The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 09, 1997
Filed:
Jun. 20, 1995
Tetsuya Nagata, Hitachi, JP;
Yasuhisa Aono, Hitachi, JP;
Jun'ya Kaneda, Hitachi, JP;
Takahiko Kato, Hitachinaka, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
In a case of welding a highly neutron-irradiated austenitic stainless steel, the portion to be welded is heated under a condition of temperature and time in a predetermined range before welding. In this moment, chromium carbide (Cr.sub.23 C.sub.6) precipitates in the grain boundaries of the stainless steel. Welding is performed the state described above is obtained. Since, chromium carbide has been precipitated in the grain boundary by the heat treatment before welding, any helium atoms generated through nucleus conversion of Ni, are apt to be trapped with the chromium carbide, thereby reducing the number of gas bubbles formed by gathering the helium atoms in the grain boundaries. As a result, since decrease in the strength of the grain boundaries due to helium gas bubbles is moderated, it is possible to prevent occurrence of cracks during welding.