STP1366: Thick Plate Welding of Irradiated Stainless Steel

    Asano, K
    Materials Engineering Group, Tokyo Electric Power Co. Inc., Yokohama,

    Katsura, R
    Nippon Nuclear Fuel Development Co. Ltd., Ibaraki,

    Kawano, S
    Power & Industrial Systems R&D Center, Toshiba Corporation, Yokohama,

    Koshiishi, M
    Hitachi Limited, Hitachi,

    Pages: 15    Published: Jan 2000


    Abstract

    Recent welding tests using either neutron irradiated or tritium charged material have shown that there was a good chance of success when there was no repeated heat cycle during welding, e.g., stringer bead welding, single pass laser welding, etc. However, the replacement/repair of the actual load carrying components often requires thick plate welding which can only be realized with multi-layer welding. In the present study, 20-mm-thick grooved plate of type 304 stainless steel was irradiated and then butt-welded by multi-layer welding. The weld heat input used was 1.0 and 2.0 MJ/m, which required 28 and 14 passes to fill up the groove. The samples were irradiated to 2.5×1021 ∼ 1.8×1023 n/m2 (E>1MeV), which resulted in 0.1∼1.6 appm of helium being produced. A conventional gas tungsten arc welding procedure was employed. The welded joints were subjected to the tensile test, side bend test, root bend test and cross-sectional metallography. The samples containing as much as 0.14 appm of helium passed all the tests; the mechanical properties fulfilled the standard requirement for the unirradiated base metal. At 0.6 appmHe and 1.0 MJ/m heat input, the welded joint showed sufficient strength, however, tiny intergranular cracking was observed in the HAZ where repetitive thermal cycles operated.

    Keywords:

    irradiated stainless steel, weldability test, multi-layer welding, mechanical properties, welded joint, helium bubbles


    Paper ID: STP12443S

    Committee/Subcommittee: E10.08

    DOI: 10.1520/STP12443S


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