報告書番号

T97033

タイトル（和文）

中性子照射されたステンレス鋼のＩＡＳＣＣ感受性に及ぼす照射後焼鈍の影響

タイトル（英文）

POST-IRRADIATION ANNEALING EFFECT ON IASCC SUSCEPTIBILITY OF NEUTRON IRRADIATED STAINLESS STEELS

概要 （図表や脚注は「報告書全文」に掲載しております）

軽水路温度で最大２．６ｘ１０２５ｎ／ｍ２まで照射された３１６冷間加工材（３１６ＣＷ）と１．０ｘ１０２５ｎ／ｍ２まで照射された３４７溶体化材（３４７ＳＡ）を用いて，６２３～７７３Ｋの間で等時焼鈍を行い，溶存酸素濃度８ｐｐｍの高温高圧水中とＡｒガス中でＳＳＲＴ試験を実施し，照射後焼鈍のＩＡＳＣＣ感受性に及ぼす効果を検討した。主な結果は以下の通り（１）３１６ＣＷのＩＡＳＣＣ感受性は６７３Ｋ焼鈍では未焼鈍材より増加し，７２３Ｋ以上の焼鈍では消失した。（２）３１６ＣＷのＩＡＳＣＣ感受性の増加する温度では焼鈍硬化が生じた。ＩＡＳＣＣ感受性は０．２％耐力が６００ＭＰａ以上で発生しはじめ，耐力の上昇とともに増加した。このことは照射欠陥と不純物の相互作用による硬化がＩＡＳＣＣ感受性に寄与している可能性を示している。

概要 （英文）

POST-IRRADIATION ANNEALING EFFECTS ON IRRADIATED ASSISTED STRESS CORROSION CRACKING (IASCC) WERE STUDIED FOR COLD-WORKED TYPE 316 (316CW) AND SOLUTION-ANNEALED TYPE 347 (347SA) STAINLESSSTEELS IRRADIATED AT 563 K TO MAXIMUM FLUENCES OF 2.6X1025 N/M2 AND 1.0X1025 N/M2, RESPECTIVELY. THE IASCC SUSCEPTIBILITY WAS EXAMINED BY SLOW STRAIN TENSILE TEST (SSRT) IN HIGH-TEMPERATURE (563 K) PRESSURIZED WATER WITH 8 PPM DISSOLVED OXYGEN. TEMPERATURES OF POST-IRRADIATION ANNEALING RANGED FROM 623 K TO 773 K, AND THE ANNEALING TIME WAS 1 HR. TENSILE TESTS WERE ALSO PERFORMED IN AR GAS AT 563 K AT THE SAME STRAIN RATEAS IN THE SSRT TEST. THE MAIN RESULTS WERE AS FOLLOWS: (1) THE IASCC SUSCEPTIBILITY INCREASED FOR 316CW POST-IRRADIATION ANNEALED AT 673 K, BUT DISAPPEARED AFTER ANNEALING AT 773 K, WHILE THE SUSCEPTIBILITY OF 347SA TO IASCC WAS UNCHANGED AFTER ANNEALING AT 673 K. (2) THE TEMPERATURE AT WHICH RADIATION ANNEAL HARDENING WAS OBSERVED COINCIDED WITH THE TEMPERATURE AT WHICH IASCC INCREASED. THE CHANGE IN IASCC SUSCEPTIBILITYDUE TO POST-IRRADIATION ANNEALING WAS CLOSELY RELATED TO RADIATION ANNEAL HARDENING. THUS RADIATION-INDUCED IMPURITY ELEMENT SEGREGATION COMBINED WITH RADIATION DEFECTS MAY HAVE PLAYED A PREDOMINANT ROLE IN IASCCSUSCEPTIBILITY CHANGE IN THIS STUDY.

報告者

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