Boride formation induced by pcBN tool wear in friction-stir-welded stainless steels

Seung Hwan C. Park; Yutaka S. Sato; Hiroyuki Kokawa; Kazutaka Okamoto; Satoshi Hirano; Masahisa Inagaki

doi:10.1007/s11661-008-9709-9

Boride formation induced by pcBN tool wear in friction-stir-welded stainless steels

Seung Hwan C. Park, Yutaka S. Sato, Hiroyuki Kokawa, Kazutaka Okamoto, Satoshi Hirano, Masahisa Inagaki

ENG - Materials Processing

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

70 Citations (Scopus)

Abstract

The wear of polycrystalline cubic boron nitride (pcBN) tool and its effect on second phase formation were investigated in stainless steel friction-stir (FS) welds. The nitrogen content and the flow stress were analyzed in these welds to examine pcBN tool wear. The nitrogen content in stir zone (SZ) was found to be higher in the austenitic stainless steel FS welds than in the ferritic and duplex stainless steel welds. The flow stress of austenitic stainless steels was almost 1.5 times larger than that of ferritic and duplex stainless steels. These results suggest that the higher flow stress causes the severe tool wear in austenitic stainless steels, which results in greater nitrogen pickup in austenitic stainless steel FS welds. From the microstructural observation, a possibility was suggested that Cr-rich borides with a crystallographic structure of Cr₂B and Cr₅ B₃ formed through the reaction between the increased boron and nitrogen and the matrix during FS welding (FSW).

Original language	English
Pages (from-to)	625-636
Number of pages	12
Journal	Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume	40
Issue number	3
DOIs	https://doi.org/10.1007/s11661-008-9709-9
Publication status	Published - 2009

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title = "Boride formation induced by pcBN tool wear in friction-stir-welded stainless steels",

abstract = "The wear of polycrystalline cubic boron nitride (pcBN) tool and its effect on second phase formation were investigated in stainless steel friction-stir (FS) welds. The nitrogen content and the flow stress were analyzed in these welds to examine pcBN tool wear. The nitrogen content in stir zone (SZ) was found to be higher in the austenitic stainless steel FS welds than in the ferritic and duplex stainless steel welds. The flow stress of austenitic stainless steels was almost 1.5 times larger than that of ferritic and duplex stainless steels. These results suggest that the higher flow stress causes the severe tool wear in austenitic stainless steels, which results in greater nitrogen pickup in austenitic stainless steel FS welds. From the microstructural observation, a possibility was suggested that Cr-rich borides with a crystallographic structure of Cr2B and Cr5 B3 formed through the reaction between the increased boron and nitrogen and the matrix during FS welding (FSW).",

author = "Park, {Seung Hwan C.} and Sato, {Yutaka S.} and Hiroyuki Kokawa and Kazutaka Okamoto and Satoshi Hirano and Masahisa Inagaki",

note = "Funding Information: The authors sincerely thank Professors K. Ikeda, K. Maruyama, T.W. Nelson, C.D. Sorensen, and Z.J. Wang, for many helpful suggestions and advice, and Mr. A. Honda, Mr. M. Doi, and H. Matsumoto for there technical assistance. 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 the Global COE Program in Materials Integration International Center of Education and Research at Tohoku University is gratefully acknowledged.",

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doi = "10.1007/s11661-008-9709-9",

language = "English",

volume = "40",

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T1 - Boride formation induced by pcBN tool wear in friction-stir-welded stainless steels

AU - Park, Seung Hwan C.

AU - Sato, Yutaka S.

AU - Kokawa, Hiroyuki

AU - Okamoto, Kazutaka

AU - Hirano, Satoshi

AU - Inagaki, Masahisa

N1 - Funding Information: The authors sincerely thank Professors K. Ikeda, K. Maruyama, T.W. Nelson, C.D. Sorensen, and Z.J. Wang, for many helpful suggestions and advice, and Mr. A. Honda, Mr. M. Doi, and H. Matsumoto for there technical assistance. 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 the Global COE Program in Materials Integration International Center of Education and Research at Tohoku University is gratefully acknowledged.

PY - 2009

Y1 - 2009

N2 - The wear of polycrystalline cubic boron nitride (pcBN) tool and its effect on second phase formation were investigated in stainless steel friction-stir (FS) welds. The nitrogen content and the flow stress were analyzed in these welds to examine pcBN tool wear. The nitrogen content in stir zone (SZ) was found to be higher in the austenitic stainless steel FS welds than in the ferritic and duplex stainless steel welds. The flow stress of austenitic stainless steels was almost 1.5 times larger than that of ferritic and duplex stainless steels. These results suggest that the higher flow stress causes the severe tool wear in austenitic stainless steels, which results in greater nitrogen pickup in austenitic stainless steel FS welds. From the microstructural observation, a possibility was suggested that Cr-rich borides with a crystallographic structure of Cr2B and Cr5 B3 formed through the reaction between the increased boron and nitrogen and the matrix during FS welding (FSW).

AB - The wear of polycrystalline cubic boron nitride (pcBN) tool and its effect on second phase formation were investigated in stainless steel friction-stir (FS) welds. The nitrogen content and the flow stress were analyzed in these welds to examine pcBN tool wear. The nitrogen content in stir zone (SZ) was found to be higher in the austenitic stainless steel FS welds than in the ferritic and duplex stainless steel welds. The flow stress of austenitic stainless steels was almost 1.5 times larger than that of ferritic and duplex stainless steels. These results suggest that the higher flow stress causes the severe tool wear in austenitic stainless steels, which results in greater nitrogen pickup in austenitic stainless steel FS welds. From the microstructural observation, a possibility was suggested that Cr-rich borides with a crystallographic structure of Cr2B and Cr5 B3 formed through the reaction between the increased boron and nitrogen and the matrix during FS welding (FSW).

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Boride formation induced by pcBN tool wear in friction-stir-welded stainless steels

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