Creep damage evaluation of 18Cr–9Ni–3Cu–Nb–N steel by electron backscattered diffraction (EBSD) – comparison of traditional Hough Indexing and novel Spherical Indexing –

The creep damage evaluation of 18Cr-9Ni-3Cu-Nb-N steel creep interrupted and ruptured at 873 K was performed. Kernel average misorientation (KAM) and grain orientation spread (GOS) values obtained by electron backscattered diffraction (EBSD) through two types of indexing procedures, traditional Hough Indexing (HI) and novel Spherical Indexing (SI), were used as the descriptors of creep damage. The SI resulted in a lower KAM value than that obtained via HI, suggesting improved angular resolution and higher sensitivity for creep damage detection at lower strain levels. The GOS of the virgin sample obtained via SI was also lower than that obtained via HI, whereas that of the crept specimens evaluated via SI and HI were almost identical. Nevertheless, by considering the deviation from the initial value, SI also improved the sensitivity of creep damage detection at the lower strain level using GOS. Therefore, this study revealed the effectiveness of creep damage evaluation with SI compared to that with HI.