報告書番号

280044

タイトル（和文）

原子炉冷却系配管用３１６系ステンレス鍛鋼の高温純水中におけるＳＣＣ感受性の評価

タイトル（英文）

EVALUATION OF SCC SUSCEPTIBILITY IN HIGH TEMPERATURE WATER FOR TYPE 316 STAINLESS STEELS COOLING SYSTEM PIPES PRODUCED BY FORGING

概要 （図表や脚注は「報告書全文」に掲載しております）

窒素添加の３種の３１６系ステンレス鍛鋼ハイプに関してＳＣＣ感受性および基礎的諸性質を調べた。（１）０．０１２％Ｃ─０．１３０％Ｎおよび０．０１８Ｃ－０．１３３％Ｎの２種類の３１６ＬＮ鍛鋼の鋭敏化材は良好な粒界腐食性を有する。しかし高炭素（０．０４８％─０．１３９％Ｎ）の３１６Ｎ鍛鋼は鋭敏化されると著しく大きい粒界アタックが認められた。室温および３００Ｃの降伏強度伸び，および絞りの値はいずれも原子力用３１６ステンレス鋼の規格値を十分に満足した。（２）８ｐｐｍ溶存酸素を含む２８８Ｃの高温純水中ＳＣＣ感受性は次のようになる。２種の３１６ＬＮ鍛鋼の鋭敏化材は，最小４．２Ｅ─７／秒の定速引張法，降伏強度の２．２５倍の上限保持応力の激しい交番引張法および定負荷法のいずれのＳＣＣ試験でもＳＣＣ感受性は示さなかった。しかし高炭素の３１６Ｎ鍛

概要 （英文）

FOR THREE KINDS OF NITROGEN-CHARGED 316 STAINLESS STEELS PIPES PRODUCED BY FORGING,THE STRESS CORROSION CRACKING SUSCEPETIBILITY AND FUNDAMENTAL PROPERTIES WERE INVESTIGATED. (1)FUNDAMENTAL PROPERTIES OF THE MATERIALS WERE MAINLY AS FOLLOWS.TWO KINDS OF 316LN FORGED STAINLESS STEELS,WHOSE CARBON AND NITROGEN CONTENTS WERE 0.012%C-0.130%N AND 0.018%C-0.133%N,SHOWED EXTREMELY HIGH RESISTANCE AGAINST INTERGRANULAR CORROSION,ALTHOUGH THEY WERE SEVERELY SENSITIZED BY BOTH FURNACE-HEATING AND WELD-HEATING.HOWEVER,A RELATIVELY HIGH CARBON CHARGED 316N STAINLESS STEEL,WHOSE CARBON AND NITROGEN CONTENTS WERE 0.048%C AND 0.139%N,SHOWED VERY LARGE INTERGRANULAR ATTACK WHEN THE MATERIALWAS HEATED IN SENSITIZING TEMPERATURE. ALL THE TENSILE TEST PROPERTIESOF ABOVE MATERIALS AT ROOM TEMPERATURE AND 300 DEGREE(C),WHICH INCLUDED 0.2% OFFSET PROOF STRESS,ULTIMATE TENSILE STRENGH,TOTAL ELONGATION AND REDUCTION OF AREA,STASFIED THE CRITERIA OF THE NUCLEAR-GRADE 316 STAINLESS STEEL. (2)AS FOLLOWS WAS THE SCC SUSCEPTIBILITY IN 288 DEGREE(C) HIGH PURITY WATER CONTAINING AIR-SATURATED DISSOLVED OXYGEN(APPROXIMATELY 8 PPM).SEVERELY SENSITIZED 316LN STAINLESS STEELS EXHIBITED NO SCC SUSCEPTIBILITY IN ALL SCC TESTS WHICH WERE CONSTANT EXTENSION RATE TEST AT MINIMUM 4.2E-7/S TRAIN RATE,CYCLIC TENSION TEST IN THE TRAPEZOIDAL STRESS WAVEFORM OF 2.25 TIMES YIELD STRESS AS UPPER HOLDING STRESS,AND CONSTANT LOAD TEST AT 2.25 TIMES YIELD STRESS.HOWEVER A SENSITIZED 316N STINLESS STEEL CONTAINING 0.048% CARBON WAS FAILED BY INTERGRANULAR STRESS CORROSION CRACKINGS.

報告者

キーワード