• Title/Summary/Keyword: rolling

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Effect of Asymmetric Hot Rolling on the Texture Evolution of Fe-3%Si Steel

  • Na, Tae-Wook;Park, Hyung-Ki;Park, Chang-Soo;Joo, Hyung-Don;Park, Jong-Tae;Han, Heung Nam;Hwang, Nong-Moon
    • Metals and materials international
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    • v.24 no.6
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    • pp.1369-1375
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    • 2018
  • In Fe-3%Si steel, the hot rolling process affects not only the hot rolling texture but also the primary recrystallization texture. Here, the effect of asymmetric hot rolling was studied by comparing the difference in the texture evolved between asymmetric and symmetric hot rolling. The effect of asymmetric hot rolling on the texture of primary recrystallized Fe-3%Si steel was also studied. The symmetric hot rolling of Fe-3%Si steel produces a rotated cube texture at the center but Goss and copper textures near the surface. Asymmetric hot rolling tends to produce Goss and copper textures even at the center like the texture near the surface. After primary recrystallization, the dominant texture at the center changes from {001} <210> to {111} <112> and the new texture has a higher fraction of the grains which make the low energy boundary with Goss grains than that of symmetric hot rolling.

Investigation of single bubble behavior under rolling motions using multiphase MPS method on GPU

  • Basit, Muhammad Abdul;Tian, Wenxi;Chen, Ronghua;Basit, Romana;Qiu, Suizheng;Su, Guanghui
    • Nuclear Engineering and Technology
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    • v.53 no.6
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    • pp.1810-1820
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    • 2021
  • Study of single bubble behavior under rolling motions can prove useful for fundamental understanding of flow field inside the modern small modular nuclear reactors. The objective of the present study is to simulate the influence of rolling conditions on single rising bubble in a liquid using multiphase Moving Particle Semi-implicit (MPS) method. Rolling force term was added to 2D Navier-Stokes equations and a computer program was written using C language employing OpenACC to port the code to GPU. Computational results obtained were found to be in good agreement with the results available in literature. The impact of rolling parameters on trajectory and velocity of the rising bubble has been studied. It has been found that bubble rise velocity increases with rolling amplitude due to modification of flow field around the bubble. It has also been concluded that the oscillations of free surface, caused by rolling, influence the bubble trajectory. Furthermore, it has been discovered that smaller vessel width reduces the impact of rolling motions on the rising bubble. The effect of liquid viscosity on bubble rising under rolling was also investigated and it was found that effects of rolling became more pronounced with the increase of liquid viscosity.

Elastic Wave Properties of STS316L with Different Rolling Temperature (가공 온도가 다른 STS316L의 탄성파 특성)

  • Tak, Young-Joon;Gu, Kyoung-Hee;Lee, Gum-Hwa;Nam, Ki-Woo
    • Journal of the Korean Society of Industry Convergence
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    • v.25 no.3
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    • pp.325-331
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    • 2022
  • In this study, austenitic 316L stainless steel was rolled at three different temperatures (100℃, -50℃, -196℃) at five rolling degree (0, 16, 33, 50, 66 and 80%). The rolled specimen was examined for micro structure, and the volume fraction and mechanical properties were evaluated. In particular, the rolling specimen detected the elastic wave generated in tensile and investigated the relationship between the rolling degree and the dominant frequency. As the rolling degree increased, austenite decreased and martensite increased. The volume fraction of martensite more increased at lower temperatures, but increased rapidly at the rolling degree of 50% of all rolling temperature. Tensile strength increased rapidly with the increase of the rolling degree, and was larger at lower temperatures. The elongation decreased sharply to the rolling degree of 33%, but decreased gently thereafter. The dominant frequency highly appeared as the volume fraction of martensite increased, but the dominant frequency was higher at the low temperature rolling temperature. A similar trend was also observed in the relationship between tensile strength and dominant frequency.

Fabrication of copper thin foils with 36 microns by cold rolling (냉간 압연 공정에 의한 두께 $36{\mu}m$ 동극박 제조 공정 해석)

  • Lee, S.H.;Kim, B.M.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.413-416
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    • 2007
  • In general, by means of the electrodepositing technique, a copper foil sample was prepared with a high purity and a high density. But the mechanical properties of the electrodepositing copper foil was lower than it's the rolling copper foil. However, the production of copper foil with approximately 36 microns thick in rolling process was very difficult. This paper describes the outline of the high accuracy cold rolling in 6 high mill which was developed for the purpose of rolling very thin accurate gauge copper foil(36 micron thick), and give several rolling characteristic of 600 mm wide copper foil. a) Large strain can be accumulated pass by pass in industrial multi-pass rolling processing to overcome large critical strain for thickness accuracy through optimization of rolling schedule. b) Also, permissible tension for rolling 0.45 $\sim$ 0.036 mm thick copper strip stably in accordance with the each pass work had been established by FEM simulation results. c) During the plate rolling process, considerable values of the forces of material pressure on the tool occur. These pressures cause the elastic deformation of the roll, thus changing the shape of the deformation region. A numerical simulation of roll deflection during cold rolling is presented in the paper. d) The proposed pass schedule can roll very thin copper foil of 36 micron thickness to a tolerance of ${\pm}1$ microns. The validity of simulated results was verified into rolling experiments on the copper foil.

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Prediction of Three-Dimensional Strip Profile for 6-High Mill in Thin-Strip Rolling (6 단 압연기의 극박 압연공정에서 3 차원 판 형상 예측)

  • Lee, Sang-Ho;Song, Gil-Ho;Lee, Sung-Jin;Kim, Byung-Min
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.8
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    • pp.855-861
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    • 2011
  • We predict the rolled-strip profile for a 6-high mill using thin rolling theory and a numerical model. In the numerical model, we calculate the distributions of the contact pressures between the rolls and the rolling pressure between the strip and the work roll in the transverse direction using the geometric structure of the 6-high mill and the boundary conditions. We determine the distribution of the rolling pressure in the rolling direction via a thin-foil rolling model using Fleck's theory. We calculate the three-dimensional elastic deformation of the work roll using the pressures of the width and rolling directions. We then obtain the three-dimensional strip profile via the elastic deformation of the work roll during the rolling process. The profile is verified by a thin cold-rolling test and FE simulation.

Improvement of shear deformation by controlling reduction per a rolling pass during asymmetrical cold rolling in AA 5052 (AA5052 판재의 비대칭 냉간압연 시 압연 패스당 압하율 제어에 의한 전단 변형 향상)

  • Kang, H.G.;Han, Y.H.;Huh, M.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.226-228
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    • 2007
  • During asymmetrical cold rolling in AA 5052 sheet a reduction per a rolling pass was varied to investigate the effect of the ratio of the contact length between the roll and sample ($l_c$) to the sheet thickness (d) on the formation of shear textures. In order to intensify the shear deformation during asymmetrical rolling, AA 5052 sheet was asymmetrically cold rolled without lubrication by using different roll velocities of upper and lower rolls. Asymmetrical rolling with $l_c$/d=1.8 led to the formation of texture gradients throughout the sheet thickness in which the outer thickness layers depicted shear textures and the center thickness layers displayed a rolling texture. Asymmetrical rolling with $l_c$/d=3.1 gave rise to the formation of shear textures in the whole through-thickness layer. The strain states associated with asymmetrical rolling were investigated by the finite element method (FEM) simulation. FEM results indicated that the evolution of deformation texture in a thickness layer is strongly governed by integrated values of strain rates and along the streamline in the roll gap.

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Collision-induced Derailment Analysis of a Finite Element Model of Rolling Stock Applying Rolling Contacts for Wheel-rail Interaction (차륜-레일 구름접촉을 적용한 철도차량 유한요소 모델의 충돌 기인 탈선거동 해석)

  • Lee, Junho;Koo, Jeongseo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.3
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    • pp.1-14
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    • 2013
  • In this paper, a finite element analysis technique of rolling stock models for collision-induced derailments was suggested using rolling contacts for wheel-rail interaction. The collision-induced derailments of rolling stock can be categorized into two patterns of wheel-climb and wheel-lift according to the friction direction between wheel flange and rail. The wheel-climb derailment types are classified as Climb-up, Climb/roll-over and Roll-over-C types, and the wheel-lift derailment types as Slip-up, Slip/roll-over and Roll-over-L types. To verify the rolling contact simulations for wheel-rail interaction, dynamic simulations of a single wheelset using Recurdyn of Functionbay and Ls-Dyna of LSTC were performed and compared for the 6-typical derailments. The collision-induced derailment simulation of the finite element model of KHST (Korean High Speed Train) was conducted and verified using the theoretical predictions of a simplified wheel-set model proposed for each derailment type.

Modeling and Simulation of a Ship with Anti-Rolling Devices in Waves (자세제어장비를 장착한 선박의 파랑중 운동 모델링 및 시뮬레이션)

  • 윤현규;이경중;이창민
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2004.04a
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    • pp.285-290
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    • 2004
  • Wave exciting force and moment generate the motions of a ship in waves. Since ship motion exerts the negative influences on a crew's operability, the safety of cargos, passenger's comfort, etc, the anti-rolling devices may be required to reduce such motion. In this paper, the dynamics of the anti-rolling devices such as passive and active moving weight stabilizer and anti-rolling tank, and fin stabilizer are mathematically modeled. While the effect of the motion of the anti-rolling device on a ship was taken into consideration in roll mode only in the past, the 6 DOF coupled equations of motion between a ship and the anti-rolling devices are constituted. Finally the motion of a ship with anti-rolling devices in waves is simulated through the developed simulation program.

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Improvement of Rolling Load Prediction with Consideration of Spread in Hot Rolling (푹 퍼짐을 고려한 열연공정 압연하중 설정정확도 개선)

  • Jeong, Jong-Yeop;Im, Yong-Taek
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.11
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    • pp.2836-2844
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    • 2000
  • Thickness control of hot-rolled strips has become an important issue in recent years because of the need for improving the quality of the hot-rolled strip. In this study, a modifying method of rolling force set-up with consideration of spread was developed to improve the thickness uniformity at the finishing rolling units in hot rolling. Through the analysis of real production data it was found that the accuracy of the rolling force determined from the finishing mill set-up (FSU) model dominantly governed the thickness uniformity in rolled plates at the front. Based on this analysis , several examples were selected to calculate the spread of rolled plate using three dimensional rigid thermo-viscoplastic finite element program. FE analysis results were used to train the neural network system that can predict the spread hot-rolled plate and the rolling force was modified based on the predicted value of spread. The modified rolling forces were closer to the measured rolling force so it can be expected that the accuracy of thickness uniformity of hot-rolled plate will be improved.

A Revamping of Pickling and Tandem Cold Rolling Mill for Producing Stainless Steel (Stainless 생산을 위한 냉연 합리화)

  • Lee D. H.;Ki E. D.;Cho S. B.;Lee K. B.;Kim D. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2004.08a
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    • pp.109-118
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    • 2004
  • No.2 PCM (Pickling and tandem cold rolling mill) at Pohang works was revamped in 2003. The purpose of this project is to produce carbon and stainless steel using conventional carbon production process, rolling and annealing. This paper introduces the applied facilities and technologies of PCM which are used in production of carbon and stainless steel. To realize the main purpose of this project, POSCO have developed laser weld technology in normal carbon and special steel (stainless, high carbon and high silicon). And this report describes the method which is developed to get down the surface defect of stainless 400 series. After revamping, No.2 PCM can have competitive power in this field and can supply the special steel using carbon rolling process.

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