V添加10Crフェライト鋼におけるラス境界析出物の3D電子線トモグラフィー観察

Electron tomographic observation of precipitates on lath boundaries in 10Cr ferritic steel bearing V

光原 昌寿*; 池田 賢一*; 波多 聰*; 中島 英治*; 若井 隆純 

Mitsuhara, Masatoshi*; Ikeda, Kenichi*; Hata, Satoshi*; Nakashima, Hideharu*; Wakai, Takashi

Vを添加した10Crフェライト系耐熱鋼において、ラス組織安定化に有効なラス境界上析出物に注目し、その元素分析と3次元形態観察を行った。その結果、塊状とフィルム状の2種類の異なる組成の析出物がラス境界に生成しているが、後者の方が被覆率が高いことがわかった。このような高被覆性析出物は、クリープ変形中のラス組織の回復抑制に有効であり、V添加によるクリープ強度向上の主要因と推察される。

High Cr ferritic steels bearing V have high creep strength due to the precipitation hardening. In order to enhance the efficiency of the precipitation hardening, the elemental components, shape and distribution of the precipitates should be comprehended. In this study, we investigated that of the precipitates in the 10Cr ferritic steel bearing V using the STEM-EDS analysis and the three-dimensional electron tomography (3D-ET) observation. The two types of precipitates on the lath boundaries could be observed, which were lump-shaped precipitates and film-shaped precipitates. They had the different elemental component. From the 3D-ET observation, it revealed that the film-shaped precipitates covered the lath boundary widely. Therefore, the film-shaped precipitates are expected to be effective for the stabilization of martensitic microstructure during the creep deformation.