Cavity growth in a superplastic Al-Mg alloy

II. An improved plasticity based model

DongHyun Bae, A. K. Ghosh

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

The extent of cavity growth estimated from a combination of diffusional and plasticity based growth models generally underestimates the actual cavity growth in superplastic alloys. It has been shown that in a fine grain Al-Mg alloy, cavity growth begins by matrix/particle debonding at grain boundary particles (Mat. Sci. Forum, Trans. Tech. Pub. 304-306 (1999) 609), and also from pre-existing voids. In this study, cavity growth beyond interface decohesion is modeled in which deformation of the matrix surrounding the cavity is free from interface constraint, but it still experiences an accelerated local deformation rate. Stress and strain-rate in this region are intensified due to the perturbed flow field near the cavity, and not relaxed during the time frame for superplastic forming. This local deformation around the cavity is a function of strain-rate sensitivity, m, the level of strain concentration, and the cavity spacing. Two important effects not previously considered: (i) local stress concentration around the cavities, and (ii) continuous nucleation of new cavities, have been included in this work. Using this model that is suitable for low overall cavity volume (i.e. no cavity coalescence), faster growth rate is predicted for single cavities when strain-rate sensitivity is low and/or the population density of cavities is low (generally at slow strain-rates). By combining the predicted growth rate of individual cavities with the emerging cavity population density determined experimentally, a quantitative understanding of the various complex dependencies of cavitation has been obtained.

Original languageEnglish
Pages (from-to)1011-1029
Number of pages19
JournalActa Materialia
Volume50
Issue number5
DOIs
Publication statusPublished - 2002 Mar 14

Fingerprint

Plasticity
Strain rate
Debonding
Coalescence
Cavitation
Stress concentration
Flow fields
Grain boundaries
Nucleation

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

Cite this

@article{a822d9d9a39b43f294338e8ff7894708,
title = "Cavity growth in a superplastic Al-Mg alloy: II. An improved plasticity based model",
abstract = "The extent of cavity growth estimated from a combination of diffusional and plasticity based growth models generally underestimates the actual cavity growth in superplastic alloys. It has been shown that in a fine grain Al-Mg alloy, cavity growth begins by matrix/particle debonding at grain boundary particles (Mat. Sci. Forum, Trans. Tech. Pub. 304-306 (1999) 609), and also from pre-existing voids. In this study, cavity growth beyond interface decohesion is modeled in which deformation of the matrix surrounding the cavity is free from interface constraint, but it still experiences an accelerated local deformation rate. Stress and strain-rate in this region are intensified due to the perturbed flow field near the cavity, and not relaxed during the time frame for superplastic forming. This local deformation around the cavity is a function of strain-rate sensitivity, m, the level of strain concentration, and the cavity spacing. Two important effects not previously considered: (i) local stress concentration around the cavities, and (ii) continuous nucleation of new cavities, have been included in this work. Using this model that is suitable for low overall cavity volume (i.e. no cavity coalescence), faster growth rate is predicted for single cavities when strain-rate sensitivity is low and/or the population density of cavities is low (generally at slow strain-rates). By combining the predicted growth rate of individual cavities with the emerging cavity population density determined experimentally, a quantitative understanding of the various complex dependencies of cavitation has been obtained.",
author = "DongHyun Bae and Ghosh, {A. K.}",
year = "2002",
month = "3",
day = "14",
doi = "10.1016/S1359-6454(01)00400-1",
language = "English",
volume = "50",
pages = "1011--1029",
journal = "Acta Materialia",
issn = "1359-6454",
publisher = "Elsevier Limited",
number = "5",

}

Cavity growth in a superplastic Al-Mg alloy : II. An improved plasticity based model. / Bae, DongHyun; Ghosh, A. K.

In: Acta Materialia, Vol. 50, No. 5, 14.03.2002, p. 1011-1029.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Cavity growth in a superplastic Al-Mg alloy

T2 - II. An improved plasticity based model

AU - Bae, DongHyun

AU - Ghosh, A. K.

PY - 2002/3/14

Y1 - 2002/3/14

N2 - The extent of cavity growth estimated from a combination of diffusional and plasticity based growth models generally underestimates the actual cavity growth in superplastic alloys. It has been shown that in a fine grain Al-Mg alloy, cavity growth begins by matrix/particle debonding at grain boundary particles (Mat. Sci. Forum, Trans. Tech. Pub. 304-306 (1999) 609), and also from pre-existing voids. In this study, cavity growth beyond interface decohesion is modeled in which deformation of the matrix surrounding the cavity is free from interface constraint, but it still experiences an accelerated local deformation rate. Stress and strain-rate in this region are intensified due to the perturbed flow field near the cavity, and not relaxed during the time frame for superplastic forming. This local deformation around the cavity is a function of strain-rate sensitivity, m, the level of strain concentration, and the cavity spacing. Two important effects not previously considered: (i) local stress concentration around the cavities, and (ii) continuous nucleation of new cavities, have been included in this work. Using this model that is suitable for low overall cavity volume (i.e. no cavity coalescence), faster growth rate is predicted for single cavities when strain-rate sensitivity is low and/or the population density of cavities is low (generally at slow strain-rates). By combining the predicted growth rate of individual cavities with the emerging cavity population density determined experimentally, a quantitative understanding of the various complex dependencies of cavitation has been obtained.

AB - The extent of cavity growth estimated from a combination of diffusional and plasticity based growth models generally underestimates the actual cavity growth in superplastic alloys. It has been shown that in a fine grain Al-Mg alloy, cavity growth begins by matrix/particle debonding at grain boundary particles (Mat. Sci. Forum, Trans. Tech. Pub. 304-306 (1999) 609), and also from pre-existing voids. In this study, cavity growth beyond interface decohesion is modeled in which deformation of the matrix surrounding the cavity is free from interface constraint, but it still experiences an accelerated local deformation rate. Stress and strain-rate in this region are intensified due to the perturbed flow field near the cavity, and not relaxed during the time frame for superplastic forming. This local deformation around the cavity is a function of strain-rate sensitivity, m, the level of strain concentration, and the cavity spacing. Two important effects not previously considered: (i) local stress concentration around the cavities, and (ii) continuous nucleation of new cavities, have been included in this work. Using this model that is suitable for low overall cavity volume (i.e. no cavity coalescence), faster growth rate is predicted for single cavities when strain-rate sensitivity is low and/or the population density of cavities is low (generally at slow strain-rates). By combining the predicted growth rate of individual cavities with the emerging cavity population density determined experimentally, a quantitative understanding of the various complex dependencies of cavitation has been obtained.

UR - http://www.scopus.com/inward/record.url?scp=0037075769&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0037075769&partnerID=8YFLogxK

U2 - 10.1016/S1359-6454(01)00400-1

DO - 10.1016/S1359-6454(01)00400-1

M3 - Article

VL - 50

SP - 1011

EP - 1029

JO - Acta Materialia

JF - Acta Materialia

SN - 1359-6454

IS - 5

ER -