Effect of Oxygen Content in He-O₂ Shielding Gas on Weld Shape in Ultra Deep Penetration TIG

Fujii, Hidetoshi; Lu, Shanping; Sato, Toyoyuki et al.

Transactions of JWRI, 2008, 37(1), 19-26

Number of Access:564（2025-08-14 14:29 Counts）

Identifier to cite or link to this item: https://doi.org/10.18910/6051

Link to primary information 

File Format Terms of use Size Views Date.Available Description information
jwri37_01_019 pdf None 478 KB 547 2012.09.22  

Item Information

Output File Export EndNote Basic Export Mendeley

Title
Effect of Oxygen Content in He-O₂ Shielding Gas on Weld Shape in Ultra Deep Penetration TIG
Creator
NRID
1000000247230 1000000247230
ORCID
0000-0002-5023-3844 0000-0002-5023-3844
researchmap permalink
read0051741 read0051741
Scopus Author ID
7403071460 7403071460
CreatorName
Fujii, Hidetoshi
CreatorName
Lu, Shanping
CreatorName
Sato, Toyoyuki
NRID
1000040029335 1000040029335
CreatorName
Nogi, Kiyoshi
Subject
Weld shape
Oxygen
Helium
Marangoni convection
Electromagnetic convection
Double shielding gas
Welding current
Welding speed
Tensile strength
Charpy impact test
Bending test
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.
Publisher
大阪大学接合科学研究所
オオサカ ダイガク セツゴウ カガク ケンキュウジョ
Joining and Welding Research Institute, Osaka University
Source Title
Transactions of JWRI
Volume (Issue)
37(1)
Page
19-26
Date of Issued
2008-07
Language
English
Handle URL
https://hdl.handle.net/11094/6051
DOI
https://doi.org/10.18910/6051
PISSN
03874508
NCID
AA00867058
Access Rights
open access
oaire:version
Version of Record
Category
紀要論文 Departmental Bulletin Paper
Transactions of JWRI / Vol.37 No.1 (2008-07)