Title:
WELDING TECHNIQUE FOR FORMING PASSIVE CHROMIUM OXIDE FILM IN WELD AND GAS FEED SYSTEM FOR WELDING
Document Type and Number:
WIPO Patent Application WO/1999/034027
Kind Code:
A1
Abstract:
A welding technique whereby the passivation of chromiun oxide is conducted simultaneously with welding to realize treatment in a short time and in its turn to improve the productivity. Specifically, a technique for welding a weld material, for example, a pipe of a ferritic stainless steel, which comprises: switching a back shielding gas at the time of ordinary welding from an argon gas (or a hydrogen gas/an argon gas) to an argon gas containing an oxidizing gas added at the time of formation of a passive chromium oxide film; presetting the welding temperature conditions at the time of formation of the passive chromium oxide film so as not to cause the inner surface of the pipe to be melted; and, in order to conduct soaking of the pipe welded between the welding condition for the ordinary welding and the welding condition for the formation of a passive chromium oxide film and to replace the gas at the time of the ordinary welding with the gas used at the time of the formation of a passive chromium oxide film, conducting rotation by at least one turn under the welding condition for the formation of a passive chromium oxide film, thus forming a passive chromium oxide film in a weld simultaneously with the welding.
Inventors:
OHMI TADAHIRO (JP)
NITTA TAKAHISA (JP)
SHIRAI YASUYUKI (JP)
NAKAMURA OSAMU (JP)
NITTA TAKAHISA (JP)
SHIRAI YASUYUKI (JP)
NAKAMURA OSAMU (JP)
Application Number:
PCT/JP1998/004493
Publication Date:
July 08, 1999
Filing Date:
October 05, 1998
Export Citation:
Assignee:
OHMI TADAHIRO (JP)
NITTA TAKAHISA (JP)
SHIRAI YASUYUKI (JP)
NAKAMURA OSAMU (JP)
NITTA TAKAHISA (JP)
SHIRAI YASUYUKI (JP)
NAKAMURA OSAMU (JP)
International Classes:
B23K9/00; B23K9/035; B23K9/16; B23K15/10; B23K31/00; B23K35/38; B23K9/04; C23C8/10; C23C8/14; C23C8/18; (IPC1-7): C23C8/12; C23C8/16; B23K31/00; B23K9/16; B23K37/00
Foreign References:
| JPH0978221A | 1997-03-25 | |||
| JPH0518423A | 1993-01-26 | |||
| JPH09195031A | 1997-07-29 |
Attorney, Agent or Firm:
Fukumori, Hisao (2F 5-11, Kudanminami 4-chome Chiyoda-ku Tokyo, JP)
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