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jwri37_01_019
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論文情報
タイトル
Effect of Oxygen Content in He-O₂ Shielding Gas on Weld Shape in Ultra Deep Penetration TIG
著者
Fujii, Hidetoshi
Fujii, Hidetoshi
Lu, Shanping
Lu, Shanping
Sato, Toyoyuki
Sato, Toyoyuki
Nogi, Kiyoshi
Nogi, Kiyoshi
キーワード等
Weld shape
Oxygen
Helium
Marangoni convection
Electromagnetic convection
Double shielding gas
Welding current
Welding speed
Tensile strength
Charpy impact test
Bending test
抄録
A new type of TIG welding has been developed, in which an ultra-deep penetration (10mm for one pass) is obtained. In order to control the Marangoni convection induced by the surface tension gradient on the molten pool, He gas containing a small amount of oxidizing gas was used. The effect of the concentration of O₂ and CO₂ in the shielding gas on the weld shape was studied for the bead-on-plate TIG welding of SUS304 stainless under He-O₂ and He-CO₂ mixed shielding gases. Because oxygen is a surface active element for stainless steel, the addition of oxygen to the molten pool can control the Marangoni convection from the outward to inward direction on the liquid pool surface. When the oxygen content in the liquid pool is over a critical value, around 70ppm, the weld shape suddenly changes from a wide shallow shape to a deep narrow shape due to the change in the direction of the Marangoni convection. Also, for He based shielding gas, a high welding current will strengthen both the inward Marangoni convection on the pool surface and the inward electromagnetic convection in the liquid pool. Accordingly, at a welding speed of 0.75mm/s, the welding current of 160A and the electrode gap of 1mm under the He-0.4%O₂ shielding, the depth/width ratio reaches 1.8, which is much larger than for Ar-O₂ shielding gas (0.7) and Ar shielding gas (0.2). The effects of the welding parameters, such as welding speed and welding current, were also systematically investigated. In addition, a double shielding gas method has been developed to prevent any consumption of the tungsten electrode. along the heating line, the inherent deformation of smaller plates, with the same thickness and formed under the same heating and cooling conditions, can be accurately and easily predicted.
公開者
大阪大学接合科学研究所
公開者の別表記
Joining and Welding Research Institute, Osaka University
公開者 (ヨミ)
オオサカ ダイガク セツゴウ カガク ケンキュウジョ
掲載誌名
Transactions of JWRI
巻
37
号
1
開始ページ
19
終了ページ
26
刊行年月
2008-07
ISSN
03874508
NCID
AA00867058
URL
http://hdl.handle.net/11094/6051
言語
英語
カテゴリ
紀要論文 Departmental Bulletin Paper
Transactions of JWRI / Vol.37 No.1 (2008-07)
論文詳細を表示
著者版フラグ
publisher
NII資源タイプ
紀要論文
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紀要論文
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text
DCTERMS.bibliographicCitation
Transactions of JWRI.37(1) P.19-P.26
DC.title
Effect of Oxygen Content in He-O₂ Shielding Gas on Weld Shape in Ultra Deep Penetration TIG
DC.creator
Fujii, Hidetoshi
Lu, Shanping
Sato, Toyoyuki
Nogi, Kiyoshi
DC.publisher
大阪大学接合科学研究所
DC.language" scheme="DCTERMS.RFC1766
英語
DCTERMS.issued" scheme="DCTERMS.W3CDTF
2008-07
DC.identifier" scheme="DCTERMS.URI
http://hdl.handle.net/11094/6051
DC.subject
Weld shape
Oxygen
Helium
Marangoni convection
Electromagnetic convection
Double shielding gas
Welding current
Welding speed
Tensile strength
Charpy impact test
Bending test
DCTERMS.abstract
A new type of TIG welding has been developed, in which an ultra-deep penetration (10mm for one pass) is obtained. In order to control the Marangoni convection induced by the surface tension gradient on the molten pool, He gas containing a small amount of oxidizing gas was used. The effect of the concentration of O₂ and CO₂ in the shielding gas on the weld shape was studied for the bead-on-plate TIG welding of SUS304 stainless under He-O₂ and He-CO₂ mixed shielding gases. Because oxygen is a surface active element for stainless steel, the addition of oxygen to the molten pool can control the Marangoni convection from the outward to inward direction on the liquid pool surface. When the oxygen content in the liquid pool is over a critical value, around 70ppm, the weld shape suddenly changes from a wide shallow shape to a deep narrow shape due to the change in the direction of the Marangoni convection. Also, for He based shielding gas, a high welding current will strengthen both the inward Marangoni convection on the pool surface and the inward electromagnetic convection in the liquid pool. Accordingly, at a welding speed of 0.75mm/s, the welding current of 160A and the electrode gap of 1mm under the He-0.4%O₂ shielding, the depth/width ratio reaches 1.8, which is much larger than for Ar-O₂ shielding gas (0.7) and Ar shielding gas (0.2). The effects of the welding parameters, such as welding speed and welding current, were also systematically investigated. In addition, a double shielding gas method has been developed to prevent any consumption of the tungsten electrode. along the heating line, the inherent deformation of smaller plates, with the same thickness and formed under the same heating and cooling conditions, can be accurately and easily predicted.
citation_title
Effect of Oxygen Content in He-O₂ Shielding Gas on Weld Shape in Ultra Deep Penetration TIG
citation_author
Fujii, Hidetoshi
Lu, Shanping
Sato, Toyoyuki
Nogi, Kiyoshi
citation_publisher
大阪大学接合科学研究所
citation_language
英語
citation_date
2008-07
citation_journal_title
Transactions of JWRI
citation_volume
37
citation_issue
1
citation_firstpage
19
citation_lastpage
26
citation_issn
03874508
citation_public_url
http://hdl.handle.net/11094/6051
citation_keywords
Weld shape
Oxygen
Helium
Marangoni convection
Electromagnetic convection
Double shielding gas
Welding current
Welding speed
Tensile strength
Charpy impact test
Bending test