free machining aids shows poor chip breakability due to its high ductility. By introducing a small amount of non-metallic inclusions such as MnS, Bi, Pb or merely increasing carbon content the chip breakability improves significantly.

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Chip Forming Characteristics of Bi-S Free Machining Steel (Bi-S 쾌삭강의 칩생성특성)

  • 조삼규
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.9 no.3
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    • pp.48-54
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    • 2000
  • In this study the characteristics of chip formation of the cold drawn Bi-S free machining steels were assessed. And for comparison those of the cold drawn Pb-S free machining steel the hot rolled low carbon steel which has MnS as free machining inclusions and the conventional steels were also investigated. During chip formation the cold drawn free machining steels show relatively little change in thickness and width of chip compare to those of the conventional carbon steels. And a single parameter which indicates the degree of deformation during chip formation chip cross-section area ratio is introduced. The chip cross-section area ratio is defined as chip cross-section area is divided by undeformed chip cross-section area. The variational patters of the chip cross-section area ratio of the materials cut are similar to those of the shear strain values. The shear stress however seems to be dependent on the carbon content of the materials. The cold drawn Bi-S and Pb-S steels show nearly the same chip forming behaviors and the energy consumed during chip formation is almost same. A low carbon steel without free machining aids shows poor chip breakability due to its high ductility. By introducing a small amount of free machining inclusions such as MnS Bi, Pb or merely increasing carbon content the chip breakability improves significantly.

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Effect of Aluminum and Solute N on the Strain Aging of Extremely Low-Carbon Automotive Steel Strengthened with Cu sulfide (초극저탄소 Cu강화형 자동차용 강판 변형시효에 미치는 Aluminum 및 고용질소의 영향)

  • Hong, Moon-Hi;Yang, Hye-mi;Song, Seung-Woo;Han, Seong-Ho
    • Korean Journal of Metals and Materials
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    • v.47 no.2
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    • pp.71-78
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    • 2009
  • The precipitation behavior of solute carbon and nitrogen strongly affects the mechanical properties of low-carbon automotive panel. In the present study, the effects of aluminum and solute nitrogen on the bake hardenability and strain aging of extremely low-carbon steel with carbon content below 15 ppm has been investigated. The ferrite grain size and distribution of precipitates were varied with the amount of aluminum content of 0.003 to ~ 0.100 wt% in a constant solute carbon and nitrogen. With increasing the aluminum content, the ferrite grain size is increased and strain aging is delayed. The strain aging is also delayed by increasing the annealing temperature, although the ferrite grain size is not much changed.

Design of Innovative SMA PR Connections Between Steel Beams and Composite Columns (강재보와 합성기둥에 사용된 새로운 반강접 접합부의 설계)

  • Son, Hong Min;Leon, Roberto T.;Hu, Jong Wan
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.5 no.1
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    • pp.28-36
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    • 2014
  • This study describes the development of innovative connections between steel beams and concrete-filled tube columns that utilize a combination of low-carbon steel and super-elastic shape memory alloy components. The intent is to combine the recentering behavior provided by the shape memory alloys to reduce building damage and residual drift after a major earthquake with the excellent energy dissipation of the low-carbon steel. The analysis and design of structures requires that simple yet accurate models for the connection behavior be developed. The development of a simplified 2D spring connection model for cyclic loads from advanced 3D FE monotonic studies is described. The implementation of those models into non-linear frame analyses indicates hat the recentering systems will provide substantial benefits for smaller earthquakes and superior performance to all-welded moment frames for large earthquakes.

Analysis on the Mechanism of Fluting in the Bending of Low Carbon Steel Sheets (저탄소강판을 이용한 굽힘 가공에서 발생하는 꺽임현상에 대한 발생 기구 해석)

  • Park, K.C.;Yoon, J.B.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.336-339
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    • 2007
  • In order to investigate the cause of fluting in tangential bending of low carbon steel sheet, an analytic analysis, an experiment and a series of finite element analysis for bending process were done. The fluting in bended sheet was due to the yield point elongation of material. Due to the yield point elongation, unstable plastic hinge was occurred in course of bending of elastic perfectly plastic sheet. According to the analysis and computational results, lower yield point elongation than 5% was required to prevent fluting in $0.5{\sim}0.6t$ sheet in $15{\sim}20mm$ radius bending.

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The Effect of Structure on the Fatigue of Low Carbon Steel (조직변화(組織變化)가 피로현상(疲勞現象)에 미치는 영향(影響))

  • C.S.,Kang;C.M.,Suh
    • Bulletin of the Society of Naval Architects of Korea
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    • v.9 no.2
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    • pp.33-42
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    • 1972
  • This paper was studied on the behavior, crack formation and propagation of slip bands on low carbon steel which was heat-treated in three conditions in order to change metallic structure. The specimens were tested by rotating bending fatigue testing machine and also observed the variations of grains by microscope. From the test results it was clear that fatigue endurance limit and life of low carbon steel were more increased in contrast with the case that the grain size of specimen was more decreased. Slip bands developed at oil-quenched specimen and furnace-cooled specimen. Formed cracks in the first one or two grains below the surface were approximately "planar" type, there after they followed "wavy" type. It was also found that cracks at 30% higher stress than fatigue limit were usually developed inter-granular, and cracks at 12% higher stress than fatigue limit were propagated meandering path, partly trans- and partly inter-grandular.

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