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An experimental study of hot rolling with low finishing temperature of an extra-low carbon steel.

Record Type:	Electronic resources : Monograph/item
Title/Author:	An experimental study of hot rolling with low finishing temperature of an extra-low carbon steel./
Author:	Hwu, Yhu-Jen.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 1995,
Description:	287 p.
Notes:	Source: Dissertations Abstracts International, Volume: 76-02, Section: B.
Contained By:	Dissertations Abstracts International76-02B.
Subject:	Mechanical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NN03581
ISBN:	9780612035812

An experimental study of hot rolling with low finishing temperature of an extra-low carbon steel.
Hwu, Yhu-Jen.

An experimental study of hot rolling with low finishing temperature of an extra-low carbon steel. - Ann Arbor : ProQuest Dissertations & Theses, 1995 - 287 p.

Source: Dissertations Abstracts International, Volume: 76-02, Section: B.

Thesis (Ph.D.)--University of Waterloo (Canada), 1995.

This item must not be sold to any third party vendors.

For the purpose of improving the physical and mechanical properties of extra-low carbon electrical steels, rolling at low finishing temperatures is unavoidable. In order to overcome the attendant problems in gauge control, which are ascribed to the difficulty in accurate prediction of the flow stress in the two-phase region, two critical phenomena should be considered: (1) Under what circumstances will the phase transformation from $\\gamma$ to $\\alpha$ take place? and (2) How can the flow stress and the roll force in the two-phase region be predicted accurately? To answer the first equation, the effects of initial grain size, cooling rate, deformation conditions and static recrystallization on the phase transformation temperature are investigated. It is shown that only two variables, residual strain and cooling rate, dominate the phase transformation temperature. When the residual strain is below a critical value, the Ar$\\sb3$ and Ar$\\sb1$ increase with the increase of residual strain. When the residual strain is beyond that critical value, the Ar$\\sb3$ and Ar$\\sb1$ remain steady. The steady temperature of Ar$\\sb3$ is independent of cooling rate within a range from 4.5$\\sp\\circ$C/s to 40$\\sp\\circ$C/s. However, the steady temperature Ar$\\sb1$ decreases as the cooling rate increases. Based on the assumption that the cooling rate varies linearly from the starting to the finishing point during phase transformation, thermal analysis of cooling curves is carried out and a variable X$\\sb{\\rm q}$, called the quasi-volume fraction, is developed. The flow stresses in the two-phase region are measured under continuous cooling conditions. It is found that the softening ratio of the flow stress, due to phase transformation, can be expressed as a quadratic equation of X$\\sb{\\rm q}$. Based on this relation, the flow stresses in the two-phase region can be predicted accurately. The average flow stresses in the austenite and ferrite region are measured and modelled successfully by a neural network, called the flow network. The average flow temperatures in the roll bite under different conditions are calculated by a finite element program and the database is handled by a neural network, called the temperature network. The adapted geometric multipliers, Q$\\sb{\\rm p}$, in Alexander's model are calculated based on the model and the measured roll forces in the austenite and ferrite regions. These adapted Q$\\sb{\\rm p}$'s are also modelled by a neural network, called the adaptive network. A method, combining those three neural works, flow stress network, temperature network and adaptive network, with Alexander's model is developed to calculate roll force. This model can learn by itself and has a short computing time. Using single-pass and three-pass rolling data, it is shown that this method can predict roll forces in the austenite, two-phase and ferrite regions accurately.

ISBN: 9780612035812Subjects--Topical Terms:

649730
Mechanical engineering.

An experimental study of hot rolling with low finishing temperature of an extra-low carbon steel.
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008 241004s1995 ||||||||||||||||| ||eng d
020 $a 9780612035812
035 $a (MiAaPQ)AAINN03581
035 $a AAINN03581
040 $a MiAaPQ $c MiAaPQ
100 1 $a Hwu, Yhu-Jen. $3 3688787
245 1 3 $a An experimental study of hot rolling with low finishing temperature of an extra-low carbon steel.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 1995
300 $a 287 p.
500 $a Source: Dissertations Abstracts International, Volume: 76-02, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Lenard, J. G.
502 $a Thesis (Ph.D.)--University of Waterloo (Canada), 1995.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a For the purpose of improving the physical and mechanical properties of extra-low carbon electrical steels, rolling at low finishing temperatures is unavoidable. In order to overcome the attendant problems in gauge control, which are ascribed to the difficulty in accurate prediction of the flow stress in the two-phase region, two critical phenomena should be considered: (1) Under what circumstances will the phase transformation from $\\gamma$ to $\\alpha$ take place? and (2) How can the flow stress and the roll force in the two-phase region be predicted accurately? To answer the first equation, the effects of initial grain size, cooling rate, deformation conditions and static recrystallization on the phase transformation temperature are investigated. It is shown that only two variables, residual strain and cooling rate, dominate the phase transformation temperature. When the residual strain is below a critical value, the Ar$\\sb3$ and Ar$\\sb1$ increase with the increase of residual strain. When the residual strain is beyond that critical value, the Ar$\\sb3$ and Ar$\\sb1$ remain steady. The steady temperature of Ar$\\sb3$ is independent of cooling rate within a range from 4.5$\\sp\\circ$C/s to 40$\\sp\\circ$C/s. However, the steady temperature Ar$\\sb1$ decreases as the cooling rate increases. Based on the assumption that the cooling rate varies linearly from the starting to the finishing point during phase transformation, thermal analysis of cooling curves is carried out and a variable X$\\sb{\\rm q}$, called the quasi-volume fraction, is developed. The flow stresses in the two-phase region are measured under continuous cooling conditions. It is found that the softening ratio of the flow stress, due to phase transformation, can be expressed as a quadratic equation of X$\\sb{\\rm q}$. Based on this relation, the flow stresses in the two-phase region can be predicted accurately. The average flow stresses in the austenite and ferrite region are measured and modelled successfully by a neural network, called the flow network. The average flow temperatures in the roll bite under different conditions are calculated by a finite element program and the database is handled by a neural network, called the temperature network. The adapted geometric multipliers, Q$\\sb{\\rm p}$, in Alexander's model are calculated based on the model and the measured roll forces in the austenite and ferrite regions. These adapted Q$\\sb{\\rm p}$'s are also modelled by a neural network, called the adaptive network. A method, combining those three neural works, flow stress network, temperature network and adaptive network, with Alexander's model is developed to calculate roll force. This model can learn by itself and has a short computing time. Using single-pass and three-pass rolling data, it is shown that this method can predict roll forces in the austenite, two-phase and ferrite regions accurately.
590 $a School code: 1141.
650 4 $a Mechanical engineering. $3 649730
650 4 $a Metallurgy. $3 535414
690 $a 0548
690 $a 0794
710 2 $a University of Waterloo (Canada). $3 1017669
773 0 $t Dissertations Abstracts International $g 76-02B.
790 $a 1141
791 $a Ph.D.
792 $a 1995
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NN03581