• Title/Summary/Keyword: IF Steel Sheet

Search Result 42, Processing Time 0.025 seconds

A Study on the Shear Strengthening Effect of Reinforced Concrete Beams with Structural Damage (구조적 손상을 입은 철근콘크리트 보의 전단보강 효과에 관한 연구)

  • Shin, Yong-Seok;Kim, Jeong-Hoon;Kim, Jeong-Sup;Kim, Kwang-Seok;Cho, Cheol-Hee
    • Journal of the Korea Institute of Building Construction
    • /
    • v.8 no.5
    • /
    • pp.43-51
    • /
    • 2008
  • This study examines shear capacity performance and structural characteristics of reinforced concrete beam using carbon fiber sheet(CFS), g)ass fiber sheet(GFS), glass fiber steel plate(GSP) and carbon fiber bar CB) which are reinforcing materials for reinforced concrete beam in order to produce similar condition to repair and reinforce actual structure and aims to provide data available In designing and constructing reinforced concrete structures under the structural damage. This study obtains the following conclusions. After considering the shear experiment results. it was indicated that the CB reinforced test object was the best in the shear capacity improvement and ductility capacity as it was contained in the concrete and was all operated, Also, GFS reinforced test object indicated the reduced flexural capacity but good shear capacity. GSP reinforced test object had bigger reinforcing strength than other reinforcing test objects. On the other hand, it showed the lowest reinforcement effect as compared section thickness of reinforced material because it showed the bigger relativity a section thickness of reinforced material. If the adherence to the concrete is improved, it will seem to show bigger reinforcement effect.

Microstructural Evolution with Annealing of Ultralow Carbon IF Steel Severely Deformed by Six-Layer Stack ARB Process (6층겹침ARB공정에 의해 강소성가공된 극저탄소IF강의 어닐링에 따른 미세조직 변화)

  • Lee, Seong-Hee
    • Korean Journal of Materials Research
    • /
    • v.22 no.8
    • /
    • pp.403-408
    • /
    • 2012
  • A sample of ultra low carbon IF steel was processed by six-layer stack accumulative roll-bonding (ARB) and annealed. The ARB was conducted at ambient temperature after deforming the as-received material to a thickness of 0.5 mm by 50% cold rolling. The ARB was performed for a six-layer stacked, i.e. a 3 mm thick sheet, up to 3 cycles (an equivalent strain of ~7.0). In each ARB cycle, the stacked sheets were, first, deformed to 1.5 mm thickness by 50% rolling and then reduced to 0.5 mm thickness, as the starting thickness, by multi-pass rolling without lubrication. The specimen after 3 cycles was then annealed for 0.5 h at various temperatures ranging from 673 to 973 K. The microstructural evolution with the annealing temperature for the 3-cycle ARB processed IF steel was investigated in detail by transmission electron microscopy observation. The ARB processed IF steel exhibited mainly a dislocation cell lamella structure with relatively high dislocation density in which the subgrains were partially observed. The selected area diffraction (SAD) patterns suggested that the misorientation between neighboring cells or subgrains was very small. The thickness of the grains increased in a gradual way up to 873 K, but above 898 K it increased drastically. As a result, the grains came to have an equiaxed morphology at 898 K, in which the width and the thickness of the grains were almost identical. The grain growth occurred actively at temperatures above 923 K.

Influence of Selective Oxidation Phenomena in CGLs on Galvanized Coating Defects Formation

  • Gong, Y.F.;Birosca, S.;Kim, Han S.;De Cooman, B.C.
    • Corrosion Science and Technology
    • /
    • v.7 no.1
    • /
    • pp.1-5
    • /
    • 2008
  • The gas atmosphere in continuous annealing and galvanizing lines alters both composition and microstructure of the surface and sub-surface of sheet steel. The formation and morphology of the oxides of alloying elements in High Strength Interstitial Free (HS-IF), Dual Phase (DP) and Transformation-Induced Plasticity (TRIP) steels are strongly influenced by the furnace dew point, and the presence of specific oxide may result in surface defects and bare areas on galvanized sheet products. The present contribution reviews the progress made recently in understanding the selective formation of surface and subsurface oxides during annealing in hot dip galvanizing and conventional continuous annealing lines. It is believed that the surface and sub-surface composition and microstructure have a pronounced influence on galvanized sheet product surface quality. In the present study, it is shown that the understanding of the relevant phenomena requires a combination of precise laboratory-scale simulations of the relevant technological processes and the use of advanced surface analytical tools.

A Development of Longitudinal and Transverse Springback Prediction Model Using Artificial Neural Network in Multipoint Dieless Forming of Advanced High Strength Steel (초고강도 판재 다점성형공정에서의 인공신경망을 이용한 2중 곡률 스프링백 예측모델 개발)

  • Kwak, M.J.;Park, J.W.;Park, K.T.;Kang, B.S.
    • Transactions of Materials Processing
    • /
    • v.29 no.2
    • /
    • pp.76-88
    • /
    • 2020
  • The need for advanced high strength steel (AHSS) forming technology is increasing as interest in light weight and safe automobiles increases. Multipoint dieless forming (MDF) is a novel sheet metal forming technology that can create any desired longitudinal and transverse curvature in sheet metal. However, since the springback phenomenon becomes larger with high strength metal such as AHSS, predicting the required MDF to produce the exact desired curvature in two directions is more difficult. In this study, a prediction model using artificial neural network (ANN) was developed to predict the springback that occurs during AHSS forming through MDF. In order to verify the validity of model, a fit test was performed and the results were compared with the conventional regression model. The data required for training was obtained through simulation, then further random sample data was created to verify the prediction performance. The predicted results were compared with the simulation results. As a result of this comparison, it was found that the prediction of our ANN based model was more accurate than regression analysis. If a sufficient amount of data is used in training, the ANN model can play a major role in reducing the forming cost of high-strength steels.

The Case Study of Design on Steel Pipe Sheet Pile for Earth Retaining Wall on Deep Excavation (대심도 지반굴착을 위한 벽강관말뚝 흙막이공법의 설계 사례 연구)

  • Byung-Il Kim;Jong-Ku Lee;Kyoung-Tae Kim;Kang-Han Hong;Sang-Jae Han
    • Journal of the Korean Geosynthetics Society
    • /
    • v.22 no.1
    • /
    • pp.53-66
    • /
    • 2023
  • In this study, the results of the elasto-plastic beam analysis, finite element analysis and optimization design of the steel pipe sheet pile applied as an earth retaining wall under the deep excavation were presented. Through this study, it was found that the high-strength and sea resistant steel pipe has high allowable stress, excellent structural properties, favorable corrosion, and high utilization as an earth retaining wall, and the C-Y type joint has significantly improved the tensile strength and stiffness compared to the traditional P-P type. In addition, it was investigated that even if the leak or defect of the wall occurs during construction, it has the advantage of being able to be repaired reliably through welding and overlapping. In the case of steel pipe wall, they were evaluated as the best in views of the deep excavation due to the large allowable bending stress and deformation flexibility for the same horizontal displacement than CIP or slurry wall. Elasto-plastic and finite element analysis were conducted in consideration of ground excavation under large-scale earth pressure (uneven pressure), and the results were compared with each other. Quantitative maximum value were found to be similar between the two methods for each item, such as excavation behavior, wall displacement, or member force, and both analysis method were found to be applicable in design for steel pipe sheet pile wall. Finally, it was found that economical design was possible when determining the thinnest filling method with concrete rather than the thickest hollow shape in the same diameter, and the depth (the embedded length through normality evaluation) without rapidly change in displacement and member force.

A Study on the Improvement of Formability of Stainless Steel Sheets (스테인리스 판재의 성형성 향상에 관한 연구)

  • Bae, Won-Byeong;Heo, Byeong-U;Kim, Ho-Yun;Han, Jeong-Yeong
    • Transactions of Materials Processing
    • /
    • v.7 no.5
    • /
    • pp.445-449
    • /
    • 1998
  • In order to obtain optimum process variables during the drawing of stainless steel sheets rectangular cup drawing tests were carried out with several technically available stainless steel sheets. As parameters on testing materials for die and punches lubrication and blank holding forces were selected. Testing parameters played an important role if the deformed material was thin. Effect of material properties on the deformation behaviors was also discussed by using testing parameters selected in this experiment. From the test results we suggest the appropriate conditions to be applicable to the actual manufacturing processes

  • PDF

Selective Surface Oxidation of 590MPa TRIP Steel and Its Effect on Hot-Dip Galvanizability (590 MPa TRIP강의 선택적 표면산화 거동과 표면 산화막이 도금특성에 미치는 영향)

  • Kim, Seong-Hwan;Im, Jun-Mo;Huh, Joo-Youl;Lee, Suk-Kyu;Park, Rho-Bum;Kim, Jong-Sang
    • Korean Journal of Metals and Materials
    • /
    • v.49 no.4
    • /
    • pp.281-290
    • /
    • 2011
  • In order to gain better understanding of the selective surface oxidation and its influence on the galvanizability of a transformation-induced plasticity (TRIP) assisted steel containing 1.5 wt.% Si and 1.6 wt.% Mn, a model experiment has been carried out by depositing Si and Mn (each with a nominal thickness of 10 nm) in either monolayers or bilayers on a low-alloy interstitial-free (IF) steel sheet. After intercritical annealing at $800^{\circ}C$ in a $N_2$ ambient with a dew point of $-40^{\circ}C$, the surface scale formed on 590 MPa TRIP steel exhibited a microstructure similar to that of the scale formed on the Mn/Si bilayer-coated IF steel, consisting of $Mn_{2}SiO_{4}$ particles embedded in an amorphous $SiO_{2}$ film. The present study results indicated that, during the intercritical annealing process of 590 MPa TRIP steel, surface segregation of Si occurs first to form an amorphous $SiO_{2}$ film, which in turn accelerates the out-diffusion of Mn to form more stable Mn-Si oxide particles on the steel surface. During hot-dip galvanizing, particulate $Fe_{3}O_{4}$, MnO, and Si-Mn oxides were reduced more readily by Al in a Zn bath than the amorphous $SiO_{2}$ film. Therefore, in order to improve the galvanizability of 590 TRIP steel, it is most desirable to minimize the surface segregation of Si during the intercritical annealing process.

Effects of Alloy Additions and Annealing Parameters on Microstructure in Cold-Rolled Ultra Low Carbon Steels (극저탄소 냉연강판에서 합금원소 및 어닐링조건이 미세조직에 미치는 영향)

  • Jeong, Woo Chang
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.17 no.2
    • /
    • pp.78-86
    • /
    • 2004
  • Effects of the annealing parameters on the formation of ferrites transformed at low temperatures were studied in cold-rolled ultra low carbon steels with niobium and/or chromium. Niobium and chromium were found to be effective in the formation of the low temperature transformation ferrites. The low temperature transformation ferrites more easily formed when both higher annealing temperature and longer annealing time, allowing substitutional alloying elements to distribute between phases, are in combination with faster cooling rate. It was found from EBSD study that the additions of niobium or chromium resulted in the increase in the numbers of high angle grain boundaries and the decrease in those of the low angle grain boundaries in the microstructures. Both granular bainitic ferrite and bainitic ferrite were characterized by the not clearly etched grain boundaries in light microscopy because of the low angle grain boundaries.

A Study on Joining of Aluminum and Advanced High Strength Steel Using Friction Stir Hole Clinching (마찰교반 홀 클린칭을 이용한 알루미늄과 고장력강의 접합에 관한 연구)

  • Gao, L.H.;Kang, G.S.;Lee, K.;Kim, B M.;Ko, D.C.
    • Transactions of Materials Processing
    • /
    • v.26 no.6
    • /
    • pp.348-355
    • /
    • 2017
  • In recent years, dissimilar materials such as aluminum, magnesium, titanium, and advanced high strength steel are widely used in automotive body due to environment concerns and fuel consumption. Therefore, joining technology is important for assembling components made of dissimilar materials. In this study, friction stir hole clinching (FSHC) was proposed as a new mechanical joining method to join dissimilar materials. This process stirs and heats the upper sheet, forming mechanical interlocking with the lower sheet. The feasibility of this FSHC process was verified by comparing cross-section of joint in FSHC and hole clinching process under the same processing condition. Taguchi method was also applied to the FSHC process to estimate the effect of process parameters on joint strength and obtain optimal combination of process parameters. Joint strength of FSHC with optimal process condition was compared to that of FSHC with initial process condition as well as that of hole clinching with optimal process condition. Results showed that the FSHC process was useful for joining dissimilar materials, even if the formability of materials was low.

Influence of Stripping and Counter Punching Forces on Fine Blanking Characteristics of T-shaped Products (T형 제품의 파인 블랭킹 가공 특성에 미치는 스트리핑력과 카운터 펀칭력의 영향)

  • Kim, J.H.;Ryu, J.G.;Sim, K.S.;Kim, D.H.;Chang, Y.D.;Lee, J.H.
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.14 no.6
    • /
    • pp.15-21
    • /
    • 1997
  • This study is performed for investigating the effects of stripping and counter punching forces on shearing characteristics in fine blanking of T-shaped products, such as camber, burr-height and dimensional accuracy, etc by experiments. Conventional hydraulic press is used for experiments so that both the stripping force and counter punching force can be arbitrarily adjusted by another hydraulic unit connected to the fine blanking die. Specimens are selected as hot rolled steel sheet and carbon steel sheet commonly used in auto- mobile company. Based on the experimental results, both the dimensional accuracy and the burr height are not influenced by the stripping and counter punching forces, wherease the camber height representing dish- shaped deflection is much influenced by them, it can be seen through this study that the finely cut surface of T-shaped blank can be obtained even in conventional hydraulic press if additional equipments and specially designed die are employed.

  • PDF