報告書番号

H07008

タイトル（和文）

レーザ超音波による回転体の非接触表面探傷と内部温度測定

タイトル（英文）

Surface flaw detection and internal temperature measurement by laser ultrasound

概要 （図表や脚注は「報告書全文」に掲載しております）

レーザ超音波法は金属部品等の欠陥検出，物性測定，温度測定を非接触で行うことが出来る。本研究では超音波探触子や熱電対などの従来の測定手法の適用が困難な回転試験体の表面欠陥検出と温度測定にレーザ超音波法を適用し，均一速度で回転する円盤状試験体の表面を伝播した表面波，および裏面から反射した縦波と横波の波形を測定した。径方向と円周方向に深さ1mmの模擬欠陥を施したSUS316試験体を用いて欠陥検出実験を行った結果，欠陥の有無は表面波の波形と周波数特性から判断でき，試験体が静止状態にある場合と同様の結果が得られた。また，SUS304，9-Cr鋼，Ni超合金の回転試験体裏面から反射した縦波の到達時間の温度依存性を測定し，これを基に試験体の内部平均温度が求められることを示した。適用温度範囲はSUSとNi超合金については室温～900℃，9-Cr鋼については室温～720℃であった。

概要 （英文）

Laser ultrasound is an effective method for noncontact flaw detection, material property measurement, and temperature measurement. In this research, laser ultrasound was applied to surface flaw detection and temperature measurement of rotating specimens, for which conventional techniques such as ultrasonic inspection using transducers and thermocouples cannot be applied. Laser ultrasound measurement of uniformly rotating specimens showed that waveforms of surface waves, longitudinal waves, and transverse waves can be obtained with reasonable reproducibility and accuracy. For surface flaw detection, a SUS316 specimen with artificial slits of depth 1 mm machined in the radial and tangential directions was used. The rotation rate of the specimen was synchronized with the repetition rate (20 Hz) of the lasers for generation and detection of ultrasound. The presence of the slits could be detected from the waveform and frequency spectrum of the surface acoustic waves which propagated along the specimen surface. For temperature measurement, SUS304, 9-Cr, and Ni superalloy specimens were used, and the rotation rate was not synchronized with the laser repetition rate. The average internal temperature of the specimen could be obtained from the temperature dependence of the arrival time of the longitudinal waves reflected from the back wall. The applicable temperature range was up to 900 degrees C for SUS and Ni superalloy, and up to 720 degrees C for 9-Cr.

報告者

キーワード