報告書番号

283028

タイトル（和文）

ガスタービンディスク用鉄基鍛造超合金Ａ２８６の高温疲労強度特性

タイトル（英文）

THE CHARACTERISITICS OF HIGH-TEMPERATURE FATIGUE STRENGTH IN FE-BASE FORGED SUPERALLOY A286 USED FOR GAS TURBINE DISK

概要 （図表や脚注は「報告書全文」に掲載しております）

鉄基鍛造超合金Ａ－２８６は，ガスタービンディスク，空気圧縮機ディスク等に使用される高温強度に優れた超合金の一つである。当所では，さきにＮｉ基鍛造超合金ＩＮ－７１８の高温疲労強度特性を検討したが，本報告は高温ガスタービンの開発において同合金とともに鍛造合金として重要な本超合金の高温疲労強度特性について検討を加えたものである。Ａ２８６の高温疲労寿命は，引張負荷中のクリープ歪により粒界破壊を呈すると，粒内破壊の場合に比べ低下する。また，本供試材の場合，歪範囲分割法は熱疲労寿命推定に必ずしも適用できるとは限らない。Ａ２８６とＩＮ７１８の高温疲労寿命特性を比較すると，寿命が延性に依存する高歪範囲では延性の大きいＡ２８６の方が長寿命を示し，強度依存性が強くなる低歪範囲では強度に優れたＩＮ７１８の方が長寿命となる。

概要 （英文）

FOR DEVELOPMENT OF A GAS-STEAM COMBINED CYCLE POWER PLANT AIMING AT HIGHER EFFICIENCY, SUPERALLOYS USED FOR HIGH-TEMERATURE COMPONENTS ARE REQUIRED TO HAVE THE EXCELLENT PROPERTIES OF STRENGTH. A FE-BASE FORGED SUPERALLOY, A286, IS ONE OF HIGH-STERNGTH SUPERALLOYS USED FOR GAS TURBINE DISK. AIR-COMPRESSOR DISK, ETC. THE MECHANICAL PROPERTIES OF THIS ALLOY HAVE BEEN WIDELY EVALUATED BY USING A LARGE DISK FORGED EXPERIMENTALLY AS A TEST MATERIAL. HOWEVER, THERE ARE FEW DATA ON THE PROPERTY OF HIGH-TEMPERATURE FATIGUE STRENGTH WHICH IS ONE OF THE MAIN CRITERIA FOR DESIGN OF GAS TURBINE. THE PROPERTY OF HIGH-TEMPERATURE FATIGUE STRENGTH HAS BEEN PREVIOUSLY INVESTIGATED ON A NI-BASE FORGED SUPER-ALLOY, IN 718,IN THIS INSTITUTE. THIS REPORT PRESENTS THE PROPERTY OF HIGH-TEMPERATURE FATIGUE STRENGTH OF A286 WHICH IS AN IMPORTANT FORGED ALLOY TOGETHER WITH IN 718 FOR DEVELOPMENT OF HIGH-TEMPERATURE GAS TURBINE. WHEN INTERGRANULAR FRACTURE IS CAUSED BY CREEP STRAIN DURING TENSILE LOADING, THE HIGH-TEMPERATURE FATIGUE LIFE OF A286 IS SHORTER THAN THAT IN CASE OF TRANSGRANULAR FRACTURE. FOR THIS ALLOY, THE STRAIN RANGE PARTITIONING METHOD IS NOT ALWAYS APPLICABLE TO PREDICTION OF THERMAL FATIGUE LIFE. COMPARING THE PROPERTY OF HIGH-TEMPERATURE FATIGUE LIFE OF A286 WITH THAT OF IN 718, AT HIGH STRAIN RANGE WHERE THE LIFE IS DEPENDENT ON THE DUCTILITY, A286 HAS LONGER LIFE BECAUSE OFTHE HIGHER DUCTILITY OF THIS ALLOY. AT LOW STRAIN RANGER WHERE THE DEPENDENCE OF STRENGTH ON LIFE APPERAS STRONGLY, HOWEVER, IN 718 WITH HIGHER STREGTH HAS LONGER LIFE.

報告者

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