• Title/Summary/Keyword: Hot-Cold

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Mechanical Property Variations of the Strip in the Skin Pass Process after Hot Rolling (열연 강판의 정정공정에 따른 재질변화 예측기술)

  • Lee, J.H.;Kim, H.J.;Kim, J.M.;Lee, J.K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.10a
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    • pp.211-214
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    • 2008
  • The Mechanical properties of steel in hot strip mill were associated with the various rolling conditions such as alloy composition, plastic deformation, cooling history and so on. After coiling process of strip which is the end of hot rolling process, the coil can be the final product or can be applied by another process, that is, cold rolling or skin pass rolling with the additional changes of mechanical properties. Skin pass rolling process with the small reduction affects the mechanical properties of the strip. Because many kinds of hot strips are delivered to the customers after the skin pass process, it is important for us to know the skin pass effects for the mechanical properties of the hot rolling strip. In this study, the variations of mechanical properties of the strip after the skin pass rolling will be discussed. Then, the mathematical model will be proposed for the prediction of mechanical properties of the final products with the comparison between measured and calculated values.

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Analysis of Phase Transformation and Temperature History during Hot Stamping Using the Finite Element Method (유한요소해석을 이용한 핫스탬핑 공정시 발생하는 온도 이력 및 상변태 해석)

  • Yoon, S.C.;Kim, D.H.
    • Transactions of Materials Processing
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    • v.22 no.3
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    • pp.123-132
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    • 2013
  • Hot stamping, which is the hot pressing of special steel sheet using a cold die, can combine ease of shaping with high strength mechanical properties due to the hardening effect of rapid quenching. In this paper, a thermo-mechanical analysis of hot stamping using the finite element method in conjunction with phase transformations was performed in order to investigate the plastic deformation behavior, temperature history, and mechanical properties of the stamped car part. We also conducted a fully coupled thermo-mechanical analysis during the stamping and rapid quenching process to obtain the mechanical properties with the consideration of the effects of plastic deformation and phase transformation on the temperature histories at each point in the part. The finite element analysis could provide key information concerning the temperature histories and the sheet mechanical properties when the phase transformation is properly considered. Such an analysis can also be used to determine the effect of cyclic cooling on the tooling.

Study on an Aluminum Modified Alloy and Manufacturing Conditions for Hot Metal Gas Forming (열간가스성형용 알루미늄 개발 합금 공정 조건에 관한 연구)

  • Lee, G.M.;Go, G.Y.;Lee, H.C.;Kim, D.O.;Lee, Y.K.;Kim, J.S.;Song, J.H.
    • Transactions of Materials Processing
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    • v.26 no.4
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    • pp.222-227
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    • 2017
  • In order to respond to environmental regulations and increased demand for fuel economy, the demand for lightweight car bodies has grown. Hydroforming of aluminum is one possible solution as it eliminates the need for additional welding to develop closed cross-sectional parts. However, the low formability of aluminum is a limitation of its application. On the other hand, the ductility of materials can be improved at higher temperatures, and hot metal gas forming has been widely applied in the production of lightweight vehicle parts. In this study, aluminum alloy for pipe extrusion was developed by controlling the Mg:Cr:Mn ratio based on AA5083. Mechanical properties of the developed material were examined by tensile test and were applied to a forming simulation. Cold forming simulation for preforming and non-isothermal hot forming simulation for hot metal gas forming were carried out to validate process conditions. A prototype of the sidemember was manufactured under the given process condition. Finally, thickness distribution was compared with finite element analysis results.

A literature study on cancer therapy of warm-hot oriental medicine (암(癌)의 온열약물(溫熱藥物) 치료법(治療法)에 대(對)한 고찰(考察))

  • Cho, Chin-Ho;Son, Chang-Gyu;Cho, Chong-kwan
    • Journal of Haehwa Medicine
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    • v.9 no.2
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    • pp.223-239
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    • 2001
  • A literature study on cancer therapy of warm-hot oriental medicine was done, and the results were as follows. 1. In oriental medicine, oncogens are six exopathogens, seven modes of emotion, overwork, pathogenic factors, and especially related with pathologic cold situation. 2. There are many capillaries in tuomr, and because temperature of inner space of tumor is higher than normal organization. Tumor cell has a character which is weak for high temperature. 3. Warm-hot herb drugs have effects of dissipating mass, warming kidney to reinforce yang and dispering, so it has a function of suppressing tumor as well as improving immunity in cancer therapy. 4. In traditional medical books, main prescriptions of cancer therapy are xinzhiyinyanggongjiwan(新製陰陽攻積丸), qianjinxiaoshiwan(千金硝石丸), feiqiwan(肥氣丸), xibenwan(息賁丸), fuliangwan(伏梁丸), beiqiwan, bentunwan(賁豚丸), zengsunwujiwan(增損五積丸), and these are composed of warm-hot herb drugs. 5. In current, the study of warm-hot drugs is progressed in immunological capacity, anti-tumor activity, stimulating bone marrow and regulating hormone secretion. It will be expected that advanced study of these must be accomplished in cancer patients.

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Experimental Study on Thermoelectric Generator Performance for Waste Heat Recovery in Vehicles (자동차 배기폐열 회수용 열전발전 시스템의 성능에 관한 연구)

  • Lee, Dae-Woong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.6
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    • pp.287-293
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    • 2014
  • Internal combustion engines release 30~40% of the energy from fossil fuels into the atmosphere in the form of exhaust gases. By utilizing this waste heat, plenty of energy can be conserved in the auto industry. Thermoelectric generation is one way of transforming the energy from engine's exhaust gases into electricity in a vehicle. The thermoelectric generators located on the exhaust pipe have been developed for vehicle applications. Different experiments with thermoelectric generators have been conducted under various test conditions as following examples: hot gas temperature, hot gas mass flow rate, coolant temperature, and coolant mass flow rate. The experimental results have shown that the generated electrical power increases significantly with the temperature difference between the hot and the cold side of the thermoelectric generator and the gas flow rate of the hot-side heat exchanger. In addition, the gas temperature of the hot-side heat exchanger decreases with the length of the thermoelectric generator, especially at a low gas flow rate.