Avrami Kinetic-Based Constitutive Relationship for Armco-Type Pure Iron in Hot Deformation

The work presents a full mathematical description of the stress-strain compression curves in a wide range of strain rates and deformation temperatures for Armco-type pure iron. The constructed models are based on a dislocation structure evolution equation (in the case of dynamic recovery (DRV)) and...

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Main Authors: Yan Zhang, Qichao Fan, Xiaofeng Zhang, Zhaohui Zhou, Zhihui Xia, Zhiqiang Qian
Format: Article
Language:English
Published: MDPI AG 2019-03-01
Series:Metals
Subjects:
Online Access:https://www.mdpi.com/2075-4701/9/3/365
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author Yan Zhang
Qichao Fan
Xiaofeng Zhang
Zhaohui Zhou
Zhihui Xia
Zhiqiang Qian
author_facet Yan Zhang
Qichao Fan
Xiaofeng Zhang
Zhaohui Zhou
Zhihui Xia
Zhiqiang Qian
author_sort Yan Zhang
collection DOAJ
description The work presents a full mathematical description of the stress-strain compression curves in a wide range of strain rates and deformation temperatures for Armco-type pure iron. The constructed models are based on a dislocation structure evolution equation (in the case of dynamic recovery (DRV)) and Avrami kinetic-based model (in the case of dynamic recrystallization (DRX)). The fractional softening model is modified as: <inline-formula> <math display="inline"> <semantics> <mrow> <mi>X</mi> <mo>=</mo> <mo stretchy="false">(</mo> <msup> <mi>&#963;</mi> <mn>2</mn> </msup> <mo>&#8722;</mo> <msubsup> <mi>&#963;</mi> <mi>r</mi> <mn>2</mn> </msubsup> <mo stretchy="false">)</mo> <mo>/</mo> <mo stretchy="false">(</mo> <msubsup> <mi>&#963;</mi> <mrow> <mi>d</mi> <mi>s</mi> </mrow> <mn>2</mn> </msubsup> <mo>&#8722;</mo> <msubsup> <mi>&#963;</mi> <mi>r</mi> <mn>2</mn> </msubsup> <mo stretchy="false">)</mo> </mrow> </semantics> </math> </inline-formula> considering the strain hardening of un-recrystallized regions. The Avrami kinetic equation is modified and used to describe the DRX process considering the strain rate and temperature. The relations between the Avrami constant <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mi>k</mi> <mo>&#8727;</mo> </msup> </mrow> </semantics> </math> </inline-formula>, time exponent <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mi>n</mi> <mo>&#8727;</mo> </msup> </mrow> </semantics> </math> </inline-formula>, strain rate <inline-formula> <math display="inline"> <semantics> <mover accent="true"> <mi>&#949;</mi> <mo>˙</mo> </mover> </semantics> </math> </inline-formula>, temperature <inline-formula> <math display="inline"> <semantics> <mi>T</mi> </semantics> </math> </inline-formula> and <inline-formula> <math display="inline"> <semantics> <mi>Z</mi> </semantics> </math> </inline-formula> parameter are discussed. The yield stress <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mi>&#963;</mi> <mi>y</mi> </msub> </mrow> </semantics> </math> </inline-formula>, saturation stress <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mi>&#963;</mi> <mrow> <mi>r</mi> <mi>s</mi> </mrow> </msub> </mrow> </semantics> </math> </inline-formula>, steady stress <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mi>&#963;</mi> <mrow> <mi>d</mi> <mi>s</mi> </mrow> </msub> </mrow> </semantics> </math> </inline-formula> and critical strain <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mi>&#949;</mi> <mi>c</mi> </msub> </mrow> </semantics> </math> </inline-formula> are expressed as the functions of the <inline-formula> <math display="inline"> <semantics> <mi>Z</mi> </semantics> </math> </inline-formula> parameter. A constitutive model is constructed based on the strain-hardening model, fractional softening model and modified Avrami kinetic equation. The DRV and DRX characters of Armco-type pure iron are clearly presented in these flow stress curves determined by the model.
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spelling doaj.art-01892f96f9ce45aca9de251bf6c84c842022-12-22T03:32:38ZengMDPI AGMetals2075-47012019-03-019336510.3390/met9030365met9030365Avrami Kinetic-Based Constitutive Relationship for Armco-Type Pure Iron in Hot DeformationYan Zhang0Qichao Fan1Xiaofeng Zhang2Zhaohui Zhou3Zhihui Xia4Zhiqiang Qian5Institute of Machinery Manufacturing Technology, Chinese Academy of Engineering Physics, Mianyang 621900, ChinaInstitute of Machinery Manufacturing Technology, Chinese Academy of Engineering Physics, Mianyang 621900, ChinaInstitute of Machinery Manufacturing Technology, Chinese Academy of Engineering Physics, Mianyang 621900, ChinaInstitute of Machinery Manufacturing Technology, Chinese Academy of Engineering Physics, Mianyang 621900, ChinaInstitute of Machinery Manufacturing Technology, Chinese Academy of Engineering Physics, Mianyang 621900, ChinaInstitute of Machinery Manufacturing Technology, Chinese Academy of Engineering Physics, Mianyang 621900, ChinaThe work presents a full mathematical description of the stress-strain compression curves in a wide range of strain rates and deformation temperatures for Armco-type pure iron. The constructed models are based on a dislocation structure evolution equation (in the case of dynamic recovery (DRV)) and Avrami kinetic-based model (in the case of dynamic recrystallization (DRX)). The fractional softening model is modified as: <inline-formula> <math display="inline"> <semantics> <mrow> <mi>X</mi> <mo>=</mo> <mo stretchy="false">(</mo> <msup> <mi>&#963;</mi> <mn>2</mn> </msup> <mo>&#8722;</mo> <msubsup> <mi>&#963;</mi> <mi>r</mi> <mn>2</mn> </msubsup> <mo stretchy="false">)</mo> <mo>/</mo> <mo stretchy="false">(</mo> <msubsup> <mi>&#963;</mi> <mrow> <mi>d</mi> <mi>s</mi> </mrow> <mn>2</mn> </msubsup> <mo>&#8722;</mo> <msubsup> <mi>&#963;</mi> <mi>r</mi> <mn>2</mn> </msubsup> <mo stretchy="false">)</mo> </mrow> </semantics> </math> </inline-formula> considering the strain hardening of un-recrystallized regions. The Avrami kinetic equation is modified and used to describe the DRX process considering the strain rate and temperature. The relations between the Avrami constant <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mi>k</mi> <mo>&#8727;</mo> </msup> </mrow> </semantics> </math> </inline-formula>, time exponent <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mi>n</mi> <mo>&#8727;</mo> </msup> </mrow> </semantics> </math> </inline-formula>, strain rate <inline-formula> <math display="inline"> <semantics> <mover accent="true"> <mi>&#949;</mi> <mo>˙</mo> </mover> </semantics> </math> </inline-formula>, temperature <inline-formula> <math display="inline"> <semantics> <mi>T</mi> </semantics> </math> </inline-formula> and <inline-formula> <math display="inline"> <semantics> <mi>Z</mi> </semantics> </math> </inline-formula> parameter are discussed. The yield stress <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mi>&#963;</mi> <mi>y</mi> </msub> </mrow> </semantics> </math> </inline-formula>, saturation stress <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mi>&#963;</mi> <mrow> <mi>r</mi> <mi>s</mi> </mrow> </msub> </mrow> </semantics> </math> </inline-formula>, steady stress <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mi>&#963;</mi> <mrow> <mi>d</mi> <mi>s</mi> </mrow> </msub> </mrow> </semantics> </math> </inline-formula> and critical strain <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mi>&#949;</mi> <mi>c</mi> </msub> </mrow> </semantics> </math> </inline-formula> are expressed as the functions of the <inline-formula> <math display="inline"> <semantics> <mi>Z</mi> </semantics> </math> </inline-formula> parameter. A constitutive model is constructed based on the strain-hardening model, fractional softening model and modified Avrami kinetic equation. The DRV and DRX characters of Armco-type pure iron are clearly presented in these flow stress curves determined by the model.https://www.mdpi.com/2075-4701/9/3/365Avrami kineticconstitutive modeldynamic recoverydynamic recrystallizationhot deformationpure iron
spellingShingle Yan Zhang
Qichao Fan
Xiaofeng Zhang
Zhaohui Zhou
Zhihui Xia
Zhiqiang Qian
Avrami Kinetic-Based Constitutive Relationship for Armco-Type Pure Iron in Hot Deformation
Metals
Avrami kinetic
constitutive model
dynamic recovery
dynamic recrystallization
hot deformation
pure iron
title Avrami Kinetic-Based Constitutive Relationship for Armco-Type Pure Iron in Hot Deformation
title_full Avrami Kinetic-Based Constitutive Relationship for Armco-Type Pure Iron in Hot Deformation
title_fullStr Avrami Kinetic-Based Constitutive Relationship for Armco-Type Pure Iron in Hot Deformation
title_full_unstemmed Avrami Kinetic-Based Constitutive Relationship for Armco-Type Pure Iron in Hot Deformation
title_short Avrami Kinetic-Based Constitutive Relationship for Armco-Type Pure Iron in Hot Deformation
title_sort avrami kinetic based constitutive relationship for armco type pure iron in hot deformation
topic Avrami kinetic
constitutive model
dynamic recovery
dynamic recrystallization
hot deformation
pure iron
url https://www.mdpi.com/2075-4701/9/3/365
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AT xiaofengzhang avramikineticbasedconstitutiverelationshipforarmcotypepureironinhotdeformation
AT zhaohuizhou avramikineticbasedconstitutiverelationshipforarmcotypepureironinhotdeformation
AT zhihuixia avramikineticbasedconstitutiverelationshipforarmcotypepureironinhotdeformation
AT zhiqiangqian avramikineticbasedconstitutiverelationshipforarmcotypepureironinhotdeformation