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Effect of flow stress characteristic and process condition on width spread in horizontal hot rolling

NGUYEN, Thi Nhan (Pohang University of Science and Technology)

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In horizontal rolling, the need for evaluating the effect of flow stress characteristic and process condition on width spread is necessary to control precision of width spread after rolling. With the right evaluation, we can know the significant factors that cause error between simulation results an...
In horizontal rolling, the need for evaluating the effect of flow stress characteristic and process condition on width spread is necessary to control precision of width spread after rolling. With the right evaluation, we can know the significant factors that cause error between simulation results and experiment data. Hence, proper adjustment in input data will be perform to get better result. The effect of flow stress based on different material properties and process condition includes rolling velocity, friction between roller and strip and rolling temperature. With sets of simulations using Finite Element Method (FEM), we investigate the effect of each factor and determine the behavior of width spread after rolling with the changing of material and process condition. From the result of FEM simulation, the effect of rolling velocity and rolling temperature on width spread could be neglected. Friction has a slight influence on width spread. A series of simulations was conducted using different type of stress models such as constant model, Shida model, Minami model and general form of flow stress to investigate the effect of flow stress magnitude and its characteristic, which includes strain hardening and strain rate hardening, on width spread. The result showed clearly that the magnitude of width spread would not affect the width spread. Otherwise, the width spread is really sensitive to the change of flow stress characteristic.
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ABSTRACT I
CONTENTS II
LIST OF TABLES IV
...
ABSTRACT I
CONTENTS II
LIST OF TABLES IV
LIST OF FIGURES V
NOMENICLATURE VII
1 INTRODUCTION 1
2 FUNDAMENTALS AND THEORIES 2
2.1 Theory of width change 2
2.2 Conventional model for the prediction of width spread in flat rolling 5
2.2.1 Hill and McCrum formula 5
2.2.2 Wusatowski formula 5
2.2.3 El-kalay and Sparling formula 5
2.2.4 Helmi and Alexander formula 6
2.2.5 Beese formular 6
2.2.6 Shibahara, et al formula 7
2.2.7 D.H. Lee, et al. formula 7
2.3 Effect of process condition and flow stress on width spread 9
2.3.1 Effect of coefficient of friction 9
2.3.2 Effect of velocity 10
2.3.3 Effect of temperature 11
2.3.4 Effect of Carbon content 12
2.4 Flow stress models 16
2.4.1 Constant flow stress 16
2.4.2 Shida flow stress 16
2.4.3 Misaka flow stress 17
2.4.4 Minami et al. flow stress 18
2.4.5 General double-power constitutive equation 18
3 FINITE ELEMENT METHOD SIMULATIONS 21
3.1 Simulation setup 21
3.1.1 Strip and roll profile 21
3.1.2 Process condition 22
3.1.3 Flow stress models 22
3.2 Simulation results and discussion 30
3.2.1 Effect of friction on width spread 30
3.2.2 Effect of rolling velocity on width spread 30
3.2.3 Effect of temperature on width spread 30
3.2.4 Effect of Carbon content 37
3.2.5 Effect of flow stress magnitude 41
3.2.6 Effect of flow stress characteristic 41
4 CONCLUDING REMARKS 51
SUMMARY 53
REFERENCES 55
Acknowledgements 1