報告書番号

285048

タイトル（和文）

単結晶超合金の耐食性およびクリープ疲労強度特性の評価

タイトル（英文）

ESTIMATION OF CRROSION RESISTANCE AND CREEP-FATIGUE STRENGTH IN SINGLE CRYSTAL SUPERALLOY

概要 （図表や脚注は「報告書全文」に掲載しております）

埋蔵量の豊富な石炭の有効利用にために石炭ガス化複合発電プラントの開発が進められている。この開発では，プラントのり高効率化が不可欠であるが，高効率化はガスタービンの高温化に依存するため，動静翼等の高温機器要素用の超合金の高強度化が必要とされている。このような状況の下で，一方向凝固や単結晶のような新しい超合金に注目が払われている。特に，単結晶超合金は，前報で述べたように，ガスタービンの高温化に寄与するものと期待されている。本報告では，単結晶超合金ＣＭＳＸ－２の耐食性および高温強度特性について評価を加えた。その結果，本単結晶超合金の耐食性は環境条件に大きく左右され，溶融塩腐食に対しては比較的良好であることがわかった。また，本単結晶超合金のに引張・クリープ破弾特性は結晶方位に強く依存し，その依存性は温度・時間パラメータとともに変化した。さらに，高温疲労寿命に及ぼす環境うこかも明らかになった。

概要 （英文）

A COAL-GASIFICATION COMBINED-CYCLE PLANT IS BEING DEVELOPED FOR THE EFFECTIVE UTILIZATION OF RICH COALS. FOR THE DEVELOPMENT, IT IS ESSENTIAL TO INCREASE THE EFFICIENCY OF THE PLANT. SINCE AN INCREASE IN THE EFFICIENCY DEPENDS ON AN INCREASE IN GAS TURBINE TEMPERATURE, IT IS NECESSARY TO STRENGTHEN SUPERALLOYS FOR HIGH-TEMPERATURE COMPONENTS SUCH AS BALDE AND VANE. UNDER SUCH CONDITIONS, NEW SUPERALLOY SUCH AS DIRECTIONALLY SOLIDIFIED AND SINGLE CRYSTAL SUPERALLOYS ARE BEING GIVEN ATTENTION. IN PARTICULAR, A SINGLE CRYSTAL SUPERALLOY IS EXPECTED TO CONTRIBUTE TO INCREASING THE GAS TURBINE TEMPERATURE AS PRESENTED IN THE PREVOUS REPORT. IN THIS REPORT, THE CORROSION RESISTANCE AND HIGH-TEMPERATURE MECHANICAL PROPERTIES OF A SINGLE CRYSTAL SUPERALLOY, CMSX-2, WERE ESTIMATED. AS A RESULT, COMPARING WITH CONVENTIONALLY CAST AND DIRECTIONALLY SOLIDIFIED SUPERALLOYS (MAR-M247), THE SINGLE CRYSTAL SUPERALLOY WAS FOUND TO HAVE THE LOWEST RESISTANCE TO VANADIUM ATTACK, WHILE THE SUPERALLOY SHOWED BETTER RESISTANCE TO MELTED-SALT CORROSION. IT WAS ALSO FOUND THAT OXIDE SCALE PEELED OFF EASILY IN THE SINGLE CRYSTAL SUPER ALLOY UNDER STATIC AND CYCLIC OXIDATION CONDITIONS. THE TENSILE AND CREEP-RUPTURE PROPERTIES OF CMSX-2 WERE STRONGLY DEPENDENT ON CRYSTALLOGRAPHIC ORIENTATION, AND THE DEPENDENCY CHANGED WITH THE TIME-TEMPERATURE-PARAMETER. FURTHERMORE,ENVIRONMENTAL EFFECTS ON THE HIGH-TEMPERATURE FATIGUE LIFE OF CMSX-2 WERE OBSERVED. AT THE SAME STRAIN CONDITION, THE FATIGUE LIFE AT 900 DEGREE C IN VACUUM WAS TWICE OR MORE AS LONG AS THAT IN AIR, WHILE THE LIFE IN AIR WAS TEN TIMES OR MOREAS LONG AS THAT IN AIR WHILE THE LIFE IN AIR WAS TEN TIMES OR MORE AS LONG AS THAT IN MELTED-SALT CORROSION ENVIRONMENT.

報告者

キーワード