報告書番号

E282014

タイトル（和文）

THE BEHAVIOR OF CRACK PROPAGATION IN INCONEL718 UNDER TRANSITION FROM SMALL SCALE TO LARGE SCALE CREEP

タイトル（英文）

THE BEHAVIOR OF CRACK PROPAGATION IN INCONEL718 UNDER TRANSITION FROM SMALL SCALE TO LARGE SCALE CREEP

概要 （図表や脚注は「報告書全文」に掲載しております）

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概要 （英文）

THIS REPORT PRESENTS THE RESULTS OF ELEVATED-TEMPERATURE LOW-CYCLE FATIGUE CRACK PROPAGATION TESTS IN A GAS TURBINEDISK MATERIAL,INCONEL 718. IT WAS FOUND THAT THE CHARACTERISTICS OF CRACK PROPAGATION WERE CLASSIFIED INTO P-TYPE AND C-TYPE FAYIGUE. IN THE P-TYPE FAIGUE,STRIATIONS WERE OBSERVED ON THE FRACTURE SURFACES AND THECRACK PROPAGATION RATE,DL/DN,WAS CORRELATED WELL WITH THE FATIGUE J-INTEGRAL. ON THE OTHER HAND,IN THE C-TYPE FATIGUE,GRAIN-BOUNDARY FACETS WERE OBESRVED ON THE FRACTURE SURFACES. HOWEVER,THE CRACK PROPAGATION RATE,DL/DT,WAS CORRELATED WELL WITH NEITHER THE MAXIMUM STRESS INTENSITY FACTOR,KMAX,NOR THE STEADY STATE CREEP J-INTEGRAL,JS*. THIS WAS CAUSED BY THE TRANSITION FROM SMALL SACLE CREEP(SSC)TO LARGE SCALE CREEP(LSC)CONDITIONS. SO,A NEW PARAMETER CALLED TIME-AVERAGED CREEP J-INTEGRAL,JT*, WAS PROPOSED IN THIS STUDY.THE PARAMETER WAS BASED ON THE CREEP J-INTEGRAL UNDER THE TRANSIENT CONDITION AND DEMONSTRATED THE GOOD RESULT OFTHE CORRELATION OF DL/DT.

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