The origin of fracture in the I-ECAP of AZ31B magnesium alloy

Michal Gzyl, Andrzej Rosochowski, Sonia Boczkal, Muhammad Jawad Qarni

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Magnesium alloys are very promising materials for weight-saving structural applications due to their low density, comparing to other metals and alloys currently used. However, they usually suffer from a limited formability at room temperature and low strength. In order to overcome those issues, processes of severe plastic deformation (SPD) can be utilized to improve mechanical properties, but processing parameters need to be selected with care to avoid fracture, very often observed for those alloys during forming. In the current work, the AZ31B magnesium alloy was subjected to SPD by incremental equal-channel angular pressing (I-ECAP) at temperatures varying from 398 K to 525 K (125 °C to 250 °C) to determine the window of allowable processing parameters. The effects of initial grain size and billet rotation scheme on the occurrence of fracture during I-ECAP were investigated. The initial grain size ranged from 1.5 to 40 µm and the I-ECAP routes tested were A, BC, and C. Microstructures of the processed billets were characterized before and after I-ECAP. It was found that a fine-grained and homogenous microstructure was required to avoid fracture at low temperatures. Strain localization arising from a stress relaxation within recrystallized regions, namely twins and fine-grained zones, was shown to be responsible for the generation of microcracks. Based on the I-ECAP experiments and available literature data for ECAP, a power law between the initial grain size and processing conditions, described by a Zener–Hollomon parameter, has been proposed. Finally, processing by various routes at 473 K (200 °C) revealed that route A was less prone to fracture than routes BC and C.

LanguageEnglish
Pages5275-5284
Number of pages10
JournalMetallurgical and Materials Transactions A
Volume46
Issue number11
Early online date29 Jul 2015
DOIs
Publication statusPublished - Nov 2015

Fingerprint

Equal channel angular pressing
magnesium alloys
pressing
Magnesium alloys
routes
billets
grain size
Processing
plastic deformation
Plastic deformation
structural weight
microstructure
Microstructure
microcracks
stress relaxation
Microcracks
Stress relaxation
Formability
Temperature
Metals

Keywords

  • structural materials
  • metallic materials
  • magnesium alloys
  • severe plastic deformation (SPD)

Cite this

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abstract = "Magnesium alloys are very promising materials for weight-saving structural applications due to their low density, comparing to other metals and alloys currently used. However, they usually suffer from a limited formability at room temperature and low strength. In order to overcome those issues, processes of severe plastic deformation (SPD) can be utilized to improve mechanical properties, but processing parameters need to be selected with care to avoid fracture, very often observed for those alloys during forming. In the current work, the AZ31B magnesium alloy was subjected to SPD by incremental equal-channel angular pressing (I-ECAP) at temperatures varying from 398 K to 525 K (125 °C to 250 °C) to determine the window of allowable processing parameters. The effects of initial grain size and billet rotation scheme on the occurrence of fracture during I-ECAP were investigated. The initial grain size ranged from 1.5 to 40 µm and the I-ECAP routes tested were A, BC, and C. Microstructures of the processed billets were characterized before and after I-ECAP. It was found that a fine-grained and homogenous microstructure was required to avoid fracture at low temperatures. Strain localization arising from a stress relaxation within recrystallized regions, namely twins and fine-grained zones, was shown to be responsible for the generation of microcracks. Based on the I-ECAP experiments and available literature data for ECAP, a power law between the initial grain size and processing conditions, described by a Zener–Hollomon parameter, has been proposed. Finally, processing by various routes at 473 K (200 °C) revealed that route A was less prone to fracture than routes BC and C.",
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The origin of fracture in the I-ECAP of AZ31B magnesium alloy. / Gzyl, Michal; Rosochowski, Andrzej; Boczkal, Sonia; Qarni, Muhammad Jawad.

In: Metallurgical and Materials Transactions A, Vol. 46, No. 11, 11.2015, p. 5275-5284.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The origin of fracture in the I-ECAP of AZ31B magnesium alloy

AU - Gzyl, Michal

AU - Rosochowski, Andrzej

AU - Boczkal, Sonia

AU - Qarni, Muhammad Jawad

PY - 2015/11

Y1 - 2015/11

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T2 - Metallurgical and Materials Transactions A

JF - Metallurgical and Materials Transactions A

SN - 1073-5623

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