EBSD技术在X80环焊热影响区组织表征中的应用

Application of EBSD technology on microstructure characterization of X80 grith welding heat affected zone

利用金相显微镜(Optical Microscopy, OM)、扫描电子显微镜(Scanning Electron Microscopy, SEM)和背散射电子衍射(Electron Back-Scattered Diffraction, EBSD)技术对X80焊接热影响区的显微组织中M/A组元的尺寸、分布、形貌和晶体学特征进行了系统的表征和对比分析。结果表明:在X80环焊热影响区的临界粗晶区中,M/A组元呈岛链状的形式分布在原始奥氏体晶界上。岛链状的M/A组元由大角度晶界包围而成,并会在其周围产生应力场。金相显微镜和扫描电子显微镜只能显示出M/A组元在基体中的尺寸、形貌和分布特征。相比之下,采用EBSD的大、小角度晶界图和菊池带斜率图能进一步表征出这种岛链状M/A组元的界面信息和应力场分布。此外,与EBSD的局部取向差分布图和菊池带衬度图相比,菊池带斜率图更适用于对这种在晶界分布的M/A岛链组织进行表征。

The optical microscopy(OM), scanning electron microscopy(SEM) and electron back-scattered diffraction(EBSD) technology were used to systematically characterized and contrastively analyzed the size, distribution, morphology and crystallographic characteristics of the M/A constituent microstructure in the intercritical coarse grain zone of X80 grith heat affected zone. The results showed that the M/A constituent was distributed along the parent austenite grain boundary in the form of island chain in the intercritical coarse grain zone of X80 grith heat affected zone. The island chain M/A constituent was surrounded by the high angle grain boundary, and a stress field generated around it. The OM and SEM could only present the size, distribution and morphology of this M/A constituent in matrix. In contrast, the use of the grain boundary map and band slope map of EBSD could further characterize the interface information and stress field distribution of this island-type M/A constituent. Moreover, compared with the inverse pole figure map and band contrast map of EBSD, the band slope map was more suitable for the characterization of the M/A island chain structure distributed along grain boundaries.