ニッケル基600合金用被覆アーク溶接金属の高温高圧純水中の応力腐食割れ感受性に及ぼすCr濃度の影響
Effect of Chromium Content on Stress Corrosion Cracking of Shielded Metal Arc Weld Metalfor 600 Type Alloy in High Temperature Pressurized Pure Water
著者:
西川 聡 Satoru NISHIKAWA 大北 茂 Shigeru OKITA 山口 篤憲 Atsunori YAMAGUCHI 池内 建二 Kenji IKEUCHI
発刊日:
公開日:
Alloy 600 weld metalCr contentG phasePhosphorusSR+LTAStress corrosion cracking
概要
When their Cr contents were increased to the same level as those of the alloy 82(18-22mass%Cr), the weld metals of alloy 182(13-17mass%Cr) sustained only slight SCCs in the as-welded state, and no crack was detected after the post weld h eat treatment (SR+LTA) of stress relief annealing at 893 K followed by aging at 673 K. These results suggest that the higher Cr content of the alloy 82 is responsible for its higher resistance to SCC than that of the alloy 182. The carbi de, Nijo(Mn, Cr).Siz (G phase) was precipitated at the grain boundary in the alloy 182 containing 18.5mass% Cr when the SR+LTA treatment was applied. TEM-EDS analyses suggested that the G phase was enriched in P, and so could decrease th e P content in the grain boundary region. Probably, the decreased P content at the grain boundary due to the precipitation of G phase contributed to the enhancement of the SCC resistance of the Cr-added alloy 182 by the SR+LTA treatment.
