Microstructural evolution and its effect on Hall-Petch relationship in friction stir welding of thixomolded Mg alloy AZ91D

Seung Hwan C. Park; Yutaka S. Sato; Hiroyuki Kokawa

doi:10.1023/A:1026351619636

Microstructural evolution and its effect on Hall-Petch relationship in friction stir welding of thixomolded Mg alloy AZ91D

Seung Hwan C. Park, Yutaka S. Sato, Hiroyuki Kokawa

ENG - Materials Processing

Tohoku University

Research output: Contribution to journal › Article › peer-review

148 Citations (Scopus)

Abstract

Microstructural evolution of a thixomolded magnesium (Mg) alloy AZ91D during friction stir welding was investigated. Friction stir welding resulted in a homogeneous microstructure consisting of fine recrystallised α-Mg grains in the thixomolded material. The microstructural homogenisation and refinement was attributed to dynamic recrystallisation accompanied by the dissolution of the eutectic structure during the welding. The grain refinement in the stir zone was effective in increasing the hardness, as predicted by the Hall-Petch equation. The effect of grain size on hardness was smaller than that in conventional and rapidly solidified AZ91. This phenomenon may be explained as being due to the microstructure of the stir zone which consisted of fine equiaxed grains with a high density of dislocations.

Original language	English
Pages (from-to)	4379-4383
Number of pages	5
Journal	Journal of Materials Science
Volume	38
Issue number	21
DOIs	https://doi.org/10.1023/A:1026351619636
Publication status	Published - 2003 Nov 1

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title = "Microstructural evolution and its effect on Hall-Petch relationship in friction stir welding of thixomolded Mg alloy AZ91D",

abstract = "Microstructural evolution of a thixomolded magnesium (Mg) alloy AZ91D during friction stir welding was investigated. Friction stir welding resulted in a homogeneous microstructure consisting of fine recrystallised α-Mg grains in the thixomolded material. The microstructural homogenisation and refinement was attributed to dynamic recrystallisation accompanied by the dissolution of the eutectic structure during the welding. The grain refinement in the stir zone was effective in increasing the hardness, as predicted by the Hall-Petch equation. The effect of grain size on hardness was smaller than that in conventional and rapidly solidified AZ91. This phenomenon may be explained as being due to the microstructure of the stir zone which consisted of fine equiaxed grains with a high density of dislocations.",

author = "Park, {Seung Hwan C.} and Sato, {Yutaka S.} and Hiroyuki Kokawa",

note = "Funding Information: The authors are grateful to Mr. A. Honda for technical assistance and thank Prof. K. Ikeda, Prof.K. Maruyama, Prof. Z. J. Wang, Prof. J. Koike, Dr. M. Suzuki, Prof. H. Sato and Dr. T. Tsukeda for their helpful discussions. Financial support from the Japan Ministry of Education, Culture, Sports, Science and Technology for the Promotion of Science with a Grant-in-Aid for Young Researchers and for 21st century COE program in International Center of Research and Education for Materials at Tohoku University is gratefully acknowledged.",

year = "2003",

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doi = "10.1023/A:1026351619636",

language = "English",

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T1 - Microstructural evolution and its effect on Hall-Petch relationship in friction stir welding of thixomolded Mg alloy AZ91D

AU - Park, Seung Hwan C.

AU - Sato, Yutaka S.

AU - Kokawa, Hiroyuki

N1 - Funding Information: The authors are grateful to Mr. A. Honda for technical assistance and thank Prof. K. Ikeda, Prof.K. Maruyama, Prof. Z. J. Wang, Prof. J. Koike, Dr. M. Suzuki, Prof. H. Sato and Dr. T. Tsukeda for their helpful discussions. Financial support from the Japan Ministry of Education, Culture, Sports, Science and Technology for the Promotion of Science with a Grant-in-Aid for Young Researchers and for 21st century COE program in International Center of Research and Education for Materials at Tohoku University is gratefully acknowledged.

PY - 2003/11/1

Y1 - 2003/11/1

N2 - Microstructural evolution of a thixomolded magnesium (Mg) alloy AZ91D during friction stir welding was investigated. Friction stir welding resulted in a homogeneous microstructure consisting of fine recrystallised α-Mg grains in the thixomolded material. The microstructural homogenisation and refinement was attributed to dynamic recrystallisation accompanied by the dissolution of the eutectic structure during the welding. The grain refinement in the stir zone was effective in increasing the hardness, as predicted by the Hall-Petch equation. The effect of grain size on hardness was smaller than that in conventional and rapidly solidified AZ91. This phenomenon may be explained as being due to the microstructure of the stir zone which consisted of fine equiaxed grains with a high density of dislocations.

AB - Microstructural evolution of a thixomolded magnesium (Mg) alloy AZ91D during friction stir welding was investigated. Friction stir welding resulted in a homogeneous microstructure consisting of fine recrystallised α-Mg grains in the thixomolded material. The microstructural homogenisation and refinement was attributed to dynamic recrystallisation accompanied by the dissolution of the eutectic structure during the welding. The grain refinement in the stir zone was effective in increasing the hardness, as predicted by the Hall-Petch equation. The effect of grain size on hardness was smaller than that in conventional and rapidly solidified AZ91. This phenomenon may be explained as being due to the microstructure of the stir zone which consisted of fine equiaxed grains with a high density of dislocations.

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Microstructural evolution and its effect on Hall-Petch relationship in friction stir welding of thixomolded Mg alloy AZ91D

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